linux-kernel - Re: A mainline question about cgroup writeback

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Message-ID: <20160420212251.GF4775@htj.duckdns.org>
Date:	Wed, 20 Apr 2016 17:22:51 -0400
From:	Tejun Heo <tj@...nel.org>
To:	zhong jiang <zhongjiang@...wei.com>
Cc:	Miao Xie <miaoxie@...wei.com>, lizefan@...wei.com,
	dingxiang@...wei.com, LKML <linux-kernel@...r.kernel.org>
Subject: Re: A mainline question about cgroup writeback

On Tue, Apr 19, 2016 at 03:19:59PM +0800, zhong jiang 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

How much memory does the cgroup have available to it?  It's buffered
write.  It might not get throttled if there are enough pages to dirty.

Thanks.

-- 
tejun