Re: [BUG]Writeback Cgroup/Dirty Throttle: very small buffered write thoughput caused by writeback cgroup and dirty thottle

From: Tejun Heo
Date: Fri May 27 2016 - 14:24:16 EST


Sorry about the delay. I forgot about this thread.

On Fri, May 13, 2016 at 02:11:53PM +0800, Miao Xie wrote:
> Better than the kernel without patch. Now the benchmark could reach
> the device bandwidth after 5-8 seconds. But at the beginning, it
> was still very slow, and its thoughput was only 4MB/s for ~4
> seconds, then it could go up in 1~3 seconds.

I see. As this fix is needed anyways, I'll send it up. As for the
ramp-up, it could be normal. There are estimators which take running
avg and modulate the threshold accordingly and the starting values are
conservative, so a short ramp-up time can be coming from that.