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  1. 30 7月, 2011 3 次提交
  3. 16 6月, 2011 2 次提交
  5. 15 6月, 2011 1 次提交
    • S
      rcu: Use softirq to address performance regression · 09223371
      由 Shaohua Li 提交于 
      Commit a26ac245(rcu: move TREE_RCU from softirq to kthread)
introduced performance regression. In an AIM7 test, this commit degraded
performance by about 40%.

The commit runs rcu callbacks in a kthread instead of softirq. We observed
high rate of context switch which is caused by this. Out test system has
64 CPUs and HZ is 1000, so we saw more than 64k context switch per second
which is caused by RCU's per-CPU kthread.  A trace showed that most of
the time the RCU per-CPU kthread doesn't actually handle any callbacks,
but instead just does a very small amount of work handling grace periods.
This means that RCU's per-CPU kthreads are making the scheduler do quite
a bit of work in order to allow a very small amount of RCU-related
processing to be done.

Alex Shi's analysis determined that this slowdown is due to lock
contention within the scheduler.  Unfortunately, as Peter Zijlstra points
out, the scheduler's real-time semantics require global action, which
means that this contention is inherent in real-time scheduling.  (Yes,
perhaps someone will come up with a workaround -- otherwise, -rt is not
going to do well on large SMP systems -- but this patch will work around
this issue in the meantime.  And "the meantime" might well be forever.)

This patch therefore re-introduces softirq processing to RCU, but only
for core RCU work.  RCU callbacks are still executed in kthread context,
so that only a small amount of RCU work runs in softirq context in the
common case.  This should minimize ksoftirqd execution, allowing us to
skip boosting of ksoftirqd for CONFIG_RCU_BOOST=y kernels.
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
Tested-by: N"Alex,Shi" <alex.shi@intel.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      09223371
  7. 10 6月, 2011 1 次提交
  9. 03 6月, 2011 4 次提交
  11. 02 6月, 2011 3 次提交
  13. 30 5月, 2011 1 次提交
  15. 28 5月, 2011 5 次提交
  17. 26 5月, 2011 3 次提交
    • A
      perf tools: Fix build on older systems · 75911c9b
      由 Arnaldo Carvalho de Melo 提交于 
      Where /usr/include/linux/const.h is not present, e.g. RHEL5.
Reported-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Link: http://lkml.kernel.org/n/tip-ypcw2mu0w7dl1rrc6ncz3pee@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      75911c9b
    • A
      perf symbols: Handle /proc/sys/kernel/kptr_restrict · ec80fde7
      由 Arnaldo Carvalho de Melo 提交于 
      Perf uses /proc/modules to figure out where kernel modules are loaded.

With the advent of kptr_restrict, non root users get zeroes for all module
start addresses.

So check if kptr_restrict is non zero and don't generate the syntethic
PERF_RECORD_MMAP events for them.

Warn the user about it in perf record and in perf report.

In perf report the reference relocation symbol being zero means that
kptr_restrict was set, thus /proc/kallsyms has only zeroed addresses, so don't
use it to fixup symbol addresses when using a valid kallsyms (in the buildid
cache) or vmlinux (in the vmlinux path) build-id located automatically or
specified by the user.

Provide an explanation about it in 'perf report' if kernel samples were taken,
checking if a suitable vmlinux or kallsyms was found/specified.

Restricted /proc/kallsyms don't go to the buildid cache anymore.

Example:

 [acme@emilia ~]$ perf record -F 100000 sleep 1

 WARNING: Kernel address maps (/proc/{kallsyms,modules}) are restricted, check
 /proc/sys/kernel/kptr_restrict.

 Samples in kernel functions may not be resolved if a suitable vmlinux file is
 not found in the buildid cache or in the vmlinux path.

 Samples in kernel modules won't be resolved at all.

 If some relocation was applied (e.g. kexec) symbols may be misresolved even
 with a suitable vmlinux or kallsyms file.

 [ perf record: Woken up 1 times to write data ]
 [ perf record: Captured and wrote 0.005 MB perf.data (~231 samples) ]
 [acme@emilia ~]$

 [acme@emilia ~]$ perf report --stdio
 Kernel address maps (/proc/{kallsyms,modules}) were restricted,
 check /proc/sys/kernel/kptr_restrict before running 'perf record'.

 If some relocation was applied (e.g. kexec) symbols may be misresolved.

 Samples in kernel modules can't be resolved as well.

 # Events: 13  cycles
 #
 # Overhead  Command      Shared Object                 Symbol
 # ........  .......  .................  .....................
 #
    20.24%    sleep  [kernel.kallsyms]  [k] page_fault
    20.04%    sleep  [kernel.kallsyms]  [k] filemap_fault
    19.78%    sleep  [kernel.kallsyms]  [k] __lru_cache_add
    19.69%    sleep  ld-2.12.so         [.] memcpy
    14.71%    sleep  [kernel.kallsyms]  [k] dput
     4.70%    sleep  [kernel.kallsyms]  [k] flush_signal_handlers
     0.73%    sleep  [kernel.kallsyms]  [k] perf_event_comm
     0.11%    sleep  [kernel.kallsyms]  [k] native_write_msr_safe

 #
 # (For a higher level overview, try: perf report --sort comm,dso)
 #
 [acme@emilia ~]$

This is because it found a suitable vmlinux (build-id checked) in
/lib/modules/2.6.39-rc7+/build/vmlinux (use -v in perf report to see the long
file name).

If we remove that file from the vmlinux path:

 [root@emilia ~]# mv /lib/modules/2.6.39-rc7+/build/vmlinux \
		     /lib/modules/2.6.39-rc7+/build/vmlinux.OFF
 [acme@emilia ~]$ perf report --stdio
 [kernel.kallsyms] with build id 57298cdbe0131f6871667ec0eaab4804dcf6f562
 not found, continuing without symbols

 Kernel address maps (/proc/{kallsyms,modules}) were restricted, check
 /proc/sys/kernel/kptr_restrict before running 'perf record'.

 As no suitable kallsyms nor vmlinux was found, kernel samples can't be
 resolved.

 Samples in kernel modules can't be resolved as well.

 # Events: 13  cycles
 #
 # Overhead  Command      Shared Object  Symbol
 # ........  .......  .................  ......
 #
    80.31%    sleep  [kernel.kallsyms]  [k] 0xffffffff8103425a
    19.69%    sleep  ld-2.12.so         [.] memcpy

 #
 # (For a higher level overview, try: perf report --sort comm,dso)
 #
 [acme@emilia ~]$
Reported-by: NStephane Eranian <eranian@google.com>
Suggested-by: NDavid Miller <davem@davemloft.net>
Cc: Dave Jones <davej@redhat.com>
Cc: David Miller <davem@davemloft.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Kees Cook <kees.cook@canonical.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Link: http://lkml.kernel.org/n/tip-mt512joaxxbhhp1odop04yit@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      ec80fde7
    • J
      perf: Remove duplicate headers · ea7659fb
      由 Jesper Juhl 提交于 
      Signed-off-by: NJesper Juhl <jj@chaosbits.net>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: trivial@kernel.org
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1105261011290.17400@swampdragon.chaosbits.netSigned-off-by: NIngo Molnar <mingo@elte.hu>
      ea7659fb
  19. 24 5月, 2011 1 次提交
  21. 23 5月, 2011 2 次提交
  23. 22 5月, 2011 6 次提交
  25. 21 5月, 2011 3 次提交
    • L
      sanitize <linux/prefetch.h> usage · 268bb0ce
      由 Linus Torvalds 提交于 
      Commit e66eed65 ("list: remove prefetching from regular list
iterators") removed the include of prefetch.h from list.h, which
uncovered several cases that had apparently relied on that rather
obscure header file dependency.

So this fixes things up a bit, using

   grep -L linux/prefetch.h $(git grep -l '[^a-z_]prefetchw*(' -- '*.[ch]')
   grep -L 'prefetchw*(' $(git grep -l 'linux/prefetch.h' -- '*.[ch]')

to guide us in finding files that either need <linux/prefetch.h>
inclusion, or have it despite not needing it.

There are more of them around (mostly network drivers), but this gets
many core ones.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      268bb0ce
    • S
      ktest: Allow options to be used by other options · 2a62512b
      由 Steven Rostedt 提交于 
      There are cases where one ktest option may be used within another
ktest option. Allow them to be reused just like config variables
but there are evaluated at time of test not config processing time.

Thus having something like:

MAKE_CMD = make ARCH=${ARCH}

TEST_START
ARCH = powerpc

TEST_START
ARCH = arm

Will have the arch defined for each test iteration.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      2a62512b
    • S
      ktest: Create variables for the ktest config files · 77d942ce
      由 Steven Rostedt 提交于 
      I found that I constantly reuse information for each test case.
It would be nice to just define a variable to reuse.

For example I may have:

TEST_START
[...]
TEST = ssh root@mybox /path/to/my/script

TEST_START
[...]
TEST = ssh root@mybox /path/to/my/script

[etc]

The issue is, I may wont to change that script or one of the other
fields. Then I need to update each line individually.

With the addition of config variables (variables only used during parsing
the config) we can simplify the config files. These variables can
also be defined multiple times and each time the new value will
overwrite the old value.

The convention to use a config variable over a ktest option is to use :=
instead of =.

Now we could do:

USER := root
TARGET := mybox
TEST_SCRIPT := /path/to/my/script
TEST_CASE := ${USER}@${TARGET} ${TEST_SCRIPT}

TEST_START
[...]
TEST = ${TEST_CASE}

TEST_START
[...]
TEST = ${TEST_CASE}

[etc]

Now we just need to update the variables at the top.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      77d942ce
  27. 20 5月, 2011 4 次提交
  29. 19 5月, 2011 1 次提交
    • I
      perf stat: Add more cache-miss percentage printouts · c3305257
      由 Ingo Molnar 提交于 
      Print out the cache-miss percentage as well if the cache refs were
collected, for all the generic cache event types.

Before:

   11,103,723,230 dTLB-loads                #  622.471 M/sec                    ( +-  0.30% )
       87,065,337 dTLB-load-misses          #    4.881 M/sec                    ( +-  0.90% )

After:

   11,353,713,242 dTLB-loads                #  626.020 M/sec                    ( +-  0.35% )
      113,393,472 dTLB-load-misses          #    1.00% of all dTLB cache hits   ( +-  0.49% )

Also ASCII color highlight too high percentages, them when it's executed on the console.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/n/tip-lkhwxsevdbd9a8nymx0vxc3y@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@elte.hu>
      c3305257