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Date: Wed, 08 Sep 2010 10:14:27 -0500 From: Cliff Wickman <cpw@....com> To: kexec@...ts.infradead.org, mingo@...e.hu Cc: linux-kernel@...r.kernel.org Subject: [PATCH] x86: copy_oldmem_page using cached addressing From: Cliff Wickman <cpw@....com> 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. (Does anyone know of a reason why copy_oldmem_page() would need to use uncached addresses?) Diffed against 2.6.36-rc3 Signed-off-by: Cliff Wickman <cpw@....com> --- arch/x86/kernel/crash_dump_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linus.current/arch/x86/kernel/crash_dump_64.c =================================================================== --- linus.current.orig/arch/x86/kernel/crash_dump_64.c +++ linus.current/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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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