1. 19 10月, 2010 1 次提交
    • Y
      block: fix accounting bug on cross partition merges · 7681bfee
      Yasuaki Ishimatsu 提交于
      /proc/diskstats would display a strange output as follows.
      
      $ cat /proc/diskstats |grep sda
         8       0 sda 90524 7579 102154 20464 0 0 0 0 0 14096 20089
         8       1 sda1 19085 1352 21841 4209 0 0 0 0 4294967064 15689 4293424691
                                                      ~~~~~~~~~~
         8       2 sda2 71252 3624 74891 15950 0 0 0 0 232 23995 1562390
         8       3 sda3 54 487 2188 92 0 0 0 0 0 88 92
         8       4 sda4 4 0 8 0 0 0 0 0 0 0 0
         8       5 sda5 81 2027 2130 138 0 0 0 0 0 87 137
      
      Its reason is the wrong way of accounting hd_struct->in_flight. When a bio is
      merged into a request belongs to different partition by ELEVATOR_FRONT_MERGE.
      
      The detailed root cause is as follows.
      
      Assuming that there are two partition, sda1 and sda2.
      
      1. A request for sda2 is in request_queue. Hence sda1's hd_struct->in_flight
         is 0 and sda2's one is 1.
      
              | hd_struct->in_flight
         ---------------------------
         sda1 |          0
         sda2 |          1
         ---------------------------
      
      2. A bio belongs to sda1 is issued and is merged into the request mentioned on
         step1 by ELEVATOR_BACK_MERGE. The first sector of the request is changed
         from sda2 region to sda1 region. However the two partition's
         hd_struct->in_flight are not changed.
      
              | hd_struct->in_flight
         ---------------------------
         sda1 |          0
         sda2 |          1
         ---------------------------
      
      3. The request is finished and blk_account_io_done() is called. In this case,
         sda2's hd_struct->in_flight, not a sda1's one, is decremented.
      
              | hd_struct->in_flight
         ---------------------------
         sda1 |         -1
         sda2 |          1
         ---------------------------
      
      The patch fixes the problem by caching the partition lookup
      inside the request structure, hence making sure that the increment
      and decrement will always happen on the same partition struct. This
      also speeds up IO with accounting enabled, since it cuts down on
      the number of lookups we have to do.
      
      When reloading partition tables, quiesce IO to ensure that no
      request references to the partition struct exists. When it is safe
      to free the partition table, the IO for that device is restarted
      again.
      Signed-off-by: NYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
      Cc: stable@kernel.org
      Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
      7681bfee
  2. 15 10月, 2010 1 次提交
  3. 14 10月, 2010 1 次提交
  4. 25 9月, 2010 1 次提交
  5. 16 9月, 2010 1 次提交
  6. 15 9月, 2010 2 次提交
    • W
      block, partition: add partition_meta_info to hd_struct · 6d1d8050
      Will Drewry 提交于
      I'm reposting this patch series as v4 since there have been no additional
      comments, and I cleaned up one extra bit of unneeded code (in 3/3). The patches
      are against Linus's tree: 2bfc96a1
      (2.6.36-rc3).
      
      Would this patchset be suitable for inclusion in an mm branch?
      
      This changes adds a partition_meta_info struct which itself contains a
      union of structures that provide partition table specific metadata.
      
      This change leaves the union empty. The subsequent patch includes an
      implementation for CONFIG_EFI_PARTITION-based metadata.
      Signed-off-by: NWill Drewry <wad@chromium.org>
      Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
      6d1d8050
    • N
      block: fix an address space warning in blk-map.c · 14417799
      Namhyung Kim 提交于
      Change type of 2nd parameter of blk_rq_aligned() into unsigned long
      and remove unnecessary casting. Now we can call it with 'uaddr'
      instead of 'ubuf' in __blk_rq_map_user() so that it can remove
      following warnings from sparse:
      
       block/blk-map.c:57:31: warning: incorrect type in argument 2 (different address spaces)
       block/blk-map.c:57:31:    expected void *addr
       block/blk-map.c:57:31:    got void [noderef] <asn:1>*ubuf
      
      However blk_rq_map_kern() needs one more local variable to handle it.
      Signed-off-by: NNamhyung Kim <namhyung@gmail.com>
      Signed-off-by: NJens Axboe <jaxboe@fusionio.com>
      14417799
  7. 11 9月, 2010 2 次提交
  8. 21 8月, 2010 2 次提交
  9. 18 8月, 2010 10 次提交
    • N
      fs: scale files_lock · 6416ccb7
      Nick Piggin 提交于
      fs: scale files_lock
      
      Improve scalability of files_lock by adding per-cpu, per-sb files lists,
      protected with an lglock. The lglock provides fast access to the per-cpu lists
      to add and remove files. It also provides a snapshot of all the per-cpu lists
      (although this is very slow).
      
      One difficulty with this approach is that a file can be removed from the list
      by another CPU. We must track which per-cpu list the file is on with a new
      variale in the file struct (packed into a hole on 64-bit archs). Scalability
      could suffer if files are frequently removed from different cpu's list.
      
      However loads with frequent removal of files imply short interval between
      adding and removing the files, and the scheduler attempts to avoid moving
      processes too far away. Also, even in the case of cross-CPU removal, the
      hardware has much more opportunity to parallelise cacheline transfers with N
      cachelines than with 1.
      
      A worst-case test of 1 CPU allocating files subsequently being freed by N CPUs
      degenerates to contending on a single lock, which is no worse than before. When
      more than one CPU are allocating files, even if they are always freed by
      different CPUs, there will be more parallelism than the single-lock case.
      
      Testing results:
      
      On a 2 socket, 8 core opteron, I measure the number of times the lock is taken
      to remove the file, the number of times it is removed by the same CPU that
      added it, and the number of times it is removed by the same node that added it.
      
      Booting:    locks=  25049 cpu-hits=  23174 (92.5%) node-hits=  23945 (95.6%)
      kbuild -j16 locks=2281913 cpu-hits=2208126 (96.8%) node-hits=2252674 (98.7%)
      dbench 64   locks=4306582 cpu-hits=4287247 (99.6%) node-hits=4299527 (99.8%)
      
      So a file is removed from the same CPU it was added by over 90% of the time.
      It remains within the same node 95% of the time.
      
      Tim Chen ran some numbers for a 64 thread Nehalem system performing a compile.
      
                      throughput
      2.6.34-rc2      24.5
      +patch          24.9
      
                      us      sys     idle    IO wait (in %)
      2.6.34-rc2      51.25   28.25   17.25   3.25
      +patch          53.75   18.5    19      8.75
      
      So significantly less CPU time spent in kernel code, higher idle time and
      slightly higher throughput.
      
      Single threaded performance difference was within the noise of microbenchmarks.
      That is not to say penalty does not exist, the code is larger and more memory
      accesses required so it will be slightly slower.
      
      Cc: linux-kernel@vger.kernel.org
      Cc: Tim Chen <tim.c.chen@linux.intel.com>
      Cc: Andi Kleen <ak@linux.intel.com>
      Signed-off-by: NNick Piggin <npiggin@kernel.dk>
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      6416ccb7
    • N
      lglock: introduce special lglock and brlock spin locks · 2dc91abe
      Nick Piggin 提交于
      lglock: introduce special lglock and brlock spin locks
      
      This patch introduces "local-global" locks (lglocks). These can be used to:
      
      - Provide fast exclusive access to per-CPU data, with exclusive access to
        another CPU's data allowed but possibly subject to contention, and to provide
        very slow exclusive access to all per-CPU data.
      - Or to provide very fast and scalable read serialisation, and to provide
        very slow exclusive serialisation of data (not necessarily per-CPU data).
      
      Brlocks are also implemented as a short-hand notation for the latter use
      case.
      
      Thanks to Paul for local/global naming convention.
      
      Cc: linux-kernel@vger.kernel.org
      Cc: Al Viro <viro@ZenIV.linux.org.uk>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Signed-off-by: NNick Piggin <npiggin@kernel.dk>
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      2dc91abe
    • N
      tty: fix fu_list abuse · d996b62a
      Nick Piggin 提交于
      tty: fix fu_list abuse
      
      tty code abuses fu_list, which causes a bug in remount,ro handling.
      
      If a tty device node is opened on a filesystem, then the last link to the inode
      removed, the filesystem will be allowed to be remounted readonly. This is
      because fs_may_remount_ro does not find the 0 link tty inode on the file sb
      list (because the tty code incorrectly removed it to use for its own purpose).
      This can result in a filesystem with errors after it is marked "clean".
      
      Taking idea from Christoph's initial patch, allocate a tty private struct
      at file->private_data and put our required list fields in there, linking
      file and tty. This makes tty nodes behave the same way as other device nodes
      and avoid meddling with the vfs, and avoids this bug.
      
      The error handling is not trivial in the tty code, so for this bugfix, I take
      the simple approach of using __GFP_NOFAIL and don't worry about memory errors.
      This is not a problem because our allocator doesn't fail small allocs as a rule
      anyway. So proper error handling is left as an exercise for tty hackers.
      
      [ Arguably filesystem's device inode would ideally be divorced from the
      driver's pseudo inode when it is opened, but in practice it's not clear whether
      that will ever be worth implementing. ]
      
      Cc: linux-kernel@vger.kernel.org
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
      Cc: Greg Kroah-Hartman <gregkh@suse.de>
      Signed-off-by: NNick Piggin <npiggin@kernel.dk>
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      d996b62a
    • N
      fs: cleanup files_lock locking · ee2ffa0d
      Nick Piggin 提交于
      fs: cleanup files_lock locking
      
      Lock tty_files with a new spinlock, tty_files_lock; provide helpers to
      manipulate the per-sb files list; unexport the files_lock spinlock.
      
      Cc: linux-kernel@vger.kernel.org
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
      Acked-by: NAndi Kleen <ak@linux.intel.com>
      Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
      Signed-off-by: NNick Piggin <npiggin@kernel.dk>
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      ee2ffa0d
    • N
      fs: fs_struct rwlock to spinlock · 2a4419b5
      Nick Piggin 提交于
      fs: fs_struct rwlock to spinlock
      
      struct fs_struct.lock is an rwlock with the read-side used to protect root and
      pwd members while taking references to them. Taking a reference to a path
      typically requires just 2 atomic ops, so the critical section is very small.
      Parallel read-side operations would have cacheline contention on the lock, the
      dentry, and the vfsmount cachelines, so the rwlock is unlikely to ever give a
      real parallelism increase.
      
      Replace it with a spinlock to avoid one or two atomic operations in typical
      path lookup fastpath.
      Signed-off-by: NNick Piggin <npiggin@kernel.dk>
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      2a4419b5
    • C
      remove SWRITE* I/O types · 9cb569d6
      Christoph Hellwig 提交于
      These flags aren't real I/O types, but tell ll_rw_block to always
      lock the buffer instead of giving up on a failed trylock.
      
      Instead add a new write_dirty_buffer helper that implements this semantic
      and use it from the existing SWRITE* callers.  Note that the ll_rw_block
      code had a bug where it didn't promote WRITE_SYNC_PLUG properly, which
      this patch fixes.
      
      In the ufs code clean up the helper that used to call ll_rw_block
      to mirror sync_dirty_buffer, which is the function it implements for
      compound buffers.
      Signed-off-by: NChristoph Hellwig <hch@lst.de>
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      9cb569d6
    • C
      kill BH_Ordered flag · 87e99511
      Christoph Hellwig 提交于
      Instead of abusing a buffer_head flag just add a variant of
      sync_dirty_buffer which allows passing the exact type of write
      flag required.
      Signed-off-by: NChristoph Hellwig <hch@lst.de>
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      87e99511
    • E
      spi.h: missing kernel-doc notation, please fix · 5c79a5ae
      Ernst Schwab 提交于
      Added comments in kernel-doc notation for previously added struct fields.
      Signed-off-by: NErnst Schwab <eschwab@online.de>
      Acked-by: NRandy Dunlap <rdunlap@xenotime.net>
      Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>
      5c79a5ae
    • D
      Make do_execve() take a const filename pointer · d7627467
      David Howells 提交于
      Make do_execve() take a const filename pointer so that kernel_execve() compiles
      correctly on ARM:
      
      arch/arm/kernel/sys_arm.c:88: warning: passing argument 1 of 'do_execve' discards qualifiers from pointer target type
      
      This also requires the argv and envp arguments to be consted twice, once for
      the pointer array and once for the strings the array points to.  This is
      because do_execve() passes a pointer to the filename (now const) to
      copy_strings_kernel().  A simpler alternative would be to cast the filename
      pointer in do_execve() when it's passed to copy_strings_kernel().
      
      do_execve() may not change any of the strings it is passed as part of the argv
      or envp lists as they are some of them in .rodata, so marking these strings as
      const should be fine.
      
      Further kernel_execve() and sys_execve() need to be changed to match.
      
      This has been test built on x86_64, frv, arm and mips.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      Tested-by: NRalf Baechle <ralf@linux-mips.org>
      Acked-by: NRussell King <rmk+kernel@arm.linux.org.uk>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d7627467
    • R
      VIDEO: amba clcd: don't disable an already disabled clock · 99c796df
      Russell King 提交于
      Fix the clock enable/disable tracking in the AMBA CLCD driver so
      that the driver doesn't try to disable an already disabled clock,
      thereby causing the clock (if shared) to become unbalanced.
      
      This resolves a problem with CLCD on LPC32xx ARM platforms.
      Reported-by: NKevin Wells <wellsk40@gmail.com>
      Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
      99c796df
  10. 15 8月, 2010 2 次提交
  11. 14 8月, 2010 3 次提交
  12. 13 8月, 2010 3 次提交
  13. 12 8月, 2010 11 次提交