Re: [PATCH 3/3] x86: add local_tlb_flush_kernel_range()
From: Minchan Kim <minchan@kernel.org>
Date: 2012-06-27 05:53:26
Also in:
lkml
On 06/26/2012 01:14 AM, Seth Jennings wrote:
This patch adds support for a local_tlb_flush_kernel_range() function for the x86 arch. This function allows for CPU-local TLB flushing, potentially using invlpg for single entry flushing, using an arch independent function name. Signed-off-by: Seth Jennings <redacted>
Anyway, we don't matter INVLPG_BREAK_EVEN_PAGES's optimization point is 8 or something. We do care only it works without big problem. I believe after Alex's patch is settle down, we can fix it if it's wrong. But it shouldn't prevent merging this patch. Acked-by: Minchan Kim <minchan@kernel.org> Nitpick: I expect you change __HAVE_LOCAL_XXX to __HAVE_ARCH_LOCAL_XXX in next spin. :)
quoted hunk ↗ jump to hunk
--- arch/x86/include/asm/tlbflush.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 36a1a2a..92a280b 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h@@ -168,4 +168,25 @@ static inline void flush_tlb_kernel_range(unsigned long start, flush_tlb_all(); } +#define __HAVE_LOCAL_FLUSH_TLB_KERNEL_RANGE +/* + * INVLPG_BREAK_EVEN_PAGES is the number of pages after which single tlb + * flushing becomes more costly than just doing a complete tlb flush. + * While this break even point varies among x86 hardware, tests have shown + * that 8 is a good generic value. +*/ +#define INVLPG_BREAK_EVEN_PAGES 8 +static inline void local_flush_tlb_kernel_range(unsigned long start, + unsigned long end) +{ + if (cpu_has_invlpg && + (end - start)/PAGE_SIZE <= INVLPG_BREAK_EVEN_PAGES) { + while (start < end) { + __flush_tlb_single(start); + start += PAGE_SIZE; + } + } else + local_flush_tlb(); +} + #endif /* _ASM_X86_TLBFLUSH_H */
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