From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753175Ab1GED6n (ORCPT ); Mon, 4 Jul 2011 23:58:43 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:57736 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752852Ab1GED6l (ORCPT ); Mon, 4 Jul 2011 23:58:41 -0400 Date: Tue, 5 Jul 2011 11:58:13 +0800 From: Hu Tao To: Ingo Molnar Cc: Hidetoshi Seto , Peter Zijlstra , Paul Turner , linux-kernel@vger.kernel.org, Bharata B Rao , Dhaval Giani , Balbir Singh , Vaidyanathan Srinivasan , Srivatsa Vaddagiri , Kamalesh Babulal , Pavel Emelyanov Subject: Re: [patch 00/16] CFS Bandwidth Control v7 Message-ID: <20110705035813.GC4656@localhost.localdomain> References: <20110621071649.862846205@google.com> <4E01BE6B.2090701@jp.fujitsu.com> <1308830816.1022.112.camel@twins> <20110623124310.GA15430@elte.hu> <4E041C6A.4000701@jp.fujitsu.com> <20110626103526.GA11093@elte.hu> <20110629040521.GG4186@localhost.localdomain> <20110701122824.GE28008@elte.hu> MIME-Version: 1.0 In-Reply-To: <20110701122824.GE28008@elte.hu> User-Agent: Mutt/1.5.21 (2010-09-15) X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-07-05 11:57:58, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-07-05 11:58:02, Serialize complete at 2011-07-05 11:58:02 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 01, 2011 at 02:28:24PM +0200, Ingo Molnar wrote: > > * Hu Tao wrote: > > > > Yeah, these numbers look pretty good. Note that the percentages > > > in the third column (the amount of time that particular event was > > > measured) is pretty low, and it would be nice to eliminate it: > > > i.e. now that we know the ballpark figures do very precise > > > measurements that do not over-commit the PMU. > > > > > > One such measurement would be: > > > > > > -e cycles -e instructions -e branches > > > > > > This should also bring the stddev percentages down i think, to > > > below 0.1%. > > > > > > Another measurement would be to test not just the feature-enabled > > > but also the feature-disabled cost - so that we document the > > > rough overhead that users of this new scheduler feature should > > > expect. > > > > > > Organizing it into neat before/after numbers and percentages, > > > comparing it with noise (stddev) [i.e. determining that the > > > effect we measure is above noise] and putting it all into the > > > changelog would be the other goal of these measurements. > > > > Hi Ingo, > > > > I've tested pipe-test-100k in the following cases: base(no patch), > > with patch but feature-disabled, with patch and several > > periods(quota set to be a large value to avoid processes > > throttled), the result is: > > > > > > cycles instructions branches > > ------------------------------------------------------------------------------------------------------------------- > > base 7,526,317,497 8,666,579,347 1,771,078,445 > > +patch, cgroup not enabled 7,610,354,447 (1.12%) 8,569,448,982 (-1.12%) 1,751,675,193 (-0.11%) > > +patch, 10000000000/1000(quota/period) 7,856,873,327 (4.39%) 8,822,227,540 (1.80%) 1,801,766,182 (1.73%) > > +patch, 10000000000/10000(quota/period) 7,797,711,600 (3.61%) 8,754,747,746 (1.02%) 1,788,316,969 (0.97%) > > +patch, 10000000000/100000(quota/period) 7,777,784,384 (3.34%) 8,744,979,688 (0.90%) 1,786,319,566 (0.86%) > > +patch, 10000000000/1000000(quota/period) 7,802,382,802 (3.67%) 8,755,638,235 (1.03%) 1,788,601,070 (0.99%) > > ------------------------------------------------------------------------------------------------------------------- > > ok, i had a quick look at the stddev numbers as well and most seem > below the 0.1 range, well below the effects you managed to measure. > So i think this table is pretty accurate and we can rely on it for > analysis. > > So we've got a +1.1% incrase in overhead with cgroups disabled, while > the instruction count went down by 1.1%. Is this expected? If you > profile stalled cycles and use perf diff between base and patched > kernels, does it show you some new hotspot that causes the overhead? perf diff shows 0.43% increase in sched_clock, and 0.98% decrease in pipe_unlock. the complete output is attached. > > To better understand the reasons behind that result, could you try to > see whether the cycles count is stable across reboots as well, or > does it vary beyond the ~1% value that you measure? > > One thing that can help validating the measurements is to do: > > echo 1 > /proc/sys/vm/drop_caches > > Before testing. This helps re-establish the whole pagecache layout > (which gives a lot of the across-boot variability of such > measurements). I have tested three times for base and +patch,cgroup not enabled repectively (each time reboot, drop_caches then perf). the data seems stable comparing to those in the table above, see below: cycles instructions ------------------------------------------------------------------ base 7,526,317,497 8,666,579,347 base, drop_caches 7,518,958,711 (-0.10%) 8,634,136,901(-0.37%) base, drop_caches 7,526,419,287 (+0.00%) 8,641,162,766(-0.29%) base, drop_caches 7,491,864,402 (-0.46%) 8,624,760,925(-0.48%) cycles instructions -------------------------------------------------------------------------------------- +patch, cgroup disabled 7,610,354,447 8,569,448,982 +patch, cgroup disabled, drop_caches 7,574,623,093 (-0.47%) 8,572,061,001 (+0.03%) +patch, cgroup disabled, drop_caches 7,594,083,776 (-0.21%) 8,574,447,382 (+0.06%) +patch, cgroup disabled, drop_caches 7,584,913,316 (-0.33%) 8,574,734,269 (+0.06%) perf diff output: # Baseline Delta Shared Object Symbol # ........ .......... ................. ........................... # 0.00% +10.07% [kernel.kallsyms] [k] __lock_acquire 0.00% +5.90% [kernel.kallsyms] [k] lock_release 0.00% +4.86% [kernel.kallsyms] [k] trace_hardirqs_off_caller 0.00% +4.06% [kernel.kallsyms] [k] debug_smp_processor_id 0.00% +4.00% [kernel.kallsyms] [k] lock_acquire 0.00% +3.81% [kernel.kallsyms] [k] lock_acquired 0.00% +3.71% [kernel.kallsyms] [k] lock_is_held 0.00% +3.04% [kernel.kallsyms] [k] validate_chain 0.00% +2.68% [kernel.kallsyms] [k] check_chain_key 0.00% +2.41% [kernel.kallsyms] [k] trace_hardirqs_off 0.00% +2.01% [kernel.kallsyms] [k] trace_hardirqs_on_caller 2.04% -0.09% pipe-test-100k [.] main 0.00% +1.79% [kernel.kallsyms] [k] add_preempt_count 0.00% +1.67% [kernel.kallsyms] [k] lock_release_holdtime 0.00% +1.67% [kernel.kallsyms] [k] mutex_lock_nested 0.00% +1.61% [kernel.kallsyms] [k] pipe_read 0.00% +1.58% [kernel.kallsyms] [k] local_clock 1.13% +0.43% [kernel.kallsyms] [k] sched_clock 0.00% +1.52% [kernel.kallsyms] [k] sub_preempt_count 0.00% +1.39% [kernel.kallsyms] [k] _raw_spin_unlock_irqrestore 1.14% +0.15% libc-2.12.so [.] __GI___libc_read 0.00% +1.21% [kernel.kallsyms] [k] mark_lock 0.00% +1.06% [kernel.kallsyms] [k] __mutex_unlock_slowpath 0.00% +1.03% [kernel.kallsyms] [k] match_held_lock 0.00% +0.96% [kernel.kallsyms] [k] copy_user_generic_string 0.00% +0.93% [kernel.kallsyms] [k] schedule 0.00% +0.76% [kernel.kallsyms] [k] __list_del_entry 0.00% +0.73% [kernel.kallsyms] [k] enqueue_entity 0.00% +0.68% [kernel.kallsyms] [k] cpuacct_charge 0.00% +0.62% [kernel.kallsyms] [k] trace_preempt_off 0.00% +0.59% [kernel.kallsyms] [k] vfs_write 0.00% +0.56% [kernel.kallsyms] [k] trace_preempt_on 0.00% +0.56% [kernel.kallsyms] [k] system_call 0.00% +0.55% [kernel.kallsyms] [k] sys_read 0.00% +0.54% [kernel.kallsyms] [k] pipe_write 0.00% +0.53% [kernel.kallsyms] [k] get_parent_ip 0.00% +0.53% [kernel.kallsyms] [k] vfs_read 0.00% +0.53% [kernel.kallsyms] [k] put_lock_stats 0.56% -0.03% [kernel.kallsyms] [k] intel_pmu_enable_all 0.00% +0.51% [kernel.kallsyms] [k] fsnotify 0.72% -0.23% libc-2.12.so [.] __GI___libc_write 0.00% +0.49% [kernel.kallsyms] [k] do_sync_write 0.00% +0.48% [kernel.kallsyms] [k] trace_hardirqs_on 0.00% +0.48% [kernel.kallsyms] [k] do_sync_read 0.00% +0.45% [kernel.kallsyms] [k] dequeue_entity 0.00% +0.44% [kernel.kallsyms] [k] select_task_rq_fair 0.00% +0.44% [kernel.kallsyms] [k] update_curr 0.00% +0.43% [kernel.kallsyms] [k] fget_light 0.00% +0.42% [kernel.kallsyms] [k] do_raw_spin_trylock 0.00% +0.42% [kernel.kallsyms] [k] in_lock_functions 0.00% +0.40% [kernel.kallsyms] [k] find_next_bit 0.50% -0.11% [kernel.kallsyms] [k] intel_pmu_disable_all 0.00% +0.39% [kernel.kallsyms] [k] __list_add 0.00% +0.38% [kernel.kallsyms] [k] enqueue_task 0.00% +0.38% [kernel.kallsyms] [k] __might_sleep 0.00% +0.38% [kernel.kallsyms] [k] kill_fasync 0.00% +0.36% [kernel.kallsyms] [k] check_flags 0.00% +0.36% [kernel.kallsyms] [k] _raw_spin_unlock 0.00% +0.34% [kernel.kallsyms] [k] pipe_iov_copy_from_user 0.00% +0.33% [kernel.kallsyms] [k] check_preempt_curr 0.00% +0.32% [kernel.kallsyms] [k] system_call_after_swapgs 0.00% +0.32% [kernel.kallsyms] [k] mark_held_locks 0.00% +0.31% [kernel.kallsyms] [k] touch_atime 0.00% +0.30% [kernel.kallsyms] [k] account_entity_enqueue 0.00% +0.30% [kernel.kallsyms] [k] set_next_entity 0.00% +0.30% [kernel.kallsyms] [k] place_entity 0.00% +0.29% [kernel.kallsyms] [k] try_to_wake_up 0.00% +0.29% [kernel.kallsyms] [k] check_preempt_wakeup 0.00% +0.28% [kernel.kallsyms] [k] debug_lockdep_rcu_enabled 0.00% +0.28% [kernel.kallsyms] [k] cpumask_next_and 0.00% +0.28% [kernel.kallsyms] [k] __wake_up_common 0.00% +0.27% [kernel.kallsyms] [k] rb_erase 0.00% +0.26% [kernel.kallsyms] [k] ttwu_stat 0.00% +0.25% [kernel.kallsyms] [k] _raw_spin_unlock_irq 0.00% +0.25% [kernel.kallsyms] [k] pick_next_task_fair 0.00% +0.25% [kernel.kallsyms] [k] update_cfs_shares 0.00% +0.25% [kernel.kallsyms] [k] sysret_check 0.00% +0.25% [kernel.kallsyms] [k] lockdep_sys_exit_thunk 0.00% +0.25% [kernel.kallsyms] [k] _raw_spin_lock_irqsave 0.00% +0.24% [kernel.kallsyms] [k] get_lock_stats 0.00% +0.24% [kernel.kallsyms] [k] put_prev_task_fair 0.00% +0.24% [kernel.kallsyms] [k] trace_hardirqs_on_thunk 0.00% +0.24% [kernel.kallsyms] [k] __perf_event_task_sched_out 0.00% +0.24% [kernel.kallsyms] [k] ret_from_sys_call 0.00% +0.23% [kernel.kallsyms] [k] rcu_note_context_switch 0.00% +0.23% [kernel.kallsyms] [k] update_stats_wait_end 0.00% +0.23% [kernel.kallsyms] [k] file_update_time 0.35% -0.12% libc-2.12.so [.] __write_nocancel 0.00% +0.22% [kernel.kallsyms] [k] rw_verify_area 0.00% +0.21% [kernel.kallsyms] [k] mutex_unlock 0.00% +0.20% [kernel.kallsyms] [k] system_call_fastpath 0.00% +0.20% [kernel.kallsyms] [k] sys_write 0.09% +0.11% [kernel.kallsyms] [k] update_cfs_load 0.00% +0.20% [kernel.kallsyms] [k] time_hardirqs_off 0.10% +0.10% [kernel.kallsyms] [k] x86_pmu_disable 0.00% +0.19% [kernel.kallsyms] [k] clear_buddies 0.00% +0.19% [kernel.kallsyms] [k] activate_task 0.00% +0.18% [kernel.kallsyms] [k] enqueue_task_fair 0.00% +0.18% [kernel.kallsyms] [k] _raw_spin_lock 0.00% +0.18% [kernel.kallsyms] [k] ttwu_do_wakeup 0.00% +0.17% [kernel.kallsyms] [k] __srcu_read_lock 0.00% +0.17% [kernel.kallsyms] [k] prepare_to_wait 0.00% +0.16% [kernel.kallsyms] [k] debug_mutex_lock_common 0.00% +0.16% [kernel.kallsyms] [k] ttwu_activate 0.00% +0.16% [kernel.kallsyms] [k] time_hardirqs_on 0.00% +0.16% [kernel.kallsyms] [k] pipe_wait 0.00% +0.16% [kernel.kallsyms] [k] preempt_schedule 0.00% +0.16% [kernel.kallsyms] [k] debug_mutex_free_waiter 0.00% +0.15% [kernel.kallsyms] [k] __rcu_read_unlock 0.00% +0.14% [kernel.kallsyms] [k] account_cfs_rq_runtime 0.00% +0.14% [kernel.kallsyms] [k] perf_pmu_rotate_start 0.00% +0.14% [kernel.kallsyms] [k] pipe_lock 0.00% +0.14% [kernel.kallsyms] [k] __perf_event_task_sched_in 0.00% +0.14% [kernel.kallsyms] [k] __srcu_read_unlock 0.00% +0.13% [kernel.kallsyms] [k] perf_ctx_unlock 0.00% +0.13% [kernel.kallsyms] [k] __rcu_read_lock 0.00% +0.13% [kernel.kallsyms] [k] account_entity_dequeue 0.00% +0.12% [kernel.kallsyms] [k] __fsnotify_parent 0.00% +0.12% [kernel.kallsyms] [k] sched_clock_cpu 0.00% +0.12% [kernel.kallsyms] [k] current_fs_time 0.00% +0.11% [kernel.kallsyms] [k] _raw_spin_lock_irq 0.00% +0.11% [kernel.kallsyms] [k] mutex_remove_waiter 0.00% +0.11% [kernel.kallsyms] [k] autoremove_wake_function 0.00% +0.10% [kernel.kallsyms] [k] hrtick_start_fair 0.08% +0.03% pipe-test-100k [.] read@plt 0.00% +0.10% [kernel.kallsyms] [k] __bfs 0.00% +0.10% [kernel.kallsyms] [k] mnt_want_write 0.00% +0.09% [kernel.kallsyms] [k] __dequeue_entity 0.00% +0.09% [kernel.kallsyms] [k] do_raw_spin_unlock 0.00% +0.08% [kernel.kallsyms] [k] lockdep_sys_exit 0.00% +0.08% [kernel.kallsyms] [k] rb_next 0.00% +0.08% [kernel.kallsyms] [k] debug_mutex_unlock 0.00% +0.08% [kernel.kallsyms] [k] rb_insert_color 0.00% +0.08% [kernel.kallsyms] [k] update_rq_clock 0.00% +0.08% [kernel.kallsyms] [k] dequeue_task_fair 0.00% +0.07% [kernel.kallsyms] [k] finish_wait 0.00% +0.07% [kernel.kallsyms] [k] wakeup_preempt_entity 0.00% +0.07% [kernel.kallsyms] [k] debug_mutex_add_waiter 0.00% +0.07% [kernel.kallsyms] [k] ttwu_do_activate.clone.3 0.00% +0.07% [kernel.kallsyms] [k] generic_pipe_buf_map 0.00% +0.06% [kernel.kallsyms] [k] __wake_up_sync_key 0.00% +0.06% [kernel.kallsyms] [k] __mark_inode_dirty 0.04% +0.02% [kernel.kallsyms] [k] intel_pmu_nhm_enable_all 0.00% +0.05% [kernel.kallsyms] [k] timespec_trunc 0.00% +0.05% [kernel.kallsyms] [k] dequeue_task 0.00% +0.05% [kernel.kallsyms] [k] perf_pmu_disable 0.00% +0.05% [kernel.kallsyms] [k] apic_timer_interrupt 0.00% +0.05% [kernel.kallsyms] [k] current_kernel_time 0.05% pipe-test-100k [.] write@plt 0.00% +0.05% [kernel.kallsyms] [k] generic_pipe_buf_confirm 0.00% +0.04% [kernel.kallsyms] [k] __rcu_pending 0.00% +0.04% [kernel.kallsyms] [k] generic_pipe_buf_unmap 0.00% +0.04% [kernel.kallsyms] [k] anon_pipe_buf_release 0.00% +0.04% [kernel.kallsyms] [k] finish_task_switch 0.00% +0.04% [kernel.kallsyms] [k] perf_event_context_sched_in 0.00% +0.04% [kernel.kallsyms] [k] update_process_times 0.00% +0.04% [kernel.kallsyms] [k] do_timer 0.00% +0.04% [kernel.kallsyms] [k] trace_hardirqs_off_thunk 0.00% +0.03% [kernel.kallsyms] [k] run_timer_softirq 0.00% +0.02% [kernel.kallsyms] [k] default_wake_function 0.00% +0.02% [kernel.kallsyms] [k] hrtimer_interrupt 0.00% +0.02% [kernel.kallsyms] [k] timerqueue_add 0.00% +0.02% [kernel.kallsyms] [k] __do_softirq 0.00% +0.02% [kernel.kallsyms] [k] set_next_buddy 0.00% +0.02% [kernel.kallsyms] [k] resched_task 0.00% +0.02% [kernel.kallsyms] [k] task_tick_fair 0.00% +0.02% [kernel.kallsyms] [k] restore 0.00% +0.02% [kernel.kallsyms] [k] irq_exit 0.00% +0.02% [e1000e] [k] e1000_watchdog 0.00% +0.01% [kernel.kallsyms] [k] account_process_tick 0.00% +0.01% [kernel.kallsyms] [k] update_vsyscall 0.00% +0.01% [kernel.kallsyms] [k] rcu_enter_nohz 0.00% +0.01% [kernel.kallsyms] [k] hrtimer_run_pending 0.00% +0.01% [kernel.kallsyms] [k] calc_global_load 0.00% +0.01% [kernel.kallsyms] [k] account_system_time 0.00% +0.01% [kernel.kallsyms] [k] __run_hrtimer 0.99% -0.98% [kernel.kallsyms] [k] pipe_unlock 0.00% +0.01% [kernel.kallsyms] [k] irq_enter 0.00% +0.01% [kernel.kallsyms] [k] scheduler_tick 0.00% +0.01% [kernel.kallsyms] [k] mnt_want_write_file 0.00% +0.01% [kernel.kallsyms] [k] hrtimer_run_queues 0.01% [kernel.kallsyms] [k] sched_avg_update 0.00% [kernel.kallsyms] [k] rcu_check_callbacks 0.00% [kernel.kallsyms] [k] task_waking_fair 0.00% [kernel.kallsyms] [k] trace_softirqs_off 0.00% [kernel.kallsyms] [k] call_softirq 0.00% [kernel.kallsyms] [k] find_busiest_group 0.00% [kernel.kallsyms] [k] exit_idle 0.00% [kernel.kallsyms] [k] enqueue_hrtimer 0.00% [kernel.kallsyms] [k] hrtimer_forward 0.02% -0.02% [kernel.kallsyms] [k] x86_pmu_enable 0.01% [kernel.kallsyms] [k] do_softirq 0.00% [kernel.kallsyms] [k] calc_delta_mine 0.00% [kernel.kallsyms] [k] sched_slice 0.00% [kernel.kallsyms] [k] tick_sched_timer 0.00% [kernel.kallsyms] [k] irq_work_run 0.00% [kernel.kallsyms] [k] ktime_get 0.00% [kernel.kallsyms] [k] update_cpu_load 0.00% [kernel.kallsyms] [k] __remove_hrtimer 0.00% [kernel.kallsyms] [k] rcu_exit_nohz 0.00% [kernel.kallsyms] [k] clockevents_program_event and perf stat outputs: base, drop_caches: Performance counter stats for './pipe-test-100k' (50 runs): 3841.033842 task-clock # 0.576 CPUs utilized ( +- 0.06% ) 200,008 context-switches # 0.052 M/sec ( +- 0.00% ) 0 CPU-migrations # 0.000 M/sec ( +- 56.54% ) 135 page-faults # 0.000 M/sec ( +- 0.16% ) 7,518,958,711 cycles # 1.958 GHz ( +- 0.09% ) 2,676,161,995 stalled-cycles-frontend # 35.59% frontend cycles idle ( +- 0.17% ) 1,152,912,513 stalled-cycles-backend # 15.33% backend cycles idle ( +- 0.31% ) 8,634,136,901 instructions # 1.15 insns per cycle # 0.31 stalled cycles per insn ( +- 0.08% ) 1,764,912,243 branches # 459.489 M/sec ( +- 0.08% ) 35,531,303 branch-misses # 2.01% of all branches ( +- 0.12% ) 6.669821483 seconds time elapsed ( +- 0.03% ) base, drop_caches: Performance counter stats for './pipe-test-100k' (50 runs): 3840.203514 task-clock # 0.576 CPUs utilized ( +- 0.06% ) 200,009 context-switches # 0.052 M/sec ( +- 0.00% ) 0 CPU-migrations # 0.000 M/sec ( +- 60.19% ) 135 page-faults # 0.000 M/sec ( +- 0.18% ) 7,526,419,287 cycles # 1.960 GHz ( +- 0.08% ) 2,681,342,567 stalled-cycles-frontend # 35.63% frontend cycles idle ( +- 0.15% ) 1,159,603,323 stalled-cycles-backend # 15.41% backend cycles idle ( +- 0.36% ) 8,641,162,766 instructions # 1.15 insns per cycle # 0.31 stalled cycles per insn ( +- 0.07% ) 1,766,192,649 branches # 459.922 M/sec ( +- 0.07% ) 35,520,560 branch-misses # 2.01% of all branches ( +- 0.11% ) 6.667852851 seconds time elapsed ( +- 0.03% ) base, drop_caches: Performance counter stats for './pipe-test-100k' (50 runs): 3827.952520 task-clock # 0.575 CPUs utilized ( +- 0.06% ) 200,009 context-switches # 0.052 M/sec ( +- 0.00% ) 0 CPU-migrations # 0.000 M/sec ( +- 56.54% ) 135 page-faults # 0.000 M/sec ( +- 0.17% ) 7,491,864,402 cycles # 1.957 GHz ( +- 0.08% ) 2,664,949,808 stalled-cycles-frontend # 35.57% frontend cycles idle ( +- 0.16% ) 1,140,326,742 stalled-cycles-backend # 15.22% backend cycles idle ( +- 0.31% ) 8,624,760,925 instructions # 1.15 insns per cycle # 0.31 stalled cycles per insn ( +- 0.07% ) 1,761,666,011 branches # 460.211 M/sec ( +- 0.07% ) 34,655,390 branch-misses # 1.97% of all branches ( +- 0.12% ) 6.657224884 seconds time elapsed ( +- 0.03% ) +patch, cgroup disabled, drop_caches: Performance counter stats for './pipe-test-100k' (50 runs): 3857.191852 task-clock # 0.576 CPUs utilized ( +- 0.09% ) 200,008 context-switches # 0.052 M/sec ( +- 0.00% ) 0 CPU-migrations # 0.000 M/sec ( +- 42.86% ) 135 page-faults # 0.000 M/sec ( +- 0.19% ) 7,574,623,093 cycles # 1.964 GHz ( +- 0.10% ) 2,758,696,094 stalled-cycles-frontend # 36.42% frontend cycles idle ( +- 0.15% ) 1,239,909,382 stalled-cycles-backend # 16.37% backend cycles idle ( +- 0.38% ) 8,572,061,001 instructions # 1.13 insns per cycle # 0.32 stalled cycles per insn ( +- 0.08% ) 1,750,572,714 branches # 453.846 M/sec ( +- 0.08% ) 36,051,335 branch-misses # 2.06% of all branches ( +- 0.13% ) 6.691634724 seconds time elapsed ( +- 0.04% ) +patch, cgroup disabled, drop_caches: Performance counter stats for './pipe-test-100k' (50 runs): 3867.143019 task-clock # 0.577 CPUs utilized ( +- 0.10% ) 200,008 context-switches # 0.052 M/sec ( +- 0.00% ) 0 CPU-migrations # 0.000 M/sec ( +- 56.54% ) 135 page-faults # 0.000 M/sec ( +- 0.17% ) 7,594,083,776 cycles # 1.964 GHz ( +- 0.12% ) 2,775,221,867 stalled-cycles-frontend # 36.54% frontend cycles idle ( +- 0.19% ) 1,251,931,725 stalled-cycles-backend # 16.49% backend cycles idle ( +- 0.36% ) 8,574,447,382 instructions # 1.13 insns per cycle # 0.32 stalled cycles per insn ( +- 0.09% ) 1,751,600,855 branches # 452.944 M/sec ( +- 0.09% ) 36,098,438 branch-misses # 2.06% of all branches ( +- 0.16% ) 6.698065282 seconds time elapsed ( +- 0.05% ) +patch, cgroup disabled, drop_caches: Performance counter stats for './pipe-test-100k' (50 runs): 3857.654582 task-clock # 0.577 CPUs utilized ( +- 0.10% ) 200,009 context-switches # 0.052 M/sec ( +- 0.00% ) 0 CPU-migrations # 0.000 M/sec ( +- 78.57% ) 135 page-faults # 0.000 M/sec ( +- 0.23% ) 7,584,913,316 cycles # 1.966 GHz ( +- 0.11% ) 2,771,130,327 stalled-cycles-frontend # 36.53% frontend cycles idle ( +- 0.17% ) 1,263,203,011 stalled-cycles-backend # 16.65% backend cycles idle ( +- 0.40% ) 8,574,734,269 instructions # 1.13 insns per cycle # 0.32 stalled cycles per insn ( +- 0.09% ) 1,751,597,037 branches # 454.058 M/sec ( +- 0.09% ) 36,113,467 branch-misses # 2.06% of all branches ( +- 0.14% ) 6.688379749 seconds time elapsed ( +- 0.04% )