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    SubjectRe: [PATCH] lazy freeing of memory through MADV_FREE
    On Tue, 17 Apr 2007 03:15:51 -0400 Rik van Riel <> wrote:

    > Make it possible for applications to have the kernel free memory
    > lazily. This reduces a repeated free/malloc cycle from freeing
    > pages and allocating them, to just marking them freeable. If the
    > application wants to reuse them before the kernel needs the memory,
    > not even a page fault will happen.
    > This patch, together with Ulrich's glibc change, increases
    > MySQL sysbench performance by a factor of 2 on my quad core
    > test system.

    In file included from include/linux/mman.h:4,
    from arch/sparc64/kernel/sys_sparc.c:19:
    include/asm/mman.h:36:1: "MADV_FREE" redefined
    In file included from include/asm/mman.h:5,
    from include/linux/mman.h:4,
    from arch/sparc64/kernel/sys_sparc.c:19:
    include/asm-generic/mman.h:32:1: this is the location of the previous definition

    sparc32 and sparc64 already defined MADV_FREE:

    #define MADV_FREE 0x5 /* (Solaris) contents can be freed */

    I'll remove the sparc definitions for now, but we need to work out what
    we're going to do here. Your patch changes the values of MADV_FREE on

    Perhaps this should be renamed to MADV_FREE_LINUX and given a different
    number. It depends on how close your proposed behaviour is to Solaris's.

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      Last update: 2007-04-22 10:21    [W:0.025 / U:6.732 seconds]
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