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| author | Cliff Wickman <cpw@sgi.com> | 2010-09-16 11:44:02 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-11-22 10:47:31 -0800 |
| commit | 9809892e2ccb494ad97599a018788f5abe8f7842 (patch) | |
| tree | 6d1e74277471662785b098c9fed0a1b34dea6ed6 | |
| parent | 183308db7612a1b46a2b6355e83d93a4a8950771 (diff) | |
| download | lwn-9809892e2ccb494ad97599a018788f5abe8f7842.tar.gz lwn-9809892e2ccb494ad97599a018788f5abe8f7842.zip | |
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>
| -rw-r--r-- | arch/x86/include/asm/io.h | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/crash_dump_64.c | 1 | ||||
| -rw-r--r-- | mm/vmalloc.c | 9 |
3 files changed, 11 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; } diff --git a/mm/vmalloc.c b/mm/vmalloc.c index c2287313b985..680dcbb2d91e 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -513,6 +513,15 @@ static atomic_t vmap_lazy_nr = ATOMIC_INIT(0); static void purge_fragmented_blocks_allcpus(void); /* + * called before a call to iounmap() if the caller wants vm_area_struct's + * immediately freed. + */ +void set_iounmap_nonlazy(void) +{ + atomic_set(&vmap_lazy_nr, lazy_max_pages()+1); +} + +/* * Purges all lazily-freed vmap areas. * * If sync is 0 then don't purge if there is already a purge in progress. |