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x86, kdump: Change copy_oldmem_page() to use cached addressing

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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 <cpw@sgi.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: kexec@lists.infradead.org
Cc: <stable@kernel.org> # as far back as it would apply
LKML-Reference: <E1OtMLz-0001yp-Ia@eag09.americas.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Cliff Wickman 2010-09-08 10:14:27 -05:00 • committed by Ingo Molnar
commit 37a2f9f30a
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kernel/crash_dump_64.c
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@ -34,7 +34,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
if (!csize)
return 0;
vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
vaddr = ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE);
if (!vaddr)
return -ENOMEM;