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

proc: switch /proc/cmdline to seq_file

2008-10-23 14:29:04 +04:00

consoles.c

console: rename acquire/release_console_sem() to console_lock/unlock()

2011-01-26 10:50:06 +10:00

cpuinfo.c

proc: move /proc/cpuinfo code to fs/proc/cpuinfo.c

2008-10-23 15:05:11 +04:00

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

proc: move /proc/interrupts boilerplate code to fs/proc/interrupts.c

2008-10-23 15:15:46 +04:00

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

fs/proc/mmu.c: headers butchery

2007-10-17 08:42:48 -07:00

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

proc: switch /proc/version to seq_file

2008-10-23 14:19:58 +04:00

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