From: Rik van Riel <riel@redhat.com>
To: Michel Lespinasse <walken@google.com>
Cc: Hugh Dickins <hughd@google.com>, Mel Gorman <mgorman@suse.de>,
Peter Zijlstra <peterz@infradead.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Andrea Arcangeli <aarcange@redhat.com>,
linux-mm@kvack.org
Subject: Re: [RFC PATCH 4/6] mm: vm_unmapped_area() lookup function
Date: Fri, 02 Nov 2012 20:40:48 -0400 [thread overview]
Message-ID: <50946810.7010308@redhat.com> (raw)
In-Reply-To: <CANN689Gy9izaMwrOfHi2wRcGD8Mi_x_m89YEj7qd4oyuMVCpZA@mail.gmail.com>
On 11/02/2012 06:41 PM, Michel Lespinasse wrote:
> On Fri, Nov 2, 2012 at 9:52 AM, Rik van Riel <riel@redhat.com> wrote:
>> On 10/31/2012 06:33 AM, Michel Lespinasse wrote:
> I guess the suggestion is OK in the sense that I can't see a case
> where it'd hurt. However, it still won't find all cases where we just
> unmapped a region of size N with the correct alignment - it could be
> that the first region we find has insufficient alignment, and then the
> search with an increased length could fail, even though there exists
> an aligned gap (just not the first) of the desired size. So, this is
> only a partial solution.
> Unfortunately, I don't think there is an efficient solution to the
> general problem, and the partial solutions discussed above (both yours
> and mine) don't seem to cover enough cases to warrant the complexity
> IMO...
The common case (anonymous memory) is that no alignment is
required, so your solution and mine would be equivalent :)
You are right that your solution and mine are pretty
much the same for the (rarer) cases where alignment
is needed. Lets stick with your simpler version.
ACK to your version
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next prev parent reply other threads:[~2012-11-03 0:41 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-31 10:33 [RFC PATCH 0/6] mm: use augmented rbtrees for finding unmapped areas Michel Lespinasse
2012-10-31 10:33 ` [RFC PATCH 1/6] mm: augment vma rbtree with rb_subtree_gap Michel Lespinasse
2012-11-01 21:43 ` Rik van Riel
2012-10-31 10:33 ` [RFC PATCH 2/6] mm: check rb_subtree_gap correctness Michel Lespinasse
2012-11-01 21:49 ` Rik van Riel
2012-10-31 10:33 ` [RFC PATCH 3/6] mm: rearrange vm_area_struct for fewer cache misses Michel Lespinasse
2012-10-31 10:33 ` [RFC PATCH 4/6] mm: vm_unmapped_area() lookup function Michel Lespinasse
2012-11-02 16:52 ` Rik van Riel
2012-11-02 22:41 ` Michel Lespinasse
2012-11-03 0:40 ` Rik van Riel [this message]
2012-10-31 10:33 ` [RFC PATCH 5/6] mm: use vm_unmapped_area() on x86_64 architecture Michel Lespinasse
2012-11-02 20:39 ` Rik van Riel
2012-10-31 10:33 ` [RFC PATCH 6/6] mm: fix cache coloring on x86_64 Michel Lespinasse
2012-10-31 11:03 ` [RFC PATCH 0/6] mm: use augmented rbtrees for finding unmapped areas Michel Lespinasse
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