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authorCliff Wickman <cpw@sgi.com>2010-09-16 11:44:02 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2010-11-22 10:47:31 -0800
commit9809892e2ccb494ad97599a018788f5abe8f7842 (patch)
tree6d1e74277471662785b098c9fed0a1b34dea6ed6 /arch
parent183308db7612a1b46a2b6355e83d93a4a8950771 (diff)
mm, x86: Saving vmcore with non-lazy freeing of vmas
commit 3ee48b6af49cf534ca2f481ecc484b156a41451d upstream. During the reading of /proc/vmcore the kernel is doing ioremap()/iounmap() repeatedly. And the buildup of un-flushed vm_area_struct's is causing a great deal of overhead. (rb_next() is chewing up most of that time). This solution is to provide function set_iounmap_nonlazy(). It causes a subsequent call to iounmap() to immediately purge the vma area (with try_purge_vmap_area_lazy()). With this patch we have seen the time for writing a 250MB compressed dump drop from 71 seconds to 44 seconds. Signed-off-by: Cliff Wickman <cpw@sgi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: kexec@lists.infradead.org LKML-Reference: <E1OwHZ4-0005WK-Tw@eag09.americas.sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/io.h1
-rw-r--r--arch/x86/kernel/crash_dump_64.c1
2 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 73739322b6d0..6a63b86c64a1 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -172,6 +172,7 @@ static inline void __iomem *ioremap(resource_size_t offset, unsigned long size)
extern void iounmap(volatile void __iomem *addr);
+extern void set_iounmap_nonlazy(void);
#ifdef CONFIG_X86_32
# include "io_32.h"
diff --git a/arch/x86/kernel/crash_dump_64.c b/arch/x86/kernel/crash_dump_64.c
index 045b36cada65..ce96a6b575b7 100644
--- a/arch/x86/kernel/crash_dump_64.c
+++ b/arch/x86/kernel/crash_dump_64.c
@@ -46,6 +46,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
} else
memcpy(buf, vaddr + offset, csize);
+ set_iounmap_nonlazy();
iounmap(vaddr);
return csize;
}