From: Andrew Morton <akpm@osdl.org>
To: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Cc: wfg@mail.ustc.edu.cn, linux-kernel@vger.kernel.org,
christoph@lameter.com, riel@redhat.com, a.p.zijlstra@chello.nl,
npiggin@suse.de, andrea@suse.de, magnus.damm@gmail.com
Subject: Re: [PATCH 02/12] mm: supporting variables and functions for balanced zone aging
Date: Thu, 1 Dec 2005 15:03:49 -0800 [thread overview]
Message-ID: <20051201150349.3538638e.akpm@osdl.org> (raw)
In-Reply-To: <20051201222846.GA3646@dmt.cnet>
Marcelo Tosatti <marcelo.tosatti@cyclades.com> wrote:
>
> Hi Andrew,
>
> On Thu, Dec 01, 2005 at 02:37:14AM -0800, Andrew Morton wrote:
> > Wu Fengguang <wfg@mail.ustc.edu.cn> wrote:
> > >
> > > The zone aging rates are currently imbalanced,
> >
> > ZONE_DMA is out of whack. It shouldn't be, and I'm not aware of anyone
> > getting in and working out why. I certainly wouldn't want to go and add
> > all this stuff without having a good understanding of _why_ it's out of
> > whack. Perhaps it's just some silly bug, like the thing I pointed at in
> > the previous email.
>
> I think that the problem is caused by the interaction between
> the way reclaiming is quantified and parallel allocators.
Could be. But what about the bug which I think is there? That'll cause
overscanning of the DMA zone.
> The zones have different sizes, and each zone reclaim iteration
> scans the same number of pages. It is unfair.
Nope. See how shrink_zone() bases nr_active and nr_inactive on
zone->nr_active and zone_nr_inactive. These calculations are intended to
cause the number of scanned pages in each zone to be
(zone->nr-active + zone->nr_inactive) >> sc->priority.
> On top of that, kswapd is likely to block while doing its job,
> which means that allocators have a chance to run.
kswapd should only block under rare circumstances - huge amounts of dirty
pages coming off the tail of the LRU.
> --- mm/vmscan.c.orig 2006-01-01 12:44:39.000000000 -0200
> +++ mm/vmscan.c 2006-01-01 16:43:54.000000000 -0200
> @@ -616,8 +616,12 @@
> {
Please use `diff -p'.
next prev parent reply other threads:[~2005-12-01 23:04 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-01 10:18 [PATCH 00/12] Balancing the scan rate of major caches Wu Fengguang
2005-12-01 10:18 ` [PATCH 01/12] vm: kswapd incmin Wu Fengguang
2005-12-01 10:33 ` Andrew Morton
2005-12-01 11:40 ` Wu Fengguang
2005-12-01 10:18 ` [PATCH 02/12] mm: supporting variables and functions for balanced zone aging Wu Fengguang
2005-12-01 10:37 ` Andrew Morton
2005-12-01 12:11 ` Wu Fengguang
2005-12-01 22:28 ` Marcelo Tosatti
2005-12-01 23:03 ` Andrew Morton [this message]
2005-12-02 1:19 ` Wu Fengguang
2005-12-02 1:30 ` Andrew Morton
2005-12-02 2:04 ` Wu Fengguang
2005-12-02 2:18 ` Andrea Arcangeli
2005-12-02 2:37 ` Wu Fengguang
2005-12-02 2:52 ` Andrea Arcangeli
2005-12-02 4:45 ` Andrew Morton
2005-12-02 6:38 ` Wu Fengguang
2005-12-02 2:27 ` Nick Piggin
2005-12-02 2:36 ` Andrea Arcangeli
2005-12-02 2:43 ` Wu Fengguang
2005-12-02 5:49 ` Andrew Morton
2005-12-02 7:18 ` Wu Fengguang
2005-12-02 7:27 ` Andrew Morton
2005-12-02 15:13 ` Marcelo Tosatti
2005-12-02 21:39 ` Andrew Morton
2005-12-03 0:26 ` Marcelo Tosatti
2005-12-04 6:06 ` Wu Fengguang
2005-12-02 1:26 ` Marcelo Tosatti
2005-12-02 3:40 ` Andrew Morton
2005-12-01 10:18 ` [PATCH 03/12] mm: balance zone aging in direct reclaim path Wu Fengguang
2005-12-01 10:18 ` [PATCH 04/12] mm: balance zone aging in kswapd " Wu Fengguang
2005-12-01 10:18 ` [PATCH 05/12] mm: balance slab aging Wu Fengguang
2005-12-01 10:18 ` [PATCH 06/12] mm: balance active/inactive list scan rates Wu Fengguang
2005-12-01 11:39 ` Peter Zijlstra
2005-12-01 10:18 ` [PATCH 07/12] mm: remove unnecessary variable and loop Wu Fengguang
2005-12-01 10:18 ` [PATCH 08/12] mm: remove swap_cluster_max from scan_control Wu Fengguang
2005-12-01 10:18 ` [PATCH 09/12] mm: accumulate sc.nr_scanned/sc.nr_reclaimed Wu Fengguang
2005-12-01 10:18 ` [PATCH 10/12] mm: merge sc.may_writepage and sc.may_swap into sc.flags Wu Fengguang
2005-12-01 10:18 ` [PATCH 11/12] mm: add page reclaim debug traces Wu Fengguang
2005-12-01 10:18 ` [PATCH 12/12] mm: fix minor scan count bugs Wu Fengguang
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