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    x86-64: preserve large page mapping for 1st 2MB kernel txt with CONFIG_DEBUG_RODATA · b9af7c0d
    Suresh Siddha 提交于
    In the first 2MB, kernel text is co-located with kernel static
    page tables setup by head_64.S.  CONFIG_DEBUG_RODATA chops this
    2MB large page mapping to small 4KB pages as we mark the kernel text as RO,
    leaving the static page tables as RW.
    
    With CONFIG_DEBUG_RODATA disabled, OLTP run on NHM-EP shows 1% improvement
    with 2% reduction in system time and 1% improvement in iowait idle time.
    
    To recover this, move the kernel static page tables to .data section, so that
    we don't have to break the first 2MB of kernel text to small pages with
    CONFIG_DEBUG_RODATA.
    Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
    LKML-Reference: <20091014220254.063193621@sbs-t61.sc.intel.com>
    Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
    b9af7c0d
init_64.c 23.3 KB