1. 09 9月, 2015 7 次提交
  2. 05 9月, 2015 3 次提交
    • A
      userfaultfd: propagate the full address in THP faults · 230c92a8
      Andrea Arcangeli 提交于
      The THP faults were not propagating the original fault address.  The
      latest version of the API with uffd.arg.pagefault.address is supposed to
      propagate the full address through THP faults.
      
      This was not a kernel crashing bug and it wouldn't risk to corrupt user
      memory, but it would cause a SIGBUS failure because the wrong page was
      being copied.
      
      For various reasons this wasn't easily reproducible in the qemu workload,
      but the strestest exposed the problem immediately.
      Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      230c92a8
    • A
      userfaultfd: prevent khugepaged to merge if userfaultfd is armed · c1294d05
      Andrea Arcangeli 提交于
      If userfaultfd is armed on a certain vma we can't "fill" the holes with
      zeroes or we'll break the userland on demand paging.  The holes if the
      userfault is armed, are really missing information (not zeroes) that the
      userland has to load from network or elsewhere.
      
      The same issue happens for wrprotected ptes that we can't just convert
      into a single writable pmd_trans_huge.
      
      We could however in theory still merge across zeropages if only
      VM_UFFD_MISSING is set (so if VM_UFFD_WP is not set)...  that could be
      slightly improved but it'd be much more complex code for a tiny corner
      case.
      Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
      Acked-by: NPavel Emelyanov <xemul@parallels.com>
      Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com>
      Cc: zhang.zhanghailiang@huawei.com
      Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
      Cc: Andres Lagar-Cavilla <andreslc@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Peter Feiner <pfeiner@google.com>
      Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c1294d05
    • A
      userfaultfd: call handle_userfault() for userfaultfd_missing() faults · 6b251fc9
      Andrea Arcangeli 提交于
      This is where the page faults must be modified to call
      handle_userfault() if userfaultfd_missing() is true (so if the
      vma->vm_flags had VM_UFFD_MISSING set).
      
      handle_userfault() then takes care of blocking the page fault and
      delivering it to userland.
      
      The fault flags must also be passed as parameter so the "read|write"
      kind of fault can be passed to userland.
      Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
      Acked-by: NPavel Emelyanov <xemul@parallels.com>
      Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com>
      Cc: zhang.zhanghailiang@huawei.com
      Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
      Cc: Andres Lagar-Cavilla <andreslc@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Peter Feiner <pfeiner@google.com>
      Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      6b251fc9
  3. 07 8月, 2015 1 次提交
    • N
      mm: check __PG_HWPOISON separately from PAGE_FLAGS_CHECK_AT_* · f4c18e6f
      Naoya Horiguchi 提交于
      The race condition addressed in commit add05cec ("mm: soft-offline:
      don't free target page in successful page migration") was not closed
      completely, because that can happen not only for soft-offline, but also
      for hard-offline.  Consider that a slab page is about to be freed into
      buddy pool, and then an uncorrected memory error hits the page just
      after entering __free_one_page(), then VM_BUG_ON_PAGE(page->flags &
      PAGE_FLAGS_CHECK_AT_PREP) is triggered, despite the fact that it's not
      necessary because the data on the affected page is not consumed.
      
      To solve it, this patch drops __PG_HWPOISON from page flag checks at
      allocation/free time.  I think it's justified because __PG_HWPOISON
      flags is defined to prevent the page from being reused, and setting it
      outside the page's alloc-free cycle is a designed behavior (not a bug.)
      
      For recent months, I was annoyed about BUG_ON when soft-offlined page
      remains on lru cache list for a while, which is avoided by calling
      put_page() instead of putback_lru_page() in page migration's success
      path.  This means that this patch reverts a major change from commit
      add05cec about the new refcounting rule of soft-offlined pages, so
      "reuse window" revives.  This will be closed by a subsequent patch.
      Signed-off-by: NNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: Dean Nelson <dnelson@redhat.com>
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: David Rientjes <rientjes@google.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f4c18e6f
  4. 25 6月, 2015 3 次提交
  5. 16 4月, 2015 5 次提交
  6. 15 4月, 2015 3 次提交
  7. 26 3月, 2015 4 次提交
    • M
      mm: numa: mark huge PTEs young when clearing NUMA hinting faults · b7b04004
      Mel Gorman 提交于
      Base PTEs are marked young when the NUMA hinting information is cleared
      but the same does not happen for huge pages which this patch addresses.
      
      Note that migrated pages are not marked young as the base page migration
      code does not assume that migrated pages have been referenced.  This
      could be addressed but beyond the scope of this series which is aimed at
      Dave Chinners shrink workload that is unlikely to be affected by this
      issue.
      Signed-off-by: NMel Gorman <mgorman@suse.de>
      Cc: Dave Chinner <david@fromorbit.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b7b04004
    • M
      mm: numa: slow PTE scan rate if migration failures occur · 074c2381
      Mel Gorman 提交于
      Dave Chinner reported the following on https://lkml.org/lkml/2015/3/1/226
      
        Across the board the 4.0-rc1 numbers are much slower, and the degradation
        is far worse when using the large memory footprint configs. Perf points
        straight at the cause - this is from 4.0-rc1 on the "-o bhash=101073" config:
      
         -   56.07%    56.07%  [kernel]            [k] default_send_IPI_mask_sequence_phys
            - default_send_IPI_mask_sequence_phys
               - 99.99% physflat_send_IPI_mask
                  - 99.37% native_send_call_func_ipi
                       smp_call_function_many
                     - native_flush_tlb_others
                        - 99.85% flush_tlb_page
                             ptep_clear_flush
                             try_to_unmap_one
                             rmap_walk
                             try_to_unmap
                             migrate_pages
                             migrate_misplaced_page
                           - handle_mm_fault
                              - 99.73% __do_page_fault
                                   trace_do_page_fault
                                   do_async_page_fault
                                 + async_page_fault
                    0.63% native_send_call_func_single_ipi
                       generic_exec_single
                       smp_call_function_single
      
      This is showing excessive migration activity even though excessive
      migrations are meant to get throttled.  Normally, the scan rate is tuned
      on a per-task basis depending on the locality of faults.  However, if
      migrations fail for any reason then the PTE scanner may scan faster if
      the faults continue to be remote.  This means there is higher system CPU
      overhead and fault trapping at exactly the time we know that migrations
      cannot happen.  This patch tracks when migration failures occur and
      slows the PTE scanner.
      Signed-off-by: NMel Gorman <mgorman@suse.de>
      Reported-by: NDave Chinner <david@fromorbit.com>
      Tested-by: NDave Chinner <david@fromorbit.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      074c2381
    • M
      mm: numa: preserve PTE write permissions across a NUMA hinting fault · b191f9b1
      Mel Gorman 提交于
      Protecting a PTE to trap a NUMA hinting fault clears the writable bit
      and further faults are needed after trapping a NUMA hinting fault to set
      the writable bit again.  This patch preserves the writable bit when
      trapping NUMA hinting faults.  The impact is obvious from the number of
      minor faults trapped during the basis balancing benchmark and the system
      CPU usage;
      
        autonumabench
                                                   4.0.0-rc4             4.0.0-rc4
                                                    baseline              preserve
        Time System-NUMA01                  107.13 (  0.00%)      103.13 (  3.73%)
        Time System-NUMA01_THEADLOCAL       131.87 (  0.00%)       83.30 ( 36.83%)
        Time System-NUMA02                    8.95 (  0.00%)       10.72 (-19.78%)
        Time System-NUMA02_SMT                4.57 (  0.00%)        3.99 ( 12.69%)
        Time Elapsed-NUMA01                 515.78 (  0.00%)      517.26 ( -0.29%)
        Time Elapsed-NUMA01_THEADLOCAL      384.10 (  0.00%)      384.31 ( -0.05%)
        Time Elapsed-NUMA02                  48.86 (  0.00%)       48.78 (  0.16%)
        Time Elapsed-NUMA02_SMT              47.98 (  0.00%)       48.12 ( -0.29%)
      
                     4.0.0-rc4   4.0.0-rc4
                      baseline    preserve
        User          44383.95    43971.89
        System          252.61      201.24
        Elapsed         998.68     1000.94
      
        Minor Faults   2597249     1981230
        Major Faults       365         364
      
      There is a similar drop in system CPU usage using Dave Chinner's xfsrepair
      workload
      
                                            4.0.0-rc4             4.0.0-rc4
                                             baseline              preserve
        Amean    real-xfsrepair      454.14 (  0.00%)      442.36 (  2.60%)
        Amean    syst-xfsrepair      277.20 (  0.00%)      204.68 ( 26.16%)
      
      The patch looks hacky but the alternatives looked worse.  The tidest was
      to rewalk the page tables after a hinting fault but it was more complex
      than this approach and the performance was worse.  It's not generally
      safe to just mark the page writable during the fault if it's a write
      fault as it may have been read-only for COW so that approach was
      discarded.
      Signed-off-by: NMel Gorman <mgorman@suse.de>
      Reported-by: NDave Chinner <david@fromorbit.com>
      Tested-by: NDave Chinner <david@fromorbit.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b191f9b1
    • M
      mm: numa: group related processes based on VMA flags instead of page table flags · bea66fbd
      Mel Gorman 提交于
      These are three follow-on patches based on the xfsrepair workload Dave
      Chinner reported was problematic in 4.0-rc1 due to changes in page table
      management -- https://lkml.org/lkml/2015/3/1/226.
      
      Much of the problem was reduced by commit 53da3bc2 ("mm: fix up numa
      read-only thread grouping logic") and commit ba68bc01 ("mm: thp:
      Return the correct value for change_huge_pmd").  It was known that the
      performance in 3.19 was still better even if is far less safe.  This
      series aims to restore the performance without compromising on safety.
      
      For the test of this mail, I'm comparing 3.19 against 4.0-rc4 and the
      three patches applied on top
      
        autonumabench
                                                      3.19.0             4.0.0-rc4             4.0.0-rc4             4.0.0-rc4             4.0.0-rc4
                                                     vanilla               vanilla          vmwrite-v5r8         preserve-v5r8         slowscan-v5r8
        Time System-NUMA01                  124.00 (  0.00%)      161.86 (-30.53%)      107.13 ( 13.60%)      103.13 ( 16.83%)      145.01 (-16.94%)
        Time System-NUMA01_THEADLOCAL       115.54 (  0.00%)      107.64 (  6.84%)      131.87 (-14.13%)       83.30 ( 27.90%)       92.35 ( 20.07%)
        Time System-NUMA02                    9.35 (  0.00%)       10.44 (-11.66%)        8.95 (  4.28%)       10.72 (-14.65%)        8.16 ( 12.73%)
        Time System-NUMA02_SMT                3.87 (  0.00%)        4.63 (-19.64%)        4.57 (-18.09%)        3.99 ( -3.10%)        3.36 ( 13.18%)
        Time Elapsed-NUMA01                 570.06 (  0.00%)      567.82 (  0.39%)      515.78 (  9.52%)      517.26 (  9.26%)      543.80 (  4.61%)
        Time Elapsed-NUMA01_THEADLOCAL      393.69 (  0.00%)      384.83 (  2.25%)      384.10 (  2.44%)      384.31 (  2.38%)      380.73 (  3.29%)
        Time Elapsed-NUMA02                  49.09 (  0.00%)       49.33 ( -0.49%)       48.86 (  0.47%)       48.78 (  0.63%)       50.94 ( -3.77%)
        Time Elapsed-NUMA02_SMT              47.51 (  0.00%)       47.15 (  0.76%)       47.98 ( -0.99%)       48.12 ( -1.28%)       49.56 ( -4.31%)
      
                      3.19.0   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4
                     vanilla     vanillavmwrite-v5r8preserve-v5r8slowscan-v5r8
        User        46334.60    46391.94    44383.95    43971.89    44372.12
        System        252.84      284.66      252.61      201.24      249.00
        Elapsed      1062.14     1050.96      998.68     1000.94     1026.78
      
      Overall the system CPU usage is comparable and the test is naturally a
      bit variable.  The slowing of the scanner hurts numa01 but on this
      machine it is an adverse workload and patches that dramatically help it
      often hurt absolutely everything else.
      
      Due to patch 2, the fault activity is interesting
      
                                        3.19.0   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4
                                       vanilla     vanillavmwrite-v5r8preserve-v5r8slowscan-v5r8
        Minor Faults                   2097811     2656646     2597249     1981230     1636841
        Major Faults                       362         450         365         364         365
      
      Note the impact preserving the write bit across protection updates and
      fault reduces faults.
      
        NUMA alloc hit                 1229008     1217015     1191660     1178322     1199681
        NUMA alloc miss                      0           0           0           0           0
        NUMA interleave hit                  0           0           0           0           0
        NUMA alloc local               1228514     1216317     1190871     1177448     1199021
        NUMA base PTE updates        245706197   240041607   238195516   244704842   115012800
        NUMA huge PMD updates           479530      468448      464868      477573      224487
        NUMA page range updates      491225557   479886983   476207932   489222218   229950144
        NUMA hint faults                659753      656503      641678      656926      294842
        NUMA hint local faults          381604      373963      360478      337585      186249
        NUMA hint local percent             57          56          56          51          63
        NUMA pages migrated            5412140     6374899     6266530     5277468     5755096
        AutoNUMA cost                    5121%       5083%       4994%       5097%       2388%
      
      Here the impact of slowing the PTE scanner on migratrion failures is
      obvious as "NUMA base PTE updates" and "NUMA huge PMD updates" are
      massively reduced even though the headline performance is very similar.
      
      As xfsrepair was the reported workload here is the impact of the series
      on it.
      
        xfsrepair
                                               3.19.0             4.0.0-rc4             4.0.0-rc4             4.0.0-rc4             4.0.0-rc4
                                              vanilla               vanilla          vmwrite-v5r8         preserve-v5r8         slowscan-v5r8
        Min      real-fsmark        1183.29 (  0.00%)     1165.73 (  1.48%)     1152.78 (  2.58%)     1153.64 (  2.51%)     1177.62 (  0.48%)
        Min      syst-fsmark        4107.85 (  0.00%)     4027.75 (  1.95%)     3986.74 (  2.95%)     3979.16 (  3.13%)     4048.76 (  1.44%)
        Min      real-xfsrepair      441.51 (  0.00%)      463.96 ( -5.08%)      449.50 ( -1.81%)      440.08 (  0.32%)      439.87 (  0.37%)
        Min      syst-xfsrepair      195.76 (  0.00%)      278.47 (-42.25%)      262.34 (-34.01%)      203.70 ( -4.06%)      143.64 ( 26.62%)
        Amean    real-fsmark        1188.30 (  0.00%)     1177.34 (  0.92%)     1157.97 (  2.55%)     1158.21 (  2.53%)     1182.22 (  0.51%)
        Amean    syst-fsmark        4111.37 (  0.00%)     4055.70 (  1.35%)     3987.19 (  3.02%)     3998.72 (  2.74%)     4061.69 (  1.21%)
        Amean    real-xfsrepair      450.88 (  0.00%)      468.32 ( -3.87%)      454.14 ( -0.72%)      442.36 (  1.89%)      440.59 (  2.28%)
        Amean    syst-xfsrepair      199.66 (  0.00%)      290.60 (-45.55%)      277.20 (-38.84%)      204.68 ( -2.51%)      150.55 ( 24.60%)
        Stddev   real-fsmark           4.12 (  0.00%)       10.82 (-162.29%)       4.14 ( -0.28%)        5.98 (-45.05%)        4.60 (-11.53%)
        Stddev   syst-fsmark           2.63 (  0.00%)       20.32 (-671.82%)       0.37 ( 85.89%)       16.47 (-525.59%)      15.05 (-471.79%)
        Stddev   real-xfsrepair        6.87 (  0.00%)        4.55 ( 33.75%)        3.46 ( 49.58%)        1.78 ( 74.12%)        0.52 ( 92.50%)
        Stddev   syst-xfsrepair        3.02 (  0.00%)       10.30 (-241.37%)      13.17 (-336.37%)       0.71 ( 76.63%)        5.00 (-65.61%)
        CoeffVar real-fsmark           0.35 (  0.00%)        0.92 (-164.73%)       0.36 ( -2.91%)        0.52 (-48.82%)        0.39 (-12.10%)
        CoeffVar syst-fsmark           0.06 (  0.00%)        0.50 (-682.41%)       0.01 ( 85.45%)        0.41 (-543.22%)       0.37 (-478.78%)
        CoeffVar real-xfsrepair        1.52 (  0.00%)        0.97 ( 36.21%)        0.76 ( 49.94%)        0.40 ( 73.62%)        0.12 ( 92.33%)
        CoeffVar syst-xfsrepair        1.51 (  0.00%)        3.54 (-134.54%)       4.75 (-214.31%)       0.34 ( 77.20%)        3.32 (-119.63%)
        Max      real-fsmark        1193.39 (  0.00%)     1191.77 (  0.14%)     1162.90 (  2.55%)     1166.66 (  2.24%)     1188.50 (  0.41%)
        Max      syst-fsmark        4114.18 (  0.00%)     4075.45 (  0.94%)     3987.65 (  3.08%)     4019.45 (  2.30%)     4082.80 (  0.76%)
        Max      real-xfsrepair      457.80 (  0.00%)      474.60 ( -3.67%)      457.82 ( -0.00%)      444.42 (  2.92%)      441.03 (  3.66%)
        Max      syst-xfsrepair      203.11 (  0.00%)      303.65 (-49.50%)      294.35 (-44.92%)      205.33 ( -1.09%)      155.28 ( 23.55%)
      
      The really relevant lines as syst-xfsrepair which is the system CPU
      usage when running xfsrepair.  Note that on my machine the overhead was
      45% higher on 4.0-rc4 which may be part of what Dave is seeing.  Once we
      preserve the write bit across faults, it's only 2.51% higher on average.
      With the full series applied, system CPU usage is 24.6% lower on
      average.
      
      Again, the impact of preserving the write bit on minor faults is obvious
      and the impact of slowing scanning after migration failures is obvious
      on the PTE updates.  Note also that the number of pages migrated is much
      reduced even though the headline performance is comparable.
      
                                        3.19.0   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4
                                       vanilla     vanillavmwrite-v5r8preserve-v5r8slowscan-v5r8
        Minor Faults                 153466827   254507978   249163829   153501373   105737890
        Major Faults                       610         702         690         649         724
        NUMA base PTE updates        217735049   210756527   217729596   216937111   144344993
        NUMA huge PMD updates           129294       85044      106921      127246       79887
        NUMA pages migrated           21938995    29705270    28594162    22687324    16258075
      
                              3.19.0   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4
                             vanilla     vanillavmwrite-v5r8preserve-v5r8slowscan-v5r8
        Mean sdb-avgqusz       13.47        2.54        2.55        2.47        2.49
        Mean sdb-avgrqsz      202.32      140.22      139.50      139.02      138.12
        Mean sdb-await         25.92        5.09        5.33        5.02        5.22
        Mean sdb-r_await        4.71        0.19        0.83        0.51        0.11
        Mean sdb-w_await      104.13        5.21        5.38        5.05        5.32
        Mean sdb-svctm          0.59        0.13        0.14        0.13        0.14
        Mean sdb-rrqm           0.16        0.00        0.00        0.00        0.00
        Mean sdb-wrqm           3.59     1799.43     1826.84     1812.21     1785.67
        Max  sdb-avgqusz      111.06       12.13       14.05       11.66       15.60
        Max  sdb-avgrqsz      255.60      190.34      190.01      187.33      191.78
        Max  sdb-await        168.24       39.28       49.22       44.64       65.62
        Max  sdb-r_await      660.00       52.00      280.00       76.00       12.00
        Max  sdb-w_await     7804.00       39.28       49.22       44.64       65.62
        Max  sdb-svctm          4.00        2.82        2.86        1.98        2.84
        Max  sdb-rrqm           8.30        0.00        0.00        0.00        0.00
        Max  sdb-wrqm          34.20     5372.80     5278.60     5386.60     5546.15
      
      FWIW, I also checked SPECjbb in different configurations but it's
      similar observations -- minor faults lower, PTE update activity lower
      and performance is roughly comparable against 3.19.
      
      This patch (of 3):
      
      Threads that share writable data within pages are grouped together as
      related tasks.  This decision is based on whether the PTE is marked
      dirty which is subject to timing races between the PTE scanner update
      and when the application writes the page.  If the page is file-backed,
      then background flushes and sync also affect placement.  This is
      unpredictable behaviour which is impossible to reason about so this
      patch makes grouping decisions based on the VMA flags.
      Signed-off-by: NMel Gorman <mgorman@suse.de>
      Reported-by: NDave Chinner <david@fromorbit.com>
      Tested-by: NDave Chinner <david@fromorbit.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      bea66fbd
  8. 13 3月, 2015 1 次提交
  9. 12 3月, 2015 1 次提交
    • L
      mm: fix up numa read-only thread grouping logic · 53da3bc2
      Linus Torvalds 提交于
      Dave Chinner reported that commit 4d942466 ("mm: convert
      p[te|md]_mknonnuma and remaining page table manipulations") slowed down
      his xfsrepair test enormously.  In particular, it was using more system
      time due to extra TLB flushing.
      
      The ultimate reason turns out to be how the change to use the regular
      page table accessor functions broke the NUMA grouping logic.  The old
      special mknuma/mknonnuma code accessed the page table present bit and
      the magic NUMA bit directly, while the new code just changes the page
      protections using PROT_NONE and the regular vma protections.
      
      That sounds equivalent, and from a fault standpoint it really is, but a
      subtle side effect is that the *other* protection bits of the page table
      entries also change.  And the code to decide how to group the NUMA
      entries together used the writable bit to decide whether a particular
      page was likely to be shared read-only or not.
      
      And with the change to make the NUMA handling use the regular permission
      setting functions, that writable bit was basically always cleared for
      private mappings due to COW.  So even if the page actually ends up being
      written to in the end, the NUMA balancing would act as if it was always
      shared RO.
      
      This code is a heuristic anyway, so the fix - at least for now - is to
      instead check whether the page is dirty rather than writable.  The bit
      doesn't change with protection changes.
      
      NOTE! This also adds a FIXME comment to revisit this issue,
      
      Not only should we probably re-visit the whole "is this a shared
      read-only page" heuristic (we might want to take the vma permissions
      into account and base this more on those than the per-page ones, and
      also look at whether the particular access that triggers it is a write
      or not), but the whole COW issue shows that we should think about the
      NUMA fault handling some more.
      
      For example, maybe we should do the early-COW thing that a regular fault
      does.  Or maybe we should accept that while using the same bits as
      PROTNONE was a good thing (and got rid of the specual NUMA bit), we
      might still want to just preseve the other protection bits across NUMA
      faulting.
      
      Those are bigger questions, left for later.  This just fixes up the
      heuristic so that it at least approximates working again.  More analysis
      and work needed.
      Reported-by: NDave Chinner <david@fromorbit.com>
      Tested-by: NMel Gorman <mgorman@suse.de>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
      Cc: Ingo Molnar <mingo@kernel.org>,
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      53da3bc2
  10. 13 2月, 2015 6 次提交
    • M
      mm: numa: avoid unnecessary TLB flushes when setting NUMA hinting entries · 10c1045f
      Mel Gorman 提交于
      If a PTE or PMD is already marked NUMA when scanning to mark entries for
      NUMA hinting then it is not necessary to update the entry and incur a TLB
      flush penalty.  Avoid the avoidhead where possible.
      Signed-off-by: NMel Gorman <mgorman@suse.de>
      Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Dave Jones <davej@redhat.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Sasha Levin <sasha.levin@oracle.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      10c1045f
    • M
      mm: numa: add paranoid check around pte_protnone_numa · c0e7cad9
      Mel Gorman 提交于
      pte_protnone_numa is only safe to use after VMA checks for PROT_NONE are
      complete.  Treating a real PROT_NONE PTE as a NUMA hinting fault is going
      to result in strangeness so add a check for it.  BUG_ON looks like
      overkill but if this is hit then it's a serious bug that could result in
      corruption so do not even try recovering.  It would have been more
      comprehensive to check VMA flags in pte_protnone_numa but it would have
      made the API ugly just for a debugging check.
      Signed-off-by: NMel Gorman <mgorman@suse.de>
      Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Dave Jones <davej@redhat.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Sasha Levin <sasha.levin@oracle.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c0e7cad9
    • M
      mm: numa: do not trap faults on the huge zero page · e944fd67
      Mel Gorman 提交于
      Faults on the huge zero page are pointless and there is a BUG_ON to catch
      them during fault time.  This patch reintroduces a check that avoids
      marking the zero page PAGE_NONE.
      Signed-off-by: NMel Gorman <mgorman@suse.de>
      Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Dave Jones <davej@redhat.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Sasha Levin <sasha.levin@oracle.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      e944fd67
    • M
      mm: convert p[te|md]_mknonnuma and remaining page table manipulations · 4d942466
      Mel Gorman 提交于
      With PROT_NONE, the traditional page table manipulation functions are
      sufficient.
      
      [andre.przywara@arm.com: fix compiler warning in pmdp_invalidate()]
      [akpm@linux-foundation.org: fix build with STRICT_MM_TYPECHECKS]
      Signed-off-by: NMel Gorman <mgorman@suse.de>
      Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
      Acked-by: NAneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
      Tested-by: NSasha Levin <sasha.levin@oracle.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Dave Jones <davej@redhat.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Rik van Riel <riel@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4d942466
    • M
      mm: convert p[te|md]_numa users to p[te|md]_protnone_numa · 8a0516ed
      Mel Gorman 提交于
      Convert existing users of pte_numa and friends to the new helper.  Note
      that the kernel is broken after this patch is applied until the other page
      table modifiers are also altered.  This patch layout is to make review
      easier.
      Signed-off-by: NMel Gorman <mgorman@suse.de>
      Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
      Acked-by: NAneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
      Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
      Tested-by: NSasha Levin <sasha.levin@oracle.com>
      Cc: Dave Jones <davej@redhat.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Sasha Levin <sasha.levin@oracle.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      8a0516ed
    • M
      mm: numa: do not dereference pmd outside of the lock during NUMA hinting fault · 5d833062
      Mel Gorman 提交于
      Automatic NUMA balancing depends on being able to protect PTEs to trap a
      fault and gather reference locality information.  Very broadly speaking
      it would mark PTEs as not present and use another bit to distinguish
      between NUMA hinting faults and other types of faults.  It was
      universally loved by everybody and caused no problems whatsoever.  That
      last sentence might be a lie.
      
      This series is very heavily based on patches from Linus and Aneesh to
      replace the existing PTE/PMD NUMA helper functions with normal change
      protections.  I did alter and add parts of it but I consider them
      relatively minor contributions.  At their suggestion, acked-bys are in
      there but I've no problem converting them to Signed-off-by if requested.
      
      AFAIK, this has received no testing on ppc64 and I'm depending on Aneesh
      for that.  I tested trinity under kvm-tool and passed and ran a few
      other basic tests.  At the time of writing, only the short-lived tests
      have completed but testing of V2 indicated that long-term testing had no
      surprises.  In most cases I'm leaving out detail as it's not that
      interesting.
      
      specjbb single JVM: There was negligible performance difference in the
      	benchmark itself for short runs. However, system activity is
      	higher and interrupts are much higher over time -- possibly TLB
      	flushes. Migrations are also higher. Overall, this is more overhead
      	but considering the problems faced with the old approach I think
      	we just have to suck it up and find another way of reducing the
      	overhead.
      
      specjbb multi JVM: Negligible performance difference to the actual benchmark
      	but like the single JVM case, the system overhead is noticeably
      	higher.  Again, interrupts are a major factor.
      
      autonumabench: This was all over the place and about all that can be
      	reasonably concluded is that it's different but not necessarily
      	better or worse.
      
      autonumabench
                                           3.18.0-rc5            3.18.0-rc5
                                       mmotm-20141119         protnone-v3r3
      User    NUMA01               32380.24 (  0.00%)    21642.92 ( 33.16%)
      User    NUMA01_THEADLOCAL    22481.02 (  0.00%)    22283.22 (  0.88%)
      User    NUMA02                3137.00 (  0.00%)     3116.54 (  0.65%)
      User    NUMA02_SMT            1614.03 (  0.00%)     1543.53 (  4.37%)
      System  NUMA01                 322.97 (  0.00%)     1465.89 (-353.88%)
      System  NUMA01_THEADLOCAL       91.87 (  0.00%)       49.32 ( 46.32%)
      System  NUMA02                  37.83 (  0.00%)       14.61 ( 61.38%)
      System  NUMA02_SMT               7.36 (  0.00%)        7.45 ( -1.22%)
      Elapsed NUMA01                 716.63 (  0.00%)      599.29 ( 16.37%)
      Elapsed NUMA01_THEADLOCAL      553.98 (  0.00%)      539.94 (  2.53%)
      Elapsed NUMA02                  83.85 (  0.00%)       83.04 (  0.97%)
      Elapsed NUMA02_SMT              86.57 (  0.00%)       79.15 (  8.57%)
      CPU     NUMA01                4563.00 (  0.00%)     3855.00 ( 15.52%)
      CPU     NUMA01_THEADLOCAL     4074.00 (  0.00%)     4136.00 ( -1.52%)
      CPU     NUMA02                3785.00 (  0.00%)     3770.00 (  0.40%)
      CPU     NUMA02_SMT            1872.00 (  0.00%)     1959.00 ( -4.65%)
      
      System CPU usage of NUMA01 is worse but it's an adverse workload on this
      machine so I'm reluctant to conclude that it's a problem that matters.  On
      the other workloads that are sensible on this machine, system CPU usage is
      great.  Overall time to complete the benchmark is comparable
      
                3.18.0-rc5  3.18.0-rc5
              mmotm-20141119protnone-v3r3
      User        59612.50    48586.44
      System        460.22     1537.45
      Elapsed      1442.20     1304.29
      
      NUMA alloc hit                 5075182     5743353
      NUMA alloc miss                      0           0
      NUMA interleave hit                  0           0
      NUMA alloc local               5075174     5743339
      NUMA base PTE updates        637061448   443106883
      NUMA huge PMD updates          1243434      864747
      NUMA page range updates     1273699656   885857347
      NUMA hint faults               1658116     1214277
      NUMA hint local faults          959487      754113
      NUMA hint local percent             57          62
      NUMA pages migrated            5467056    61676398
      
      The NUMA pages migrated look terrible but when I looked at a graph of the
      activity over time I see that the massive spike in migration activity was
      during NUMA01.  This correlates with high system CPU usage and could be
      simply down to bad luck but any modifications that affect that workload
      would be related to scan rates and migrations, not the protection
      mechanism.  For all other workloads, migration activity was comparable.
      
      Overall, headline performance figures are comparable but the overhead is
      higher, mostly in interrupts.  To some extent, higher overhead from this
      approach was anticipated but not to this degree.  It's going to be
      necessary to reduce this again with a separate series in the future.  It's
      still worth going ahead with this series though as it's likely to avoid
      constant headaches with Xen and is probably easier to maintain.
      
      This patch (of 10):
      
      A transhuge NUMA hinting fault may find the page is migrating and should
      wait until migration completes.  The check is race-prone because the pmd
      is deferenced outside of the page lock and while the race is tiny, it'll
      be larger if the PMD is cleared while marking PMDs for hinting fault.
      This patch closes the race.
      Signed-off-by: NMel Gorman <mgorman@suse.de>
      Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Dave Jones <davej@redhat.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Sasha Levin <sasha.levin@oracle.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      5d833062
  11. 12 2月, 2015 4 次提交
  12. 11 12月, 2014 1 次提交
  13. 30 10月, 2014 1 次提交
    • D
      mm, thp: fix collapsing of hugepages on madvise · 6d50e60c
      David Rientjes 提交于
      If an anonymous mapping is not allowed to fault thp memory and then
      madvise(MADV_HUGEPAGE) is used after fault, khugepaged will never
      collapse this memory into thp memory.
      
      This occurs because the madvise(2) handler for thp, hugepage_madvise(),
      clears VM_NOHUGEPAGE on the stack and it isn't stored in vma->vm_flags
      until the final action of madvise_behavior().  This causes the
      khugepaged_enter_vma_merge() to be a no-op in hugepage_madvise() when
      the vma had previously had VM_NOHUGEPAGE set.
      
      Fix this by passing the correct vma flags to the khugepaged mm slot
      handler.  There's no chance khugepaged can run on this vma until after
      madvise_behavior() returns since we hold mm->mmap_sem.
      
      It would be possible to clear VM_NOHUGEPAGE directly from vma->vm_flags
      in hugepage_advise(), but I didn't want to introduce special case
      behavior into madvise_behavior().  I think it's best to just let it
      always set vma->vm_flags itself.
      Signed-off-by: NDavid Rientjes <rientjes@google.com>
      Reported-by: NSuleiman Souhlal <suleiman@google.com>
      Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      6d50e60c