Re: [PATCH v6 11/12] zsmalloc: page migration support

From: Minchan Kim
Date: Wed May 25 2016 - 01:14:28 EST

Hello Sergey,

On Tue, May 24, 2016 at 03:28:01PM +0900, Minchan Kim wrote:

> > hm... zsmalloc is getting sooo complex now.
> >
> > `system_wq' -- can we have problems here when the system is getting
> > low on memory and workers are getting increasingly busy trying to
> > allocate the memory for some other purposes?
> >
> > _theoretically_ zsmalloc can stack a number of ready-to-release zspages,
> > which won't be accessible to zsmalloc, nor will they be released. how likely
> > is this? hm, can zsmalloc take zspages from that deferred release list when
> > it wants to allocate a new zspage?
> Done.
> >
> > do you also want to kick the deferred page release from the shrinker
> > callback, for example?
> Yeb, it can be. I will do it at next revision. :)
> Thanks!

I tried it now but I feel strongly we want to fix shrinker first.
Now, shrinker doesn't consider VM's request(i.e., sc->nr_to_scan) but
shrink all objects which could make latency huge.

I want to fix it as another issue and then adding ZS_EMPTY pool pages
purging logic based on it because many works for zsmalloc stucked
with this patchset now which churns old code heavily. :(