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    Subject[14/45] x86, kdump: Change copy_oldmem_page() to use cached addressing
    2.6.32-stable review patch.  If anyone has any objections, please let us know.


    From: Cliff Wickman <>

    commit 37a2f9f30a360fb03522d15c85c78265ccd80287 upstream.

    The copy of /proc/vmcore to a user buffer proceeds much faster
    if the kernel addresses memory as cached.

    With this patch we have seen an increase in transfer rate from
    less than 15MB/s to 80-460MB/s, depending on size of the
    transfer. This makes a big difference in time needed to save a
    system dump.

    Signed-off-by: Cliff Wickman <>
    Acked-by: "Eric W. Biederman" <>
    LKML-Reference: <>
    Signed-off-by: Ingo Molnar <>
    Signed-off-by: Greg Kroah-Hartman <>

    arch/x86/kernel/crash_dump_64.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/arch/x86/kernel/crash_dump_64.c
    +++ b/arch/x86/kernel/crash_dump_64.c
    @@ -34,7 +34,7 @@ ssize_t copy_oldmem_page(unsigned long p
    if (!csize)
    return 0;

    - vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
    + vaddr = ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE);
    if (!vaddr)
    return -ENOMEM;

     \ /
      Last update: 2010-11-19 22:57    [W:0.041 / U:1.780 seconds]
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