From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Huang Shijie <shijie8@gmail.com>
Cc: Minchan Kim <minchan.kim@gmail.com>,
akpm@linux-foundation.org, mel@csn.ul.ie,
kosaki.motohiro@jp.fujitsu.com, linux-mm@kvack.org,
Rik van Riel <riel@redhat.com>,
Wu Fengguang <fengguang.wu@intel.com>
Subject: Re: [PATCH 4/4] mm/page_alloc : relieve zone->lock's pressure for memory free
Date: Tue, 12 Jan 2010 11:07:40 +0900 [thread overview]
Message-ID: <20100112110740.54813cf6.kamezawa.hiroyu@jp.fujitsu.com> (raw)
In-Reply-To: <4B4BD849.7050007@gmail.com>
On Tue, 12 Jan 2010 10:02:49 +0800
Huang Shijie <shijie8@gmail.com> wrote:
>
> >> Thanks, Huang.
> >>
> >> Frankly speaking, I am not sure this ir right way.
> >> This patch is adding to fine-grained locking overhead
> >>
> >> As you know, this functions are one of hot pathes.
> >> In addition, we didn't see the any problem, until now.
> >> It means out of synchronization in ZONE_ALL_UNRECLAIMABLE
> >> and pages_scanned are all right?
> >>
> >> If it is, we can move them out of zone->lock, too.
> >> If it isn't, we need one more lock, then.
> >>
> >>
> > I don't want to see additional spin_lock, here.
> >
> I don't want it either.
> > About ZONE_ALL_UNRECLAIMABLE, it's not necessary to be handled in atomic way.
> > If you have concerns with other flags, please modify this with single word,
> > instead of a bit field.
> >
> >
> How about the `pages_scanned' ?
> It's protected by the zone->lru_lock in shrink_{in}active_list().
>
Zero-clear by page-scanned is done by a write (atomic). Then, possible race
will be this update,
zone->pages_scanend += scanned;
And failing to reset the number. But, IMHO, failure to reset this counter
is not a big problem. We'll finally reset this when we free the next
page. So, I have no concerns about resetting this counter.
My only concern is race with other flags.
Thanks,
-Kame
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next prev parent reply other threads:[~2010-01-12 2:10 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-11 4:37 [PATCH 1/4] mm/page_alloc : rename rmqueue_bulk to rmqueue_single Huang Shijie
2010-01-11 4:37 ` [PATCH 2/4] mm/page_alloc : relieve the zone->lock's pressure for allocation Huang Shijie
2010-01-11 4:37 ` [PATCH 3/4] mm/page_alloc : modify the return type of __free_one_page Huang Shijie
2010-01-11 4:37 ` [PATCH 4/4] mm/page_alloc : relieve zone->lock's pressure for memory free Huang Shijie
2010-01-11 5:20 ` Minchan Kim
2010-01-11 6:01 ` Huang Shijie
2010-01-11 6:27 ` Huang Shijie
2010-01-11 6:38 ` Minchan Kim
2010-01-11 6:59 ` Huang Shijie
2010-01-12 0:47 ` KAMEZAWA Hiroyuki
2010-01-12 2:02 ` Huang Shijie
2010-01-12 2:07 ` KAMEZAWA Hiroyuki [this message]
2010-01-12 2:32 ` Huang Shijie
2010-01-12 2:27 ` Wu Fengguang
2010-01-12 2:56 ` KOSAKI Motohiro
2010-01-12 3:02 ` Huang Shijie
2010-01-12 4:05 ` Minchan Kim
2010-01-12 4:21 ` Wu Fengguang
2010-01-12 4:32 ` KAMEZAWA Hiroyuki
2010-01-12 4:59 ` Wu Fengguang
2010-01-12 5:09 ` Wu Fengguang
2010-01-12 5:10 ` KOSAKI Motohiro
2010-01-12 7:36 ` David Rientjes
2010-01-12 8:56 ` KOSAKI Motohiro
2010-01-12 21:39 ` David Rientjes
2010-01-13 0:01 ` KOSAKI Motohiro
2010-01-12 4:48 ` Minchan Kim
2010-01-12 2:51 ` Huang Shijie
2010-01-12 3:03 ` Wu Fengguang
2010-01-12 3:05 ` KOSAKI Motohiro
2010-01-11 5:04 ` [PATCH 3/4] mm/page_alloc : modify the return type of __free_one_page Minchan Kim
2010-01-12 2:56 ` KOSAKI Motohiro
2010-01-18 11:25 ` Mel Gorman
2010-01-19 1:49 ` Huang Shijie
2010-01-11 5:02 ` [PATCH 2/4] mm/page_alloc : relieve the zone->lock's pressure for allocation Minchan Kim
2010-01-11 5:13 ` Huang Shijie
2010-01-12 2:54 ` KOSAKI Motohiro
2010-01-18 11:24 ` Mel Gorman
2010-01-11 5:00 ` [PATCH 1/4] mm/page_alloc : rename rmqueue_bulk to rmqueue_single Minchan Kim
2010-01-12 2:52 ` KOSAKI Motohiro
2010-01-18 11:21 ` Mel Gorman
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