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  1. 29 4月, 2011 4 次提交
    • I
      perf stat: Analyze front-end and back-end stall counts · d3d1e86d
      由 Ingo Molnar 提交于 
      Sample output:

 Performance counter stats for './loop_1b':

        873.691065 task-clock               #    1.000 CPUs utilized
                 1 context-switches         #    0.000 M/sec
                 1 CPU-migrations           #    0.000 M/sec
                96 page-faults              #    0.000 M/sec
     2,012,637,222 cycles                   #    2.304 GHz                      (66.58%)
     1,001,397,911 stalled-cycles-frontend  #   49.76% frontend cycles idle     (66.58%)
         7,523,398 stalled-cycles-backend   #    0.37%  backend cycles idle     (66.76%)
     2,004,551,046 instructions             #    1.00  insns per cycle
                                            #    0.50  stalled cycles per insn  (66.80%)
     1,001,304,992 branches                 # 1146.063 M/sec                    (66.76%)
            39,453 branch-misses            #    0.00% of all branches          (66.64%)

        0.874046121  seconds time elapsed

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-7y40wib8n003io7hjpn1dsrm@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@elte.hu>
      d3d1e86d
    • I
      perf tools: Add front-end and back-end stalled cycles support · 129c04cb
      由 Ingo Molnar 提交于 
      Update perf tooling to deal with front-end and back-end stalled cycles events.

Add both the default 'perf stat' output.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-7y40wib8n002io7hjpn1dsrm@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@elte.hu>
      129c04cb
    • I
      perf, x86: Add new stalled cycles events for Intel and AMD CPUs · 91fc4cc0
      由 Ingo Molnar 提交于 
      Extend the Intel and AMD event definitions with generic front-end and
back-end stall events.

( These are only approximations - suggestions are welcome for better events. )

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-7y40wib8n001io7hjpn1dsrm@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@elte.hu>
      91fc4cc0
    • I
      perf events: Add generic front-end and back-end stalled cycle event definitions · 8f622422
      由 Ingo Molnar 提交于 
      Add two generic hardware events: front-end and back-end stalled cycles.

These events measure conditions when the CPU is executing code but its
capabilities are not fully utilized. Understanding such situations and
analyzing them is an important sub-task of code optimization workflows.

Both events limit performance: most front end stalls tend to be caused
by branch misprediction or instruction fetch cachemisses, backend
stalls can be caused by various resource shortages or inefficient
instruction scheduling.

Front-end stalls are the more important ones: code cannot run fast
if the instruction stream is not being kept up.

An over-utilized back-end can cause front-end stalls and thus
has to be kept an eye on as well.

The exact composition is very program logic and instruction mix
dependent.

We use the terms 'stall', 'front-end' and 'back-end' loosely and
try to use the best available events from specific CPUs that
approximate these concepts.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-7y40wib8n000io7hjpn1dsrm@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@elte.hu>
      8f622422
  3. 28 4月, 2011 3 次提交
    • I
      perf stat: Fix compatibility behavior · ede70290
      由 Ingo Molnar 提交于 
      Instead of failing on an unknown event, when new perf stat is run on
older kernels:

  $ ./perf stat true
  Error: open_counter returned with 22 (Invalid argument). /bin/dmesg
  may provide additional information.

  Fatal: Not all events could be opened.

Just ignore EINVAL and ENOSYS, we'll print the results as not counted:

 Performance counter stats for 'true':

          0.239483 task-clock               #    0.493 CPUs utilized
                 0 context-switches         #    0.000 M/sec
                 0 CPU-migrations           #    0.000 M/sec
                86 page-faults              #    0.359 M/sec
           704,766 cycles                   #    2.943 GHz
     <not counted> stalled-cycles
           381,961 instructions             #    0.54  insns per cycle
            69,626 branches                 #  290.735 M/sec
             4,594 branch-misses            #    6.60% of all branches

        0.000485883  seconds time elapsed

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-7y40wib8n1eqio5hjpn3dsrm@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@elte.hu>
      ede70290
    • I
      perf stat: Add --sync/-S option · f9cef0a9
      由 Ingo Molnar 提交于 
      --sync will tell perf stat to run sync() before starting a command.

This allows IO-heavy tests to be used with --repeat, without one
iteration impacting the other.

Elapsed time will stabilize for example:

  before:        3.971525714  seconds time elapsed  ( +-  8.56% )
  after:         3.211098537  seconds time elapsed  ( +-  1.52% )

So measurements will be more accurate.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-7y40wib8n1eqio7hjpn1dsrm@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@elte.hu>
      f9cef0a9
    • I
      perf event, x86: Use better stalled cycles metric · 8a850cad
      由 Ingo Molnar 提交于 
      Use the UOPS_EXECUTED.*,c=1,i=1 event on Intel CPUs - it is a rather
good indicator of CPU execution stalls, more sensitive and more inclusive
than the 0xa2 resource stalls event (which does not count nearly as many
stall types).

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-7y40wib8n1eqio7hjpn2dsrm@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@elte.hu>
      8a850cad
  5. 27 4月, 2011 18 次提交
  7. 26 4月, 2011 11 次提交
  9. 24 4月, 2011 4 次提交