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    Subject[patch] x86: Fix incorrect __read_mostly on _boot_cpu_pda
    The pda rework (commit 3461b0af025251bbc6b3d56c821c6ac2de6f7209)
    to remove static boot cpu pdas introduced a bug. _boot_cpu_pda is the
    actual pda used by the boot cpu and is definitely not "__read_mostly" and
    ended up polluting the read mostly section with writes. This bug caused
    regression of about 8-10% on certain syscall intensive workloads.

    Signed-off-by: Ravikiran Thirumalai <>

    Index: linux-2.6/arch/x86/kernel/head64.c
    --- linux-2.6.orig/arch/x86/kernel/head64.c 2008-12-30 15:28:08.000000000 -0800
    +++ linux-2.6/arch/x86/kernel/head64.c 2008-12-31 10:36:21.000000000 -0800
    @@ -27,7 +27,7 @@
    #include <asm/trampoline.h>

    /* boot cpu pda */
    -static struct x8664_pda _boot_cpu_pda __read_mostly;
    +static struct x8664_pda _boot_cpu_pda;

    #ifdef CONFIG_SMP

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      Last update: 2008-12-31 23:25    [W:0.019 / U:3.080 seconds]
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