From 1928814fabf0662556cd28f248b3c1069a2c3383 Mon Sep 17 00:00:00 2001 From: Cliff Wickman Date: Thu, 16 Sep 2010 11:44:02 -0500 Subject: 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 Cc: Andrew Morton Cc: kexec@lists.infradead.org LKML-Reference: Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/io.h | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/include/asm/io.h') diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h index 73739322b6d..6a63b86c64a 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" -- cgit v1.2.3-18-g5258