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SubjectRe: [PATCH v2] Perf Bench: Locking Microbenchmark
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On Fri, 2014-11-21 at 13:04 -0300, Arnaldo Carvalho de Melo wrote:
> 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.
>

Thank you for the suggestion Arnaldo. I will implement code to handle
control+C using a temp directory.

> 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'.
>
> - Arnaldo
>

I will definitely include your edited changelog on my next attempt to
submit this patch. Thank you.

-Tuan


> 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
> ...
>
> Example:
>
> [root@zoo ~]# perf bench
> Usage:
> perf bench [<common options>] <collection> <benchmark>
> [<options>]
>
> # 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
> <SNIP>
>
> 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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