[fs] e691fc4583e: -59.7% dbench.throughput-MB/sec

From: Fengguang Wu
Date: Thu Aug 07 2014 - 06:56:43 EST


Hi Neil,

We noticed the below dbench regression on

git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
commit e691fc4583e512f936bd04efb870815fe1ed750d ("fs: allow ->d_manage() to declare -EISDIR in rcu_walk mode.")

test case: ivb44/dbench/100%

53bcc0567b8c520 e691fc4583e512f936bd04efb
--------------- -------------------------
25957 Â 0% -59.7% 10460 Â 4% TOTAL dbench.throughput-MB/sec
0.00 +Inf% 24.33 Â31% TOTAL perf-profile.cpu-cycles._raw_spin_lock.lockref_get_not_dead.unlazy_walk.lookup_fast.link_path_walk
15.14 Â 0% -82.1% 2.71 Â25% TOTAL perf-profile.cpu-cycles.copy_user_enhanced_fast_string.copy_page_to_iter.generic_file_read_iter.new_sync_read.vfs_read
0.00 +Inf% 4.33 Â35% TOTAL perf-profile.cpu-cycles.lockref_put_or_lock.dput.link_path_walk.path_openat.do_filp_open
0.00 +Inf% 4.35 Â36% TOTAL perf-profile.cpu-cycles.lockref_get_not_dead.unlazy_walk.lookup_fast.link_path_walk.path_openat
0.00 +Inf% 5.06 Â36% TOTAL perf-profile.cpu-cycles.lockref_put_or_lock.dput.link_path_walk.path_lookupat.filename_lookup
1.11 Â 1% -100.0% 0.00 Â 0% TOTAL perf-profile.cpu-cycles._raw_spin_lock.dcache_readdir.iterate_dir.sys_getdents.system_call_fastpath
0.00 +Inf% 5.10 Â36% TOTAL perf-profile.cpu-cycles.lockref_get_not_dead.unlazy_walk.lookup_fast.link_path_walk.path_lookupat
0.00 +Inf% 11.19 Â30% TOTAL perf-profile.cpu-cycles._raw_spin_lock.lockref_put_or_lock.dput.link_path_walk.path_openat
0.00 +Inf% 12.85 Â31% TOTAL perf-profile.cpu-cycles._raw_spin_lock.lockref_put_or_lock.dput.link_path_walk.path_lookupat
2.00 Â 0% -79.5% 0.41 Â26% TOTAL perf-profile.cpu-cycles.find_get_entry.pagecache_get_page.generic_file_read_iter.new_sync_read.vfs_read
2.01 Â 3% -74.0% 0.52 Â17% TOTAL perf-profile.cpu-cycles.rcu_nocb_kthread.kthread.ret_from_fork
8.70 Â 1% -77.5% 1.96 Â24% TOTAL perf-profile.cpu-cycles.copy_user_enhanced_fast_string.iov_iter_copy_from_user_atomic.generic_perform_write.__generic_file_write_iter.generic_file_write_iter
1.20 Â 0% -75.9% 0.29 Â25% TOTAL perf-profile.cpu-cycles.get_empty_filp.path_openat.do_filp_open.do_sys_open.sys_openat
1.11 Â 3% -72.9% 0.30 Â22% TOTAL perf-profile.cpu-cycles.selinux_inode_permission.security_inode_permission.__inode_permission.inode_permission.link_path_walk
2.03 Â 1% -69.2% 0.63 Â21% TOTAL perf-profile.cpu-cycles.__vdso_gettimeofday
1.52 Â 4% -67.6% 0.49 Â13% TOTAL perf-profile.cpu-cycles.avc_has_perm_noaudit.selinux_inode_permission.security_inode_permission.__inode_permission.inode_permission
47938419 Â 0% -60.6% 18877399 Â 3% TOTAL proc-vmstat.pgalloc_dma32
9.25e+08 Â 0% -59.7% 3.728e+08 Â 3% TOTAL proc-vmstat.pgalloc_normal
22194267 Â 0% -59.3% 9023662 Â 3% TOTAL proc-vmstat.pgactivate
4.53e+08 Â 0% -58.0% 1.904e+08 Â 2% TOTAL numa-numastat.node1.local_node
4.53e+08 Â 0% -58.0% 1.904e+08 Â 2% TOTAL numa-numastat.node1.numa_hit
2987057 Â 0% -56.3% 1306633 Â 2% TOTAL softirqs.RCU
964655 Â14% -47.3% 508785 Â23% TOTAL cpuidle.C3-IVT.time
0.32 Â 5% -37.3% 0.20 Â12% TOTAL turbostat.%c1
69254 Â 6% -32.7% 46602 Â 9% TOTAL cpuidle.C6-IVT.usage
2724 Â15% -32.3% 1843 Â 6% TOTAL cpuidle.C3-IVT.usage
6665511 Â11% -31.9% 4540015 Â 8% TOTAL cpuidle.C1E-IVT.time
26138868 Â11% -27.6% 18932437 Â17% TOTAL cpuidle.C1-IVT.time
6013 Â 9% -28.3% 4311 Â18% TOTAL proc-vmstat.pgmigrate_success
6013 Â 9% -28.3% 4311 Â18% TOTAL proc-vmstat.numa_pages_migrated
48751 Â 4% -18.3% 39837 Â 6% TOTAL proc-vmstat.numa_hint_faults
1849 Â 2% -14.9% 1573 Â 3% TOTAL numa-vmstat.node0.nr_alloc_batch
48570 Â 4% -16.9% 40343 Â 6% TOTAL proc-vmstat.numa_pte_updates
17191 Â 6% -15.3% 14566 Â14% TOTAL cpuidle.C1E-IVT.usage
85893 Â 3% +12.4% 96578 Â 4% TOTAL meminfo.Committed_AS
29718 Â 4% -8.0% 27337 Â 2% TOTAL proc-vmstat.numa_hint_faults_local
13612 Â 3% -10.4% 12195 Â 3% TOTAL slabinfo.kmalloc-192.num_objs
13611 Â 3% -10.4% 12195 Â 3% TOTAL slabinfo.kmalloc-192.active_objs
9469 Â 0% -62.3% 3574 Â 3% TOTAL time.user_time
1365218 Â 1% -44.4% 759678 Â 1% TOTAL time.involuntary_context_switches
4818 Â 1% -38.7% 2954 Â 1% TOTAL vmstat.system.cs
 0% -37.0%  1% TOTAL turbostat.RAM_W
23661 Â 0% +28.8% 30466 Â 0% TOTAL time.system_time
158133 Â 8% -16.6% 131932 Â 9% TOTAL time.voluntary_context_switches
196790 Â 7% -15.8% 165728 Â 8% TOTAL time.minor_page_faults
 0% -10.5%  0% TOTAL turbostat.Cor_W
 0% -9.8%  0% TOTAL turbostat.Pkg_W
4599 Â 0% +2.7% 4724 Â 0% TOTAL time.percent_of_cpu_this_job_got
54951 Â 0% -1.7% 54021 Â 0% TOTAL vmstat.system.in

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,
Fengguang
echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu10/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu11/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu12/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu13/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu14/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu15/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu16/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu17/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu18/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu19/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu2/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu20/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu21/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu22/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu23/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu24/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu25/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu26/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu27/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu28/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu29/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu3/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu30/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu31/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu32/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu33/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu34/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu35/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu36/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu37/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu38/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu39/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu4/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu40/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu41/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu42/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu43/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu44/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu45/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu46/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu47/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu5/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu6/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu7/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu8/cpufreq/scaling_governor
echo performance > /sys/devices/system/cpu/cpu9/cpufreq/scaling_governor
dbench 48 -c /usr/share/dbench/client.txt
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