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linux/fs/proc
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Olaf Hering 997c136f51 fs/proc/vmcore.c: add hook to read_from_oldmem() to check for non-ram pages 
The balloon driver in a Xen guest frees guest pages and marks them as
mmio.  When the kernel crashes and the crash kernel attempts to read the
oldmem via /proc/vmcore a read from ballooned pages will generate 100%
load in dom0 because Xen asks qemu-dm for the page content.  Since the
reads come in as 8byte requests each ballooned page is tried 512 times.

With this change a hook can be registered which checks wether the given
pfn is really ram.  The hook has to return a value > 0 for ram pages, a
value < 0 on error (because the hypercall is not known) and 0 for non-ram
pages.

This will reduce the time to read /proc/vmcore.  Without this change a
512M guest with 128M crashkernel region needs 200 seconds to read it, with
this change it takes just 2 seconds.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-26 17:12:37 -07:00
..
array.c proc: constify status array 2011-05-26 17:12:36 -07:00
base.c proc: put check_mem_permission after __get_free_page in mem_write 2011-05-26 17:12:37 -07:00
cmdline.c
consoles.c console: rename acquire/release_console_sem() to console_lock/unlock() 2011-01-26 10:50:06 +10:00
cpuinfo.c
devices.c proc: use seq_puts()/seq_putc() where possible 2011-01-13 08:03:16 -08:00
generic.c airo: correct proc entry creation interfaces 2011-05-16 14:25:28 -04:00
inode.c ns: proc files for namespace naming policy. 2011-05-10 14:31:44 -07:00
internal.h Merge git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/linux-2.6-nsfd 2011-05-25 18:10:16 -07:00
interrupts.c
Kconfig kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
kcore.c /proc/kcore: fix seeking 2011-01-13 08:03:17 -08:00
kmsg.c procfs: Use generic_file_llseek in /proc/kmsg 2010-04-09 16:35:41 +02:00
loadavg.c sched, timers: cleanup avenrun users 2009-05-15 15:32:45 +02:00
Makefile ns: proc files for namespace naming policy. 2011-05-10 14:31:44 -07:00
meminfo.c thp: transparent hugepage vmstat 2011-01-13 17:32:43 -08:00
mmu.c
namespaces.c ns proc: Return -ENOENT for a nonexistent /proc/self/ns/ entry. 2011-05-24 15:30:33 -07:00
nommu.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
page.c thp: remove PG_buddy 2011-01-13 17:32:43 -08:00
proc_devtree.c of/flattree: Drop an uninteresting message to pr_debug level 2011-03-02 13:45:18 -07:00
proc_net.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
proc_sysctl.c Merge branch 'next' into for-linus 2011-03-16 09:41:17 +11:00
proc_tty.c proc: use seq_puts()/seq_putc() where possible 2011-01-13 08:03:16 -08:00
root.c procfs: kill the global proc_mnt variable 2011-03-23 19:46:58 -07:00
softirqs.c proc: use seq_puts()/seq_putc() where possible 2011-01-13 08:03:16 -08:00
stat.c proc/stat: use defined macro KMALLOC_MAX_SIZE 2011-05-26 17:12:37 -07:00
task_mmu.c proc: fix pagemap_read() error case 2011-05-26 17:12:37 -07:00
task_nommu.c report errors in /proc/*/*map* sanely 2011-03-23 16:36:50 -04:00
uptime.c [PATCH] Fix idle time field in /proc/uptime 2009-09-24 10:16:24 +02:00
version.c
vmcore.c fs/proc/vmcore.c: add hook to read_from_oldmem() to check for non-ram pages 2011-05-26 17:12:37 -07:00