linux-kernel - A mainline question about cgroup writeback

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Message-ID: <5715DC1F.2020803@huawei.com>
Date:	Tue, 19 Apr 2016 15:19:59 +0800
From:	zhong jiang <zhongjiang@...wei.com>
To:	<tj@...nel.org>
CC:	Miao Xie <miaoxie@...wei.com>, <lizefan@...wei.com>,
	<dingxiang@...wei.com>, LKML <linux-kernel@...r.kernel.org>
Subject: A mainline question about cgroup writeback

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

View attachment "euler_defconfig" of type "text/plain" (138077 bytes)