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From: Alex Shi <lkml.alex@gmail.com>
Newsgroups: linux.kernel
Subject: Re: A mainline question about cgroup writeback
Date: Wed, 20 Apr 2016 08:40:01 +0200
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It looks like a bug on cgroup writeback. Is this a regression or
consistent issue? If it's a regression, you may could do bisect to
find out the buggy commit.

On Tue, Apr 19, 2016 at 3:19 PM, zhong jiang <zhongjiang@huawei.com> wrote:
> cgroup writeback support the filesystem both ext4 and ext2.
> but,  it appears to be not work when I test the function in the ext4.
> The example is as follows:
> echo "8:0 1048576" > blkio.throttle.write_bps_device
> echo $$ > cgroup.procs
> dd if=/dev/zero of=/test.c bs=1M count=10240
> 10240+0 records in
> 10240+0 records out
> 10737418240 bytes (11 GB) copied, 49.8796 s, 215 MB/s
>
> Furthering test find that the ratelimit will be limited if it write data
> to disk directly.  Additionly, The read ratelimit is limited whther it go through
> the page cache or not.
>
> The kernel version is 4.6  I have tested,  And the corresponding files
> in the attachment



-- 
Thanks
    Alex