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Date: Wed, 5 Dec 2001 17:38:52 +0300
From: Peter Zaitsev <pz@spylog.ru>
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To: Andrea Arcangeli <andrea@suse.de>
Cc: Rik van Riel <riel@conectiva.com.br>, Andrew Morton <akpm@zip.com.au>,
        theowl@freemail.c3.hu, <theowl@freemail.hu>,
        <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@transmeta.com>
Subject: Re[2]: your mail on mmap() to the kernel list
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Hello Andrea,

>>
>> OTOH, I doubt it would help real-world workloads where the
>> application maps and unmaps areas of different sizes and
>> actually does something with the memory instead of just
>> mapping and unmapping it ;)))

AA> exactly, while that would be simple to implement and very lightweight at
AA> runtime, that's not enough to mathematically drop the complexity of the
AA> get_unmapped_area algorithm. It would optimize only the case where
AA> there's no fragmentation of the mapped virtual address space.

And also will optimize all mappings of 4K and (which are at least 70%
in mu case) :)

AA> For finding the best fit in the heap with O(log(N)) complexity (rather
AA> than the current O(N) complexity of the linked list) one tree indexed by
AA> the size of each hole would be necessary.

This of course would be the best way.


-- 
Best regards,
 Peter                            mailto:pz@spylog.ru

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