1. 02 Mar, 2017 2 commits
  2. 09 Feb, 2016 1 commit
    • Mel Gorman's avatar
      sched/debug: Make schedstats a runtime tunable that is disabled by default · cb251765
      Mel Gorman authored
      schedstats is very useful during debugging and performance tuning but it
      incurs overhead to calculate the stats. As such, even though it can be
      disabled at build time, it is often enabled as the information is useful.
      
      This patch adds a kernel command-line and sysctl tunable to enable or
      disable schedstats on demand (when it's built in). It is disabled
      by default as someone who knows they need it can also learn to enable
      it when necessary.
      
      The benefits are dependent on how scheduler-intensive the workload is.
      If it is then the patch reduces the number of cycles spent calculating
      the stats with a small benefit from reducing the cache footprint of the
      scheduler.
      
      These measurements were taken from a 48-core 2-socket
      machine with Xeon(R) E5-2670 v3 cpus although they were also tested on a
      single socket machine 8-core machine with Intel i7-3770 processors.
      
      netperf-tcp
                                 4.5.0-rc1             4.5.0-rc1
                                   vanilla          nostats-v3r1
      Hmean    64         560.45 (  0.00%)      575.98 (  2.77%)
      Hmean    128        766.66 (  0.00%)      795.79 (  3.80%)
      Hmean    256        950.51 (  0.00%)      981.50 (  3.26%)
      Hmean    1024      1433.25 (  0.00%)     1466.51 (  2.32%)
      Hmean    2048      2810.54 (  0.00%)     2879.75 (  2.46%)
      Hmean    3312      4618.18 (  0.00%)     4682.09 (  1.38%)
      Hmean    4096      5306.42 (  0.00%)     5346.39 (  0.75%)
      Hmean    8192     10581.44 (  0.00%)    10698.15 (  1.10%)
      Hmean    16384    18857.70 (  0.00%)    18937.61 (  0.42%)
      
      Small gains here, UDP_STREAM showed nothing intresting and neither did
      the TCP_RR tests. The gains on the 8-core machine were very similar.
      
      tbench4
                                       4.5.0-rc1             4.5.0-rc1
                                         vanilla          nostats-v3r1
      Hmean    mb/sec-1         500.85 (  0.00%)      522.43 (  4.31%)
      Hmean    mb/sec-2         984.66 (  0.00%)     1018.19 (  3.41%)
      Hmean    mb/sec-4        1827.91 (  0.00%)     1847.78 (  1.09%)
      Hmean    mb/sec-8        3561.36 (  0.00%)     3611.28 (  1.40%)
      Hmean    mb/sec-16       5824.52 (  0.00%)     5929.03 (  1.79%)
      Hmean    mb/sec-32      10943.10 (  0.00%)    10802.83 ( -1.28%)
      Hmean    mb/sec-64      15950.81 (  0.00%)    16211.31 (  1.63%)
      Hmean    mb/sec-128     15302.17 (  0.00%)    15445.11 (  0.93%)
      Hmean    mb/sec-256     14866.18 (  0.00%)    15088.73 (  1.50%)
      Hmean    mb/sec-512     15223.31 (  0.00%)    15373.69 (  0.99%)
      Hmean    mb/sec-1024    14574.25 (  0.00%)    14598.02 (  0.16%)
      Hmean    mb/sec-2048    13569.02 (  0.00%)    13733.86 (  1.21%)
      Hmean    mb/sec-3072    12865.98 (  0.00%)    13209.23 (  2.67%)
      
      Small gains of 2-4% at low thread counts and otherwise flat.  The
      gains on the 8-core machine were slightly different
      
      tbench4 on 8-core i7-3770 single socket machine
      Hmean    mb/sec-1        442.59 (  0.00%)      448.73 (  1.39%)
      Hmean    mb/sec-2        796.68 (  0.00%)      794.39 ( -0.29%)
      Hmean    mb/sec-4       1322.52 (  0.00%)     1343.66 (  1.60%)
      Hmean    mb/sec-8       2611.65 (  0.00%)     2694.86 (  3.19%)
      Hmean    mb/sec-16      2537.07 (  0.00%)     2609.34 (  2.85%)
      Hmean    mb/sec-32      2506.02 (  0.00%)     2578.18 (  2.88%)
      Hmean    mb/sec-64      2511.06 (  0.00%)     2569.16 (  2.31%)
      Hmean    mb/sec-128     2313.38 (  0.00%)     2395.50 (  3.55%)
      Hmean    mb/sec-256     2110.04 (  0.00%)     2177.45 (  3.19%)
      Hmean    mb/sec-512     2072.51 (  0.00%)     2053.97 ( -0.89%)
      
      In constract, this shows a relatively steady 2-3% gain at higher thread
      counts. Due to the nature of the patch and the type of workload, it's
      not a surprise that the result will depend on the CPU used.
      
      hackbench-pipes
                               4.5.0-rc1             4.5.0-rc1
                                 vanilla          nostats-v3r1
      Amean    1        0.0637 (  0.00%)      0.0660 ( -3.59%)
      Amean    4        0.1229 (  0.00%)      0.1181 (  3.84%)
      Amean    7        0.1921 (  0.00%)      0.1911 (  0.52%)
      Amean    12       0.3117 (  0.00%)      0.2923 (  6.23%)
      Amean    21       0.4050 (  0.00%)      0.3899 (  3.74%)
      Amean    30       0.4586 (  0.00%)      0.4433 (  3.33%)
      Amean    48       0.5910 (  0.00%)      0.5694 (  3.65%)
      Amean    79       0.8663 (  0.00%)      0.8626 (  0.43%)
      Amean    110      1.1543 (  0.00%)      1.1517 (  0.22%)
      Amean    141      1.4457 (  0.00%)      1.4290 (  1.16%)
      Amean    172      1.7090 (  0.00%)      1.6924 (  0.97%)
      Amean    192      1.9126 (  0.00%)      1.9089 (  0.19%)
      
      Some small gains and losses and while the variance data is not included,
      it's close to the noise. The UMA machine did not show anything particularly
      different
      
      pipetest
                                   4.5.0-rc1             4.5.0-rc1
                                     vanilla          nostats-v2r2
      Min         Time        4.13 (  0.00%)        3.99 (  3.39%)
      1st-qrtle   Time        4.38 (  0.00%)        4.27 (  2.51%)
      2nd-qrtle   Time        4.46 (  0.00%)        4.39 (  1.57%)
      3rd-qrtle   Time        4.56 (  0.00%)        4.51 (  1.10%)
      Max-90%     Time        4.67 (  0.00%)        4.60 (  1.50%)
      Max-93%     Time        4.71 (  0.00%)        4.65 (  1.27%)
      Max-95%     Time        4.74 (  0.00%)        4.71 (  0.63%)
      Max-99%     Time        4.88 (  0.00%)        4.79 (  1.84%)
      Max         Time        4.93 (  0.00%)        4.83 (  2.03%)
      Mean        Time        4.48 (  0.00%)        4.39 (  1.91%)
      Best99%Mean Time        4.47 (  0.00%)        4.39 (  1.91%)
      Best95%Mean Time        4.46 (  0.00%)        4.38 (  1.93%)
      Best90%Mean Time        4.45 (  0.00%)        4.36 (  1.98%)
      Best50%Mean Time        4.36 (  0.00%)        4.25 (  2.49%)
      Best10%Mean Time        4.23 (  0.00%)        4.10 (  3.13%)
      Best5%Mean  Time        4.19 (  0.00%)        4.06 (  3.20%)
      Best1%Mean  Time        4.13 (  0.00%)        4.00 (  3.39%)
      
      Small improvement and similar gains were seen on the UMA machine.
      
      The gain is small but it stands to reason that doing less work in the
      scheduler is a good thing. The downside is that the lack of schedstats and
      tracepoints may be surprising to experts doing performance analysis until
      they find the existence of the schedstats= parameter or schedstats sysctl.
      It will be automatically activated for latencytop and sleep profiling to
      alleviate the problem. For tracepoints, there is a simple warning as it's
      not safe to activate schedstats in the context when it's known the tracepoint
      may be wanted but is unavailable.
      Signed-off-by: default avatarMel Gorman <mgorman@techsingularity.net>
      Reviewed-by: default avatarMatt Fleming <matt@codeblueprint.co.uk>
      Reviewed-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Mike Galbraith <mgalbraith@suse.de>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/1454663316-22048-1-git-send-email-mgorman@techsingularity.netSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      cb251765
  3. 04 Jun, 2014 1 commit
  4. 31 Oct, 2011 1 commit
    • Paul Gortmaker's avatar
      kernel: Map most files to use export.h instead of module.h · 9984de1a
      Paul Gortmaker authored
      The changed files were only including linux/module.h for the
      EXPORT_SYMBOL infrastructure, and nothing else.  Revector them
      onto the isolated export header for faster compile times.
      
      Nothing to see here but a whole lot of instances of:
      
        -#include <linux/module.h>
        +#include <linux/export.h>
      
      This commit is only changing the kernel dir; next targets
      will probably be mm, fs, the arch dirs, etc.
      Signed-off-by: default avatarPaul Gortmaker <paul.gortmaker@windriver.com>
      9984de1a
  5. 13 Sep, 2011 1 commit
  6. 31 Mar, 2011 1 commit
  7. 13 Jan, 2011 1 commit
  8. 12 Nov, 2010 1 commit
  9. 30 Mar, 2010 1 commit
    • Tejun Heo's avatar
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking... · 5a0e3ad6
      Tejun Heo authored
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
      
      percpu.h is included by sched.h and module.h and thus ends up being
      included when building most .c files.  percpu.h includes slab.h which
      in turn includes gfp.h making everything defined by the two files
      universally available and complicating inclusion dependencies.
      
      percpu.h -> slab.h dependency is about to be removed.  Prepare for
      this change by updating users of gfp and slab facilities include those
      headers directly instead of assuming availability.  As this conversion
      needs to touch large number of source files, the following script is
      used as the basis of conversion.
      
        http://userweb.kernel.org/~tj/misc/slabh-sweep.py
      
      The script does the followings.
      
      * Scan files for gfp and slab usages and update includes such that
        only the necessary includes are there.  ie. if only gfp is used,
        gfp.h, if slab is used, slab.h.
      
      * When the script inserts a new include, it looks at the include
        blocks and try to put the new include such that its order conforms
        to its surrounding.  It's put in the include block which contains
        core kernel includes, in the same order that the rest are ordered -
        alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
        doesn't seem to be any matching order.
      
      * If the script can't find a place to put a new include (mostly
        because the file doesn't have fitting include block), it prints out
        an error message indicating which .h file needs to be added to the
        file.
      
      The conversion was done in the following steps.
      
      1. The initial automatic conversion of all .c files updated slightly
         over 4000 files, deleting around 700 includes and adding ~480 gfp.h
         and ~3000 slab.h inclusions.  The script emitted errors for ~400
         files.
      
      2. Each error was manually checked.  Some didn't need the inclusion,
         some needed manual addition while adding it to implementation .h or
         embedding .c file was more appropriate for others.  This step added
         inclusions to around 150 files.
      
      3. The script was run again and the output was compared to the edits
         from #2 to make sure no file was left behind.
      
      4. Several build tests were done and a couple of problems were fixed.
         e.g. lib/decompress_*.c used malloc/free() wrappers around slab
         APIs requiring slab.h to be added manually.
      
      5. The script was run on all .h files but without automatically
         editing them as sprinkling gfp.h and slab.h inclusions around .h
         files could easily lead to inclusion dependency hell.  Most gfp.h
         inclusion directives were ignored as stuff from gfp.h was usually
         wildly available and often used in preprocessor macros.  Each
         slab.h inclusion directive was examined and added manually as
         necessary.
      
      6. percpu.h was updated not to include slab.h.
      
      7. Build test were done on the following configurations and failures
         were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
         distributed build env didn't work with gcov compiles) and a few
         more options had to be turned off depending on archs to make things
         build (like ipr on powerpc/64 which failed due to missing writeq).
      
         * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
         * powerpc and powerpc64 SMP allmodconfig
         * sparc and sparc64 SMP allmodconfig
         * ia64 SMP allmodconfig
         * s390 SMP allmodconfig
         * alpha SMP allmodconfig
         * um on x86_64 SMP allmodconfig
      
      8. percpu.h modifications were reverted so that it could be applied as
         a separate patch and serve as bisection point.
      
      Given the fact that I had only a couple of failures from tests on step
      6, I'm fairly confident about the coverage of this conversion patch.
      If there is a breakage, it's likely to be something in one of the arch
      headers which should be easily discoverable easily on most builds of
      the specific arch.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Guess-its-ok-by: default avatarChristoph Lameter <cl@linux-foundation.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      5a0e3ad6
  10. 11 Feb, 2009 1 commit
  11. 10 Dec, 2008 1 commit
  12. 29 Apr, 2008 1 commit
  13. 19 Apr, 2008 1 commit
  14. 25 Jan, 2008 1 commit