From: Dave Chinner <david@fromorbit.com>
To: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: remove struct reclaim_state
Date: Sat, 19 Nov 2011 08:09:41 +1100 [thread overview]
Message-ID: <20111118210941.GK7046@dastard> (raw)
In-Reply-To: <4EC62E46.6080503@openvz.org>
On Fri, Nov 18, 2011 at 02:07:02PM +0400, Konstantin Khlebnikov wrote:
> Dave Chinner wrote:
> >On Fri, Nov 18, 2011 at 01:28:06PM +0300, Konstantin Khlebnikov wrote:
> >>Memory reclaimer want to know how much pages was reclaimed during shrinking slabs.
> >>Currently there is special struct reclaim_state with single counter and pointer from
> >>task-struct. Let's store counter direcly on task struct and account freed pages
> >>unconditionally. This will reduce stack usage and simplify code in reclaimer and slab.
> >>
> >>Logic in do_try_to_free_pages() is slightly changed, but this is ok.
> >>Nobody calls shrink_slab() explicitly before do_try_to_free_pages(),
> >
> >Except for drop_slab() and shake_page()....
>
> Indeed, but they do not care about accounting reclaimed pages and
> they do not call do_try_to_free_pages() after all.
Right, so you're effectively leaving a landmine for someone to trip
over - anyone that cares about accounting during shrink_slab needs
to zero the value first. The current code makes this obvious by not
having a reclaim structure in the cases where callers don't care
about accounting - after your change the correct usage is
undocumented....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2011-11-18 21:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-18 10:28 [PATCH] mm: remove struct reclaim_state Konstantin Khlebnikov
2011-11-18 9:56 ` Dave Chinner
2011-11-18 10:07 ` Konstantin Khlebnikov
2011-11-18 21:09 ` Dave Chinner [this message]
2011-11-19 9:55 ` [PATCH v2] " Konstantin Khlebnikov
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