linux-kernel - [21/82] x86, kdump: Change copy_oldmem

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Message-Id: <20101119215640.476005407@clark.site>
Date:	Fri, 19 Nov 2010 13:55:42 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Cliff Wickman <cpw@....com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	kexec@...ts.infradead.org, Ingo Molnar <mingo@...e.hu>
Subject: [21/82] x86, kdump: Change copy_oldmem_page() to use cached addressing

2.6.35-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Cliff Wickman <cpw@....com>

commit 37a2f9f30a360fb03522d15c85c78265ccd80287 upstream.

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@....com>
Acked-by: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: kexec@...ts.infradead.org
LKML-Reference: <E1OtMLz-0001yp-Ia@...09.americas.sgi.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 arch/x86/kernel/crash_dump_64.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kernel/crash_dump_64.c
+++ b/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;

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