From: Tejun Heo <tj@kernel.org>
To: Chris Mason <clm@fb.com>, Dexuan Cui <decui@microsoft.com>,
Theodore Ts'o <tytso@mit.edu>,
Andreas Dilger <adilger.kernel@dilger.ca>,
"linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: ext4: performance regression introduced by the cgroup writeback support
Date: Wed, 23 Sep 2015 14:53:37 -0400 [thread overview]
Message-ID: <20150923185337.GK26647@mtj.duckdns.org> (raw)
In-Reply-To: <20150923161359.GB25218@ret.masoncoding.com>
On Wed, Sep 23, 2015 at 12:13:59PM -0400, Chris Mason wrote:
> > The issue is: under high CPU and disk I/O pressure, *some* processes can suffer from a very slow write speed (e.g., <1MB/s or even only 20KB/s), while the normal write speed should be at least dozens of MB/s.
So, I think I know what caused this regression. Separate wb domains
shouldn't have been enabled on traditional hierarchies. It doesn't
work there and leads to multiple wb domains competing on the same
blkcg and the bw estimation would go completely haywire. Will update
soon.
Thanks.
--
tejun
next prev parent reply other threads:[~2015-09-23 18:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-23 13:49 ext4: performance regression introduced by the cgroup writeback support Dexuan Cui
2015-09-23 16:13 ` Chris Mason
2015-09-23 18:53 ` Tejun Heo [this message]
2015-09-24 0:15 ` Dexuan Cui
2015-09-24 7:26 ` Dexuan Cui
2015-09-24 0:12 ` Dexuan Cui
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