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
base.c
cmdline.c
consoles.c
cpuinfo.c
devices.c
generic.c
inode.c
internal.h
interrupts.c
Kconfig
kcore.c
kmsg.c
loadavg.c
Makefile
meminfo.c
mmu.c
namespaces.c
nommu.c
page.c
proc_devtree.c
proc_net.c
proc_sysctl.c
proc_tty.c
root.c
softirqs.c
stat.c
task_mmu.c
task_nommu.c
uptime.c
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