From: Andrew Morton <akpm@linux-foundation.org>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: 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: Sun, 17 Feb 2013 14:54:56 -0800 [thread overview]
Message-ID: <20130217145456.375dab11.akpm@linux-foundation.org> (raw)
In-Reply-To: <87621skhtc.fsf@rustcorp.com.au>
On Sat, 16 Feb 2013 14:53:43 +1030 Rusty Russell <rusty@rustcorp.com.au> 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.
That's good news ;)
We shouldn't add it unless there's damn good reason.
> I'd really like to use it for backup programs, so they stop pulling
> random crap into memory (but leave things already resident). But that
> needs to madvise(MADV_DONTNEED) on the page, so need mmap.
>
> So why not just use mincore?
One can use fadvise(POSIX_FADV_DONTNEED) to drop the pages.
Or toss your backup app into a small memcg so it reclaims its own
stuff. See recent thread "mm: fadvise: Drain all pagevecs if
POSIX_FADV_DONTNEED fails to discard all pages"
next prev parent reply other threads:[~2013-02-17 22:56 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-11 3:13 RFC: mincore: add a bit to indicate a page is dirty Rusty Russell
2013-02-11 16:27 ` Johannes Weiner
2013-02-11 22:12 ` Andrew Morton
2013-02-12 5:44 ` Rusty Russell
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 [this message]
2013-05-29 14:53 ` Andres Freund
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
2013-02-12 5:49 ` RFC: mincore: add a bit to indicate a page is dirty Rusty Russell
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