From: Andres Freund <andres@2ndquadrant.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
LKML <linux-kernel@vger.kernel.org>,
Nick Piggin <npiggin@suse.de>,
Stewart Smith <stewart@flamingspork.com>,
linux-mm@kvack.org, linux-arch@vger.kernel.org
Subject: Re: [patch 1/2] mm: fincore()
Date: Wed, 29 May 2013 16:53:12 +0200 [thread overview]
Message-ID: <20130529145312.GE3955@alap2.anarazel.de> (raw)
In-Reply-To: <87621skhtc.fsf@rustcorp.com.au>
On 2013-02-16 14:53:43 +1030, Rusty Russell wrote:
> Andrew Morton <akpm@linux-foundation.org> writes:
> > On Fri, 15 Feb 2013 18:13:04 -0500
> > Johannes Weiner <hannes@cmpxchg.org> wrote:
> >> I dunno. The byte vector might not be optimal but its worst cases
> >> seem more attractive, is just as extensible, and dead simple to use.
> >
> > But I think "which pages from this 4TB file are in core" will not be an
> > uncommon usage, and writing a gig of memory to find three pages is just
> > awful.
>
> Actually, I don't know of any usage for this call.
[months later, catching up]
I do. Postgres' could really use something like that for making saner
assumptions about the cost of doing an index/heap scan. postgres doesn't
use mmap() and mmaping larger files into memory isn't all that cheap
(32bit...) so having fincore would be nice.
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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next prev parent reply other threads:[~2013-05-29 14:53 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <87a9rbh7b4.fsf@rustcorp.com.au>
[not found] ` <20130211162701.GB13218@cmpxchg.org>
[not found] ` <20130211141239.f4decf03.akpm@linux-foundation.org>
2013-02-15 6:34 ` [patch 1/2] mm: fincore() Johannes Weiner
2013-02-15 20:39 ` David Miller
2013-02-15 21:14 ` Andrew Morton
2013-02-15 22:28 ` Johannes Weiner
2013-02-15 22:34 ` Andrew Morton
2013-02-15 21:27 ` Andrew Morton
2013-02-15 23:13 ` Johannes Weiner
2013-02-15 23:42 ` Andrew Morton
2013-02-16 4:23 ` Rusty Russell
2013-02-17 22:51 ` Johannes Weiner
2013-02-17 22:54 ` Andrew Morton
2013-05-29 14:53 ` Andres Freund [this message]
2013-05-29 17:32 ` Johannes Weiner
2013-05-29 17:52 ` Andres Freund
2013-02-18 5:41 ` Rusty Russell
2013-02-19 10:25 ` Simon Jeons
2013-02-15 6:35 ` [patch 2/2] x86-64: hook up fincore() syscall Johannes Weiner
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