linux-kernel - Re: [LKP] [lkp] [f2fs] ec795418c4: fsmark.files_per

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Date:	Thu, 04 Aug 2016 10:44:20 -0700
From:	"Huang\, Ying" <ying.huang@...el.com>
To:	Jaegeuk Kim <jaegeuk@...nel.org>
Cc:	"Huang\, Ying" <ying.huang@...el.com>,
	kernel test robot <xiaolong.ye@...el.com>, <lkp@...org>,
	LKML <linux-kernel@...r.kernel.org>,
	<linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [LKP] [lkp] [f2fs] ec795418c4: fsmark.files_per_sec -36.3% regression

Jaegeuk Kim <jaegeuk@...nel.org> writes:

> Hi Huang,
>
> On Thu, Aug 04, 2016 at 10:00:41AM -0700, Huang, Ying wrote:
>> Hi, Jaegeuk,
>> 
>> "Huang, Ying" <ying.huang@...el.com> writes:
>> > Hi,
>> >
>> > I checked the comparison result below and found this is a regression for
>> > fsmark.files_per_sec, not fsmark.app_overhead.
>> >
>> > Best Regards,
>> > Huang, Ying
>> >
>> > kernel test robot <xiaolong.ye@...el.com> writes:
>> >
>> >> FYI, we noticed a -36.3% regression of fsmark.files_per_sec due to commit:
>> >>
>> >> commit ec795418c41850056feb956534edf059dc1155d4 ("f2fs: use percpu_rw_semaphore")
>> >> https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git dev-test
>> 
>> I found this has been merged by upstream.  Do you have some plan to fix
>> it?  Or you think the test itself has some problem?
>
> Sorry, too busy to take a look at this.
> The patch implements percpu_rw_semaphore which is intended to enhance FS
> scalability. Since I couldn't see any big regression in my test cases, could you
> check any debugging options which may give some overheads?

The kernel config related with F2FS is as follow in our test,

CONFIG_F2FS_FS=m
CONFIG_F2FS_STAT_FS=y
CONFIG_F2FS_FS_XATTR=y
CONFIG_F2FS_FS_POSIX_ACL=y
# CONFIG_F2FS_FS_SECURITY is not set
# CONFIG_F2FS_CHECK_FS is not set
# CONFIG_F2FS_FS_ENCRYPTION is not set
# CONFIG_F2FS_IO_TRACE is not set
# CONFIG_F2FS_FAULT_INJECTION is not set

What do you think we need to change?  Or do you mean some other
debugging options?  Anyway, you can check our kernel config attached.

> Let me recheck this with whole my tests.

Maybe you can try our kernel config?  Or if our kernel config is not
reasonable, can you help us to revise it?  The full kernel config we
used is attached with the email.

Best Regards,
Huang, Ying

> Thanks,
>
>> 
>> We have another 2 regressions
>> 
>> - [lkp] [f2fs] 3bdad3c7ee: aim7.jobs-per-min -25.3% regression
>> - [lkp] [f2fs] b93f771286: aim7.jobs-per-min -81.2% regression
>> 
>> they are merged by upstream now too.  So same questions for them too.
>> 
>> Best Regards,
>> Huang, Ying
>> 
>> >> in testcase: fsmark
>> >> on test machine: 72 threads Haswell-EP with 128G memory
>> >> with following parameters:
>> > cpufreq_governor=performance/disk=1SSD/filesize=8K/fs=f2fs/iterations=8/nr_directories=16d/nr_files_per_directory=256fpd/nr_threads=4/sync_method=fsyncBeforeClose/test_size=72G
>> >>
>> >>
>> >>
>> >> 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.
>> >>


Download attachment "kconfig" of type "application/octet-stream" (150952 bytes)