Re: [PATCH] mm/vmstat: Reduce zone lock hold time when reading /proc/pagetypeinfo

From: Feng Tang
Date: Thu Oct 24 2019 - 21:38:07 EST

On Thu, Oct 24, 2019 at 06:51:54PM +0800, Qian Cai wrote:
> > On Oct 24, 2019, at 1:34 AM, Feng Tang <feng.tang@xxxxxxxxx> wrote:
> >
> > One example is, there was a platform with limited DRAM, so it preset
> > some CMA memory for camera's big buffer allocation use, while it let
> > these memory to be shared by others when camera was not used. And
> > after long time running, the cma region got fragmented and camera
> > app started to fail due to the buffer allocation failure. And during
> > debugging, we kept monitoring the buddy info for different migrate
> > types.
> For CMA-specific debugging, why CMA debugfs is not enough?

We care about change flow of the numbers of different orders for cma
and other migrate types, sometimes I just use one simple cmd
watch -d 'cat /proc/pagetypeinfo'
which shows direct and dynamic flows.