From: Nikita Danilov <Nikita@Namesys.COM>
To: Nick Piggin <piggin@cyberone.com.au>
Cc: Andrew Morton <akpm@osdl.org>, linux-mm@kvack.org
Subject: Re: [BENCHMARKS] Namesys VM patches improve kbuild
Date: Mon, 26 Jan 2004 14:19:50 +0300 [thread overview]
Message-ID: <16404.63446.649110.348477@laputa.namesys.com> (raw)
In-Reply-To: <4011C537.8040104@cyberone.com.au>
Nick Piggin writes:
>
[...]
>
> But by clearing the referenced bit when below the reclaim_mapped
> threshold, you're throwing this information away.
>
> Say you have 16 mapped pages on the active list, 8 referenced, 8 not.
> You do a !reclaim_mapped scan. Your 16 pages are now in the same
> order and none are referenced. You now do a reclaim_mapped scan and
> reclaim 8 pages. 4 of them were the referenced ones, 4 were not.
>
> With my change, you would reclaim all 8 non referenced pages.
Which is wrong, because none of them was referenced _recently_. These
pages are cold, according to the VM's notion of hotness. (Long time
probably has passed between !reclaim_mapped and reclaim_mapped scans in
your example.)
It seems correct to make deactivation decision on the basic of recent
accesses to the page rather than by checking whether page was ever
accessed.
>
Nikita.
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next prev parent reply other threads:[~2004-01-26 11:19 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-22 5:43 Nick Piggin
2004-01-22 6:36 ` Andrew Morton
2004-01-22 6:54 ` Nick Piggin
2004-01-22 7:04 ` Andrew Morton
2004-01-22 7:19 ` Nick Piggin
2004-01-22 8:16 ` William Lee Irwin III
2004-01-22 23:32 ` Nick Piggin
2004-01-22 10:35 ` Nikita Danilov
2004-01-22 23:01 ` Nick Piggin
2004-01-23 10:29 ` Nikita Danilov
2004-01-23 12:28 ` Nick Piggin
2004-01-23 15:09 ` Nick Piggin
2004-01-23 15:40 ` Nikita Danilov
2004-01-24 1:07 ` Nick Piggin
2004-01-26 11:19 ` Nikita Danilov [this message]
2004-01-26 11:25 ` Nick Piggin
2004-01-26 12:14 ` Nikita Danilov
2004-01-30 3:48 ` Nick Piggin
2004-01-30 3:56 ` Andrew Morton
2004-01-30 12:00 ` Nikita Danilov
2004-01-23 7:16 ` Nick Piggin
2004-01-23 9:42 ` Nikita Danilov
2004-01-23 12:15 ` Nick Piggin
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