Re: [withdrawn] zsmalloc-remove-extra-cond_resched-in-__zs_compact.patch removed from -mm tree

Sergey Senozhatsky
2015-03-26T08:13:06Z

On (03/26/15 16:39), Minchan Kim wrote:
> Hello Sergey,
>
> Sorry for slow response.
> I am overwhelmed with too much to do. :(
>

Hello,
sure, no problem.

> > > diff -puN mm/zsmalloc.c~zsmalloc-remove-extra-cond_resched-in-__zs_compact mm/zsmalloc.c
> > > --- a/mm/zsmalloc.c~zsmalloc-remove-extra-cond_resched-in-__zs_compact
> > > +++ a/mm/zsmalloc.c
> > > @@ -1717,8 +1717,6 @@ static unsigned long __zs_compact(struct
> > > struct page *dst_page = NULL;
> > > unsigned long nr_total_migrated = 0;
> > >
> > > - cond_resched();
> > > -
> > > spin_lock(&class->lock);
> > > while ((src_page = isolate_source_page(class))) {

>
> If we removed cond_resched out of outer loop(ie, your patch), we lose
> the chance to reschedule if alloc_target_page fails(ie, there is no
> zspage in ZS_ALMOST_FULL and ZS_ALMOST_EMPTY).

in outer loop we have preemption enabled and unlocked class. wouldn't that help?
(hm, UP system?)

> It might be not rare event if we does compation successfully for a
> size_class. However, with next coming higher size_class for __zs_compact,
> we will encounter cond_resched during compaction.
> So, I am happy to ack. :)
>
> Acked-by: Minchan Kim <minchan@kernel.org>

thanks!

-ss