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Message-ID: <08750e508f1643b2a2c0bb495c91d450@SIXPR30MB031.064d.mgd.msft.net> Date: Thu, 24 Sep 2015 00:15:37 +0000 From: Dexuan Cui <decui@...rosoft.com> To: Tejun Heo <tj@...nel.org>, Chris Mason <clm@...com>, Theodore Ts'o <tytso@....edu>, Andreas Dilger <adilger.kernel@...ger.ca>, "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>, "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: RE: ext4: performance regression introduced by the cgroup writeback support > -----Original Message----- > From: Tejun Heo [mailto:htejun@...il.com] On Behalf Of Tejun Heo > Sent: Thursday, September 24, 2015 2:54 > To: Chris Mason <clm@...com>; Dexuan Cui <decui@...rosoft.com>; > Theodore Ts'o <tytso@....edu>; Andreas Dilger <adilger.kernel@...ger.ca>; > linux-ext4@...r.kernel.org; linux-fsdevel@...r.kernel.org; linux- > kernel@...r.kernel.org > Subject: Re: ext4: performance regression introduced by the cgroup writeback > support > > 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 Thanks a lot for the quick fix, Tejun! I'll test the fix. I'll report back in case it can't fix the issue --I think this is unlikely. :-) -- Dexuan -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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