Re: [PATCH v2] Perf Bench: Locking Microbenchmark
From: Arnaldo Carvalho de Melo
Date: Fri Nov 21 2014 - 11:04:22 EST
Em Fri, Nov 21, 2014 at 12:57:06PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Thu, Nov 20, 2014 at 11:06:05AM -0800, Tuan Bui escreveu:
> > Subject: [PATCH] Perf Bench: Locking Microbenchmark
> > In response to this thread https://lkml.org/lkml/2014/2/11/93, this is
> > a micro benchmark that stresses locking contention in the kernel with
> > creat(2) system call by spawning multiple processes to spam this system
> > call. This workload generate similar results and contentions in AIM7
> > fserver workload but can generate outputs within seconds.
> > With the creat system call the contention vary on what locks are used
> > in the particular file system. I have ran this benchmark only on ext4
> > and xfs file system.
I noticed that if control+C it it leaves tons of files in the current
directory, can you please add code to make it handle this? I think that
it would also be better to create a temporary directory, etc.
And please take a look at the edited changelog below, to reflect those
changes on your next attempt to submit this patch, ok? I added an
Example so that people can now at a glance how it changes the existing
output for 'perf bench' and what is the output for 'perf bench locking'.
Subject: [PATCH] perf bench: Locking Microbenchmark
In response to this thread https://lkml.org/lkml/2014/2/11/93, this is
a micro benchmark that stresses locking contention in the kernel with
creat(2) system call by spawning multiple processes to spam this system
call. This workload generate similar results and contentions in AIM7
fserver workload but can generate outputs within seconds.
With the creat system call the contention vary on what locks are used
in the particular file system. I have ran this benchmark only on ext4
and xfs file system.
Running the creat workload on ext4 show contention in the mutex lock
that is used by ext4_orphan_add() and ext4_orphan_del() to add or delete
an inode from the list of inodes. At the same time running the creat
workload on xfs show contention in the spinlock that is used by
xsf_log_commit_cil() to commit a transaction to the Committed Item List.
Here is a comparison of this benchmark with AIM7 running fserver workload
at 500-1000 users along with a perf trace running on ext4 file system.
Test machine is a 8-sockets 80 cores Westmere system HT-off on v3.17-rc6.
AIM7 AIM7 perf-bench perf-bench
Users Jobs/min Jobs/min/child Ops/sec Ops/sec/child
500 119668.25 239.34 104249 208
600 126074.90 210.12 106136 176
700 128662.42 183.80 106175 151
800 119822.05 149.78 106290 132
900 106150.25 117.94 105230 116
1000 104681.29 104.68 106489 106
Perf report for AIM7 fserver:
14.51% reaim [kernel.kallsyms] [k] osq_lock
4.98% reaim reaim [.] add_long
4.98% reaim reaim [.] add_int
4.31% reaim [kernel.kallsyms] [k] mutex_spin_on_owner
Perf report of 'perf bench locking vfs'
22.37% locking-creat [kernel.kallsyms] [k] osq_lock
5.77% locking-creat [kernel.kallsyms] [k] mutex_spin_on_owner
5.31% locking-creat [kernel.kallsyms] [k] _raw_spin_lock
5.15% locking-creat [jbd2] [k] jbd2_journal_put_journal_head
[root@zoo ~]# perf bench
perf bench [<common options>] <collection> <benchmark>
# List of all available benchmark collections:
sched: Scheduler and IPC benchmarks
mem: Memory access benchmarks
numa: NUMA scheduling and MM benchmarks
futex: Futex stressing benchmarks
locking: Kernel locking benchmarks
all: All benchmarks
[root@zoo ~]# perf bench locking
# List of available benchmarks for collection 'locking':
vfs: Benchmark vfs using creat(2)
all: Run all benchmarks in this suite
[root@zoo ~]# perf bench locking vfs
100 processes: throughput = 342506 average opts/sec all processes
100 processes: throughput = 3425 average opts/sec per process
200 processes: throughput = 341309 average opts/sec all processes
200 processes: throughput = 1706 average opts/sec per process
Changes since v1:
- Added -j options to specified jobs per processes.
- Change name of microbenchmark from creat to vfs.
- Change all instances of threads to proccess.
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