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From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	akpm@linux-foundation.org, sergey.senozhatsky@gmail.com,
	ngupta@vflare.org, sfr@canb.auug.org.au,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [withdrawn] zsmalloc-remove-extra-cond_resched-in-__zs_compact.patch removed from -mm tree
Date: Thu, 26 Mar 2015 17:13:13 +0900	[thread overview]
Message-ID: <20150326081313.GB1669@swordfish> (raw)
In-Reply-To: <20150326073916.GB26725@blaptop>

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

WARNING: multiple messages have this Message-ID (diff)
From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	akpm@linux-foundation.org, sergey.senozhatsky@gmail.com,
	ngupta@vflare.org, sfr@canb.auug.org.au,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [withdrawn] zsmalloc-remove-extra-cond_resched-in-__zs_compact.patch removed from -mm tree
Date: Thu, 26 Mar 2015 17:13:13 +0900	[thread overview]
Message-ID: <20150326081313.GB1669@swordfish> (raw)
In-Reply-To: <20150326073916.GB26725@blaptop>

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

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  reply	other threads:[~2015-03-26  8:13 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-25 20:25 [withdrawn] zsmalloc-remove-extra-cond_resched-in-__zs_compact.patch removed from -mm tree akpm
2015-03-26  0:27 ` Sergey Senozhatsky
2015-03-26  0:27   ` Sergey Senozhatsky
2015-03-26  7:39   ` Minchan Kim
2015-03-26  7:39     ` Minchan Kim
2015-03-26  8:13     ` Sergey Senozhatsky [this message]
2015-03-26  8:13       ` Sergey Senozhatsky
2015-03-27  2:34       ` Minchan Kim
2015-03-27  2:34         ` Minchan Kim

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