From: David Sterba <dsterba@suse.cz>
To: kernel test robot <oliver.sang@intel.com>
Cc: "Josef Bacik" <josef@toxicpanda.com>,
"David Sterba" <dsterba@suse.com>,
"René Rebe" <rene@exactcode.de>,
LKML <linux-kernel@vger.kernel.org>,
lkp@lists.01.org, lkp@intel.com, ying.huang@intel.com,
feng.tang@intel.com, zhengjun.xing@intel.com,
linux-btrfs@vger.kernel.org
Subject: Re: [btrfs] e076ab2a2c: fio.write_iops -18.3% regression
Date: Tue, 12 Jan 2021 16:45:29 +0100 [thread overview]
Message-ID: <20210112154529.GT6430@twin.jikos.cz> (raw)
In-Reply-To: <20210112153614.GA2015@xsang-OptiPlex-9020>
On Tue, Jan 12, 2021 at 11:36:14PM +0800, kernel test robot wrote:
>
> Greeting,
>
> FYI, we noticed a -18.3% regression of fio.write_iops due to commit:
>
>
> commit: e076ab2a2ca70a0270232067cd49f76cd92efe64 ("btrfs: shrink delalloc pages instead of full inodes")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>
>
> in testcase: fio-basic
> on test machine: 192 threads Intel(R) Xeon(R) CPU @ 2.20GHz with 192G memory
> with following parameters:
>
> disk: 1SSD
> fs: btrfs
> runtime: 300s
> nr_task: 8
> rw: randwrite
> bs: 4k
> ioengine: sync
> test_size: 256g
Though I do a similar test (emulating bit torrent workload), it's a bit
extreme as it's 4k synchronous on a huge file. It always takes a lot of
time but could point out some concurrency issues namely on faster
devices. There are 8 threads possibly competing for the same inode lock
or other locks related to it.
The mentioned commit fixed another perf regression on a much more common
workload (untgrring files), so at this point drop in this fio workload
is inevitable.
next prev parent reply other threads:[~2021-01-12 15:48 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-12 15:36 [btrfs] e076ab2a2c: fio.write_iops -18.3% regression kernel test robot
2021-01-12 15:45 ` David Sterba [this message]
2021-01-13 5:58 ` [LKP] " Xing Zhengjun
2021-01-14 22:50 ` David Sterba
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