linux-kernel - Re: [PATCHv4 17/17] writeback: lessen sync

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Date:	Thu, 27 May 2010 13:19:03 +0300
From:	Artem Bityutskiy <dedekind1@...il.com>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Jens Axboe <jens.axboe@...cle.com>,
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCHv4 17/17] writeback: lessen sync_supers wakeup count

On Thu, 2010-05-27 at 07:50 +0100, Al Viro wrote:
> On Tue, May 25, 2010 at 04:49:12PM +0300, Artem Bityutskiy wrote:
> > From: Artem Bityutskiy <Artem.Bityutskiy@...ia.com>
> > +void mark_sb_dirty(struct super_block *sb)
> > +{
> > +	sb->s_dirty = 1;
> > +
> > +	spin_lock(&supers_timer_lock);
> > +	if (!supers_timer_armed) {
> > +		bdi_arm_supers_timer();
> > +		supers_timer_armed = 1;
> > +	} else if (supers_timer_armed == -1)
> > +		supers_timer_armed = 1;
> > +	spin_unlock(&supers_timer_lock);
> > +}
> > +EXPORT_SYMBOL(mark_sb_dirty);
> 
> Ouch...   That turns a previously trivial operation into something
> much heavier; moreover, I'd rather see serious review of s_dirt
> uses.

OK, I'll try to do something lighter with atomic variables or something
like Nick posted - need to think about this. And I'll try to review
s_dirty usage as much as my time and knowledge allow. Thanks.

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)

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