From: "Stephen C. Tweedie" <sct@redhat.com>
To: Zlatko.Calusic@CARNet.hr
Cc: Linux-MM List <linux-mm@kvack.org>,
Linux Kernel List <linux-kernel@vger.rutgers.edu>,
Rik van Riel <H.H.vanRiel@phys.uu.nl>,
"David J. Fred" <djf@ic.net>,
"Stephen C. Tweedie" <sct@redhat.com>
Subject: Re: unexpected paging during large file reads in 2.1.127
Date: Tue, 17 Nov 1998 12:00:37 GMT [thread overview]
Message-ID: <199811171200.MAA01162@dax.scot.redhat.com> (raw)
In-Reply-To: <87lnlb5d2t.fsf@atlas.CARNet.hr>
Hi,
On 17 Nov 1998 02:21:14 +0100, Zlatko Calusic <Zlatko.Calusic@CARNet.hr>
said:
> "Stephen C. Tweedie" <sct@redhat.com> writes:
>> No, we don't. We don't evict just-read-in data, because we mark such
>> pages as PG_Referenced. It takes two complete shrink_mmap() passes
>> before we can evict such pages.
> I didn't find this in the source (in fact, add_to_page_cache clears
> PG_referenced bit, if I understood source correctly). But, see below.
You didn't understand the source correctly. :) There is an extra
bracket you missed:
page->flags = (page->flags & ~((1 << PG_uptodate) | (1 << PG_error))) | (1 << PG_referenced);
We clear PG_uptodate and PG_error, but we _set_ PG_referenced.
> I must agree entirely, because with small patch you can find below,
> performance is very very good. Thanks to marking readahead pages as
> referenced, I've been able to see exact behaviour that I wanted for a
> long time.
Excellent.
--Stephen
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next prev parent reply other threads:[~1998-11-17 12:03 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Pine.LNX.3.96.981112143712.20473B-100000@mirkwood.dummy.home>
1998-11-12 22:45 ` Zlatko Calusic
1998-11-16 19:59 ` Stephen C. Tweedie
1998-11-16 20:48 ` Rik van Riel
1998-11-16 23:05 ` Stephen C. Tweedie
1998-11-17 1:21 ` Zlatko Calusic
1998-11-17 12:00 ` Stephen C. Tweedie [this message]
1998-11-18 22:50 ` Zlatko Calusic
1998-11-17 6:42 ` Rik van Riel
1998-11-17 12:06 ` Stephen C. Tweedie
1998-11-17 20:25 ` Rik van Riel
1998-11-16 21:56 ` Zlatko Calusic
1998-11-12 23:18 ` Zlatko Calusic
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