From: Andrea Arcangeli <aarcange@redhat.com>
To: Izik Eidus <ieidus@redhat.com>
Cc: Robin Holt <holt@sgi.com>,
Hugh Dickins <hugh.dickins@tiscali.co.uk>,
Chris Wright <chrisw@redhat.com>,
linux-mm@kvack.org
Subject: Re: [Patch] mm/ksm.c is doing an unneeded _notify in write_protect_page.
Date: Thu, 11 Mar 2010 17:06:16 +0100 [thread overview]
Message-ID: <20100311160616.GH5677@random.random> (raw)
In-Reply-To: <20100311180159.124ffecd@redhat.com>
On Thu, Mar 11, 2010 at 06:01:59PM +0200, Izik Eidus wrote:
> On Thu, 11 Mar 2010 09:54:22 -0600
> Robin Holt <holt@sgi.com> wrote:
>
> >
> > ksm.c's write_protect_page implements a lockless means of verifying a
> > page does not have any users of the page which are not accounted for via
> > other kernel tracking means. It does this by removing the writable pte
> > with TLB flushes, checking the page_count against the total known users,
> > and then using set_pte_at_notify to make it a read-only entry.
> >
> > An unneeded mmu_notifier callout is made in the case where the known
> > users does not match the page_count. In that event, we are inserting
> > the identical pte and there is no need for the set_pte_at_notify, but
> > rather the simpler set_pte_at suffices.
> >
> > Signed-off-by: Robin Holt <holt@sgi.com>
> > To: Izik Eidus <ieidus@redhat.com>
> > Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
> > Cc: Chris Wright <chrisw@redhat.com>
> > Cc: linux-mm@kvack.org
>
> Acked-by: Izik Eidus <ieidus@redhat.com>
Ack too. I misunderstood what you were talking about before, patch
makes it clear now ;).
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next prev parent reply other threads:[~2010-03-11 16:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-10 19:18 mm/ksm.c seems to be doing an unneeded _notify Robin Holt
2010-03-10 20:19 ` Chris Wright
2010-03-10 20:19 ` Izik Eidus
2010-03-10 22:19 ` Andrea Arcangeli
2010-03-11 6:23 ` Hugh Dickins
2010-03-11 13:20 ` Izik Eidus
2010-03-11 15:54 ` [Patch] mm/ksm.c is doing an unneeded _notify in write_protect_page Robin Holt
2010-03-11 16:01 ` Izik Eidus
2010-03-11 16:06 ` Andrea Arcangeli [this message]
-- strict thread matches above, loose matches on Subject: below --
2010-03-11 17:23 Robin Holt
2010-03-11 18:44 ` Hugh Dickins
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