From: Rik van Riel <riel@redhat.com>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Mel Gorman <mel@csn.ul.ie>, Johannes Weiner <hannes@cmpxchg.org>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
hughd@google.com
Subject: Re: [PATCH -mm 2/2] mm: do not reset mm->free_area_cache on every single munmap
Date: Tue, 20 Mar 2012 15:06:03 -0400 [thread overview]
Message-ID: <4F68D51B.7030501@redhat.com> (raw)
In-Reply-To: <20120320190055.GZ24602@redhat.com>
On 03/20/2012 03:00 PM, Andrea Arcangeli wrote:
> On Thu, Feb 23, 2012 at 01:56:14PM -0800, Andrew Morton wrote:
>> We've been playing whack-a-mole with this search for many years. What
>> about developing a proper data structure with which to locate a
>> suitable-sized hole in O(log(N)) time?
>
> I intended to implement it a couple of years ago.
>
> It takes a change to the rbtree code so that when rb_erase and
> rb_insert_color are called, proper methods are called to notify the
> caller that there's been a rotation (probably calling a new
> rb_insert_color_with_metadata(&method(left_rot, right_rot)) )
There are two issues here.
1) We also need the ability to search by address, so we can
merge free areas that are adjacent.
2) Hugetlb, shared mappings on architectures with virtually
indexed caches (eg. MIPS) need holes that are not only of
a certain size, but also fit a certain alignment.
To get (2) we are essentially back to tree walking. I am not
convinced that that is a lot better than what we are doing
today, or worth the extra complexity...
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next prev parent reply other threads:[~2012-03-20 19:06 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-23 19:54 [PATCH -mm 0/2] speed up arch_get_unmapped_area Rik van Riel
2012-02-23 19:56 ` [PATCH -mm 1/2] mm: fix quadratic behaviour in get_unmapped_area_topdown Rik van Riel
2012-02-23 21:50 ` Andrew Morton
2012-02-23 21:57 ` Johannes Weiner
2012-02-23 20:00 ` [PATCH -mm 2/2] mm: do not reset mm->free_area_cache on every single munmap Rik van Riel
2012-02-23 21:56 ` Andrew Morton
2012-02-27 16:12 ` Rik van Riel
2012-03-20 18:32 ` Rik van Riel
2012-03-20 19:00 ` Andrea Arcangeli
2012-03-20 19:06 ` Rik van Riel [this message]
2012-02-23 21:57 ` Andi Kleen
2012-02-27 16:13 ` Rik van Riel
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