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| author | Suresh Siddha <suresh.b.siddha@intel.com> | 2009-10-14 14:46:55 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2009-10-20 14:46:00 +0900 |
| commit | b9af7c0d44b8bb71e3af5e94688d076414aa8c87 (patch) | |
| tree | 8f61c3cf73224a5c698da853b42b17579b824c0b /arch/x86/kernel/head_64.S | |
| parent | adc1938994f7f1112d335d998b5218b0aa680ad6 (diff) | |
| download | talos-obmc-linux-b9af7c0d44b8bb71e3af5e94688d076414aa8c87.tar.gz talos-obmc-linux-b9af7c0d44b8bb71e3af5e94688d076414aa8c87.zip | |
x86-64: preserve large page mapping for 1st 2MB kernel txt with CONFIG_DEBUG_RODATA
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: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <20091014220254.063193621@sbs-t61.sc.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'arch/x86/kernel/head_64.S')
| -rw-r--r-- | arch/x86/kernel/head_64.S | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 780cd928fcd5..b55ee4ff509f 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -262,11 +262,11 @@ ENTRY(secondary_startup_64) .quad x86_64_start_kernel ENTRY(initial_gs) .quad INIT_PER_CPU_VAR(irq_stack_union) - __FINITDATA ENTRY(stack_start) .quad init_thread_union+THREAD_SIZE-8 .word 0 + __FINITDATA bad_address: jmp bad_address @@ -340,6 +340,7 @@ ENTRY(name) i = i + 1 ; \ .endr + .data /* * This default setting generates an ident mapping at address 0x100000 * and a mapping for the kernel that precisely maps virtual address |
