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Message-ID: <cd0a28f4b699024e611cb464a82a957c41217466.camel@kernel.org>
Date: Wed, 21 Nov 2018 06:21:19 -0500
From: Jeff Layton <jlayton@...nel.org>
To: kernel test robot <rong.a.chen@...el.com>,
NeilBrown <neilb@...e.com>
Cc: LKML <linux-kernel@...r.kernel.org>, lkp@...org
Subject: Re: [LKP] [fs/locks] 3c19f2312f: will-it-scale.per_thread_ops
-65.2% regression
On Wed, 2018-11-21 at 08:44 +0800, kernel test robot wrote:
> Greeting,
>
> FYI, we noticed a -65.2% regression of will-it-scale.per_thread_ops due to commit:
>
>
> commit: 3c19f2312f48a3d36a4e13f5072a6a95e755b3d5 ("fs/locks: always delete_block after waiting.")
> https://git.kernel.org/cgit/linux/kernel/git/jlayton/linux.git locks-4.21
>
> in testcase: will-it-scale
> on test machine: 88 threads Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz with 64G memory
> with following parameters:
>
> nr_task: 100%
> mode: thread
> test: lock1
> ucode: 0xb00002e
> cpufreq_governor: performance
>
> test-description: Will It Scale takes a testcase and runs it from 1 through to n parallel copies to see if the testcase will scale. It builds both a process and threads based test in order to see any differences between the two.
> test-url: https://github.com/antonblanchard/will-it-scale
>
>
Looking at the testcase, it just does whole-file exclusive fcntl
lock/unlock cycles. My gut feeling is that the reduction in wakeups is
probably worth some extra processing time here, but maybe it's possible
to do better.
If I'm looking at the profile below correctly, it looks like we're
spending quite a bit more time spinning on spinlocks. That makes some
sense since we're now taking the blocked_lock_lock in more cases.
I wonder if we could optimize that function away in some cases without
taking the lock? Maybe if fl_blocked_requests is empty and fl_blocker is
NULL? How to test those in a race-free way without taking the spinlock
may not be possible though.
Thoughts?
>
> Details are as below:
> -------------------------------------------------------------------------------------------------->
>
>
> To reproduce:
>
> git clone https://github.com/intel/lkp-tests.git
> cd lkp-tests
> bin/lkp install job.yaml # job file is attached in this email
> bin/lkp run job.yaml
>
> =========================================================================================
> compiler/cpufreq_governor/kconfig/mode/nr_task/rootfs/tbox_group/test/testcase/ucode:
> gcc-7/performance/x86_64-rhel-7.2/thread/100%/debian-x86_64-2018-04-03.cgz/lkp-bdw-ep3b/lock1/will-it-scale/0xb00002e
>
> commit:
> 816f2fb5a2 ("fs/locks: allow a lock request to block other requests.")
> 3c19f2312f ("fs/locks: always delete_block after waiting.")
>
> 816f2fb5a2fc678c 3c19f2312f48a3d36a4e13f507
> ---------------- --------------------------
> %stddev %change %stddev
> \ | \
> 71447 -65.2% 24854 will-it-scale.per_thread_ops
> 138940 -2.9% 134886 will-it-scale.time.involuntary_context_switches
> 279.85 -64.2% 100.29 will-it-scale.time.user_time
> 6287454 -65.2% 2187242 will-it-scale.workload
> 1.09 -0.7 0.42 mpstat.cpu.usr%
> 371230 ± 4% +9.5% 406403 softirqs.SCHED
> 1803 ± 16% +48.9% 2685 ± 8% numa-meminfo.node0.PageTables
> 2784 ± 10% -30.7% 1928 ± 12% numa-meminfo.node1.PageTables
> 224.55 -1.8% 220.57 turbostat.PkgWatt
> 7.70 -3.0% 7.47 turbostat.RAMWatt
> 450.50 ± 17% +49.0% 671.25 ± 8% numa-vmstat.node0.nr_page_table_pages
> 644147 ± 10% -19.8% 516646 ± 11% numa-vmstat.node0.numa_hit
> 639812 ± 10% -20.6% 508027 ± 12% numa-vmstat.node0.numa_local
> 696.25 ± 10% -30.7% 482.50 ± 12% numa-vmstat.node1.nr_page_table_pages
> 4617 +2.1% 4715 proc-vmstat.nr_inactive_anon
> 7097 +2.0% 7241 proc-vmstat.nr_mapped
> 20507 +7.0% 21934 ± 3% proc-vmstat.nr_shmem
> 4617 +2.1% 4715 proc-vmstat.nr_zone_inactive_anon
> 690109 +1.0% 696863 proc-vmstat.numa_hit
> 672911 +1.0% 679694 proc-vmstat.numa_local
> 23133 ± 2% +8.9% 25196 ± 4% proc-vmstat.pgactivate
> 607.03 ± 6% -16.0% 509.80 ± 12% sched_debug.cfs_rq:/.util_est_enqueued.avg
> 24.42 ± 28% +38.2% 33.75 ± 22% sched_debug.cpu.cpu_load[2].max
> 2.20 ± 28% +39.9% 3.08 ± 23% sched_debug.cpu.cpu_load[2].stddev
> 25.33 ± 12% +23.2% 31.21 ± 9% sched_debug.cpu.cpu_load[3].max
> 2.28 ± 21% +29.6% 2.95 ± 12% sched_debug.cpu.cpu_load[3].stddev
> 52140 ± 23% +37.1% 71510 ± 3% sched_debug.cpu.nr_switches.max
> 53379 ± 24% +46.4% 78158 ± 11% sched_debug.cpu.sched_count.max
> 7132 ± 12% +32.3% 9436 ± 15% sched_debug.cpu.sched_count.stddev
> 4.587e+12 -7.5% 4.245e+12 perf-stat.branch-instructions
> 0.24 -0.1 0.15 perf-stat.branch-miss-rate%
> 1.107e+10 -43.0% 6.312e+09 perf-stat.branch-misses
> 40.04 -2.0 38.01 perf-stat.cache-miss-rate%
> 8.415e+09 ± 2% -19.4% 6.782e+09 ± 6% perf-stat.cache-misses
> 2.101e+10 -15.1% 1.783e+10 ± 5% perf-stat.cache-references
> 3.85 +10.7% 4.26 perf-stat.cpi
> 0.00 ± 2% +0.0 0.00 ± 4% perf-stat.dTLB-load-miss-rate%
> 90399109 ± 2% +6.6% 96381582 ± 4% perf-stat.dTLB-load-misses
> 4.956e+12 -11.6% 4.38e+12 perf-stat.dTLB-loads
> 0.00 ± 8% +0.0 0.01 ± 24% perf-stat.dTLB-store-miss-rate%
> 8.789e+11 -61.0% 3.427e+11 perf-stat.dTLB-stores
> 80.76 -10.8 69.98 perf-stat.iTLB-load-miss-rate%
> 3.901e+09 -63.3% 1.43e+09 perf-stat.iTLB-load-misses
> 9.3e+08 ± 6% -34.0% 6.135e+08 ± 2% perf-stat.iTLB-loads
> 1.912e+13 -9.6% 1.728e+13 perf-stat.instructions
> 4901 +146.5% 12081 perf-stat.instructions-per-iTLB-miss
> 0.26 -9.6% 0.23 perf-stat.ipc
> 82.36 -3.7 78.70 perf-stat.node-store-miss-rate%
> 2.319e+09 -20.6% 1.842e+09 perf-stat.node-store-misses
> 3041599 +159.7% 7898884 perf-stat.path-length
> 61.02 ± 10% -61.0 0.00 perf-profile.calltrace.cycles-pp._raw_spin_lock.fcntl_setlk.do_fcntl.__x64_sys_fcntl.do_syscall_64
> 60.64 ± 10% -60.6 0.00 perf-profile.calltrace.cycles-pp.native_queued_spin_lock_slowpath._raw_spin_lock.fcntl_setlk.do_fcntl.__x64_sys_fcntl
> 98.79 +0.7 99.50 perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe
> 98.76 +0.7 99.49 perf-profile.calltrace.cycles-pp.do_syscall_64.entry_SYSCALL_64_after_hwframe
> 98.64 +0.8 99.44 perf-profile.calltrace.cycles-pp.__x64_sys_fcntl.do_syscall_64.entry_SYSCALL_64_after_hwframe
> 97.70 +1.5 99.16 perf-profile.calltrace.cycles-pp.do_fcntl.__x64_sys_fcntl.do_syscall_64.entry_SYSCALL_64_after_hwframe
> 97.41 +1.6 99.05 perf-profile.calltrace.cycles-pp.fcntl_setlk.do_fcntl.__x64_sys_fcntl.do_syscall_64.entry_SYSCALL_64_after_hwframe
> 35.73 ± 18% +62.7 98.45 perf-profile.calltrace.cycles-pp.do_lock_file_wait.fcntl_setlk.do_fcntl.__x64_sys_fcntl.do_syscall_64
> 0.00 +65.1 65.07 perf-profile.calltrace.cycles-pp.native_queued_spin_lock_slowpath._raw_spin_lock.locks_delete_block.do_lock_file_wait.fcntl_setlk
> 0.00 +65.3 65.28 perf-profile.calltrace.cycles-pp._raw_spin_lock.locks_delete_block.do_lock_file_wait.fcntl_setlk.do_fcntl
> 0.00 +65.3 65.31 perf-profile.calltrace.cycles-pp.locks_delete_block.do_lock_file_wait.fcntl_setlk.do_fcntl.__x64_sys_fcntl
> 1.13 ± 2% -0.7 0.43 perf-profile.children.cycles-pp.locks_alloc_lock
> 0.98 ± 2% -0.6 0.38 perf-profile.children.cycles-pp.kmem_cache_alloc
> 0.59 -0.4 0.23 ± 2% perf-profile.children.cycles-pp.syscall_return_via_sysret
> 0.53 -0.3 0.20 ± 2% perf-profile.children.cycles-pp.entry_SYSCALL_64
> 0.35 ± 11% -0.3 0.06 ± 9% perf-profile.children.cycles-pp.fput
> 0.41 ± 2% -0.3 0.15 ± 3% perf-profile.children.cycles-pp.file_has_perm
> 0.33 ± 2% -0.2 0.12 ± 6% perf-profile.children.cycles-pp.memset_erms
> 0.30 ± 3% -0.2 0.11 ± 3% perf-profile.children.cycles-pp.security_file_lock
> 0.25 ± 3% -0.2 0.10 ± 5% perf-profile.children.cycles-pp.security_file_fcntl
> 0.24 ± 2% -0.1 0.10 ± 4% perf-profile.children.cycles-pp._copy_from_user
> 0.22 ± 12% -0.1 0.07 ± 5% perf-profile.children.cycles-pp.__fget_light
> 0.21 ± 3% -0.1 0.08 ± 6% perf-profile.children.cycles-pp.avc_has_perm
> 0.20 ± 5% -0.1 0.08 perf-profile.children.cycles-pp.___might_sleep
> 0.16 ± 5% -0.1 0.06 perf-profile.children.cycles-pp.__fget
> 0.24 ± 3% -0.1 0.17 ± 2% perf-profile.children.cycles-pp.kmem_cache_free
> 0.12 ± 5% -0.1 0.05 perf-profile.children.cycles-pp.__might_sleep
> 0.24 ± 15% -0.1 0.18 perf-profile.children.cycles-pp.locks_insert_lock_ctx
> 0.11 ± 3% -0.0 0.10 ± 4% perf-profile.children.cycles-pp.locks_free_lock
> 98.83 +0.7 99.54 perf-profile.children.cycles-pp.entry_SYSCALL_64_after_hwframe
> 98.79 +0.7 99.52 perf-profile.children.cycles-pp.do_syscall_64
> 98.65 +0.8 99.44 perf-profile.children.cycles-pp.__x64_sys_fcntl
> 97.71 +1.5 99.17 perf-profile.children.cycles-pp.do_fcntl
> 97.42 +1.6 99.05 perf-profile.children.cycles-pp.fcntl_setlk
> 94.97 +3.0 97.98 perf-profile.children.cycles-pp._raw_spin_lock
> 93.97 +3.3 97.24 perf-profile.children.cycles-pp.native_queued_spin_lock_slowpath
> 35.74 ± 18% +62.7 98.46 perf-profile.children.cycles-pp.do_lock_file_wait
> 0.00 +65.3 65.31 perf-profile.children.cycles-pp.locks_delete_block
> 0.59 -0.4 0.23 ± 2% perf-profile.self.cycles-pp.syscall_return_via_sysret
> 0.53 -0.3 0.20 ± 2% perf-profile.self.cycles-pp.entry_SYSCALL_64
> 0.35 ± 10% -0.3 0.06 ± 9% perf-profile.self.cycles-pp.fput
> 1.00 ± 2% -0.3 0.74 perf-profile.self.cycles-pp._raw_spin_lock
> 0.38 ± 3% -0.2 0.14 perf-profile.self.cycles-pp.kmem_cache_alloc
> 0.32 ± 2% -0.2 0.12 ± 3% perf-profile.self.cycles-pp.memset_erms
> 0.20 ± 3% -0.1 0.08 ± 6% perf-profile.self.cycles-pp.avc_has_perm
> 0.20 ± 2% -0.1 0.08 ± 6% perf-profile.self.cycles-pp.posix_lock_inode
> 0.20 ± 6% -0.1 0.08 perf-profile.self.cycles-pp.___might_sleep
> 0.16 ± 4% -0.1 0.05 ± 9% perf-profile.self.cycles-pp.__fget
> 0.15 ± 8% -0.1 0.06 perf-profile.self.cycles-pp.fcntl_setlk
> 0.24 -0.1 0.15 ± 2% perf-profile.self.cycles-pp.kmem_cache_free
> 0.11 -0.1 0.03 ±100% perf-profile.self.cycles-pp.__x64_sys_fcntl
> 0.11 ± 4% -0.1 0.03 ±100% perf-profile.self.cycles-pp.__might_sleep
> 0.13 -0.1 0.05 perf-profile.self.cycles-pp.locks_alloc_lock
> 0.13 ± 5% -0.1 0.05 perf-profile.self.cycles-pp.file_has_perm
> 0.07 ± 7% -0.0 0.05 perf-profile.self.cycles-pp.locks_free_lock
> 93.64 +3.3 96.89 perf-profile.self.cycles-pp.native_queued_spin_lock_slowpath
>
>
>
> will-it-scale.per_thread_ops
>
> 75000 +-+-----------------------------------------------------------------+
> 70000 +-+.. .+.+.+..+.+.+.+.. .+. .+.. .+.+. .+. .+.+..+.+.+.+..+.|
> | + +. .+.+. + + +. + |
> 65000 +-+ + |
> 60000 +-+ |
> 55000 +-+ |
> 50000 +-+ |
> | |
> 45000 +-+ |
> 40000 +-+ |
> 35000 +-+ |
> 30000 +-+ |
> | |
> 25000 O-O O O O O O O O O O O O O O O O O O O O O O |
> 20000 +-+-----------------------------------------------------------------+
>
>
> will-it-scale.workload
>
> 6.5e+06 +-+---------------------------------------------------------------+
> |.+. .+.+.+.+ + +. .+. .+. .+.+. .+. .+.+ +.+..+.+ |
> 6e+06 +-+ +. +.+..+ + +. + +. |
> 5.5e+06 +-+ |
> | |
> 5e+06 +-+ |
> 4.5e+06 +-+ |
> | |
> 4e+06 +-+ |
> 3.5e+06 +-+ |
> | |
> 3e+06 +-+ |
> 2.5e+06 +-+ |
> O O O O O O O O O O O O O O O O O O O O O |
> 2e+06 +-+--------O-O----------------------------------------------------+
>
>
> will-it-scale.time.user_time
>
> 300 +-+-------------------------------------------------------------------+
> 280 +-+ .+.. .+. .+.. .+. .+.|
> |.+..+.+.+..+.+ + +.. .+.+.+..+.+.+..+.+.+..+.+ + +. |
> 260 +-+ +.+.+. |
> 240 +-+ |
> 220 +-+ |
> 200 +-+ |
> | |
> 180 +-+ |
> 160 +-+ |
> 140 +-+ O |
> 120 +-+ |
> O O O O O |
> 100 +-+ O O O O O O O O O O O O O O O O O |
> 80 +-+-------------------------------------------------------------------+
>
>
> [*] bisect-good sample
> [O] bisect-bad sample
>
>
>
> Disclaimer:
> Results have been estimated based on internal Intel analysis and are provided
> for informational purposes only. Any difference in system hardware or software
> design or configuration may affect actual performance.
>
>
> Thanks,
> Rong Chen
--
Jeff Layton <jlayton@...nel.org>
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