> -----Original Message----- > From: Tejun Heo [mailto:htejun@xxxxxxxxx] On Behalf Of Tejun Heo > Sent: Thursday, September 24, 2015 2:54 > To: Chris Mason <clm@xxxxxx>; Dexuan Cui <decui@xxxxxxxxxxxxx>; > Theodore Ts'o <tytso@xxxxxxx>; Andreas Dilger <adilger.kernel@xxxxxxxxx>; > linux-ext4@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx > 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-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
