linux/include
Takuya Yoshikawa 515a01279a KVM: pre-allocate one more dirty bitmap to avoid vmalloc()
Currently x86's kvm_vm_ioctl_get_dirty_log() needs to allocate a bitmap by
vmalloc() which will be used in the next logging and this has been causing
bad effect to VGA and live-migration: vmalloc() consumes extra systime,
triggers tlb flush, etc.

This patch resolves this issue by pre-allocating one more bitmap and switching
between two bitmaps during dirty logging.

Performance improvement:
  I measured performance for the case of VGA update by trace-cmd.
  The result was 1.5 times faster than the original one.

  In the case of live migration, the improvement ratio depends on the workload
  and the guest memory size. In general, the larger the memory size is the more
  benefits we get.

Note:
  This does not change other architectures's logic but the allocation size
  becomes twice. This will increase the actual memory consumption only when
  the new size changes the number of pages allocated by vmalloc().

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2011-01-12 11:28:46 +02:00
..
acpi ACPI: video: fix build for CONFIG_ACPI=n 2010-12-11 02:01:46 -05:00
asm-generic asm-generic/stat.h: support 64-bit file time_t for stat() 2010-11-01 15:31:29 -04:00
crypto Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2010-10-24 13:41:39 -07:00
drm drm/i915: announce to userspace that the bsd ring is coherent 2010-12-05 10:40:39 +00:00
keys
linux KVM: pre-allocate one more dirty bitmap to avoid vmalloc() 2011-01-12 11:28:46 +02:00
math-emu
media Merge branch 'bkl_removal' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6 2010-12-17 09:28:17 -08:00
mtd mtd: Define MLC Flash as a different flash type 2010-10-25 00:50:20 +01:00
net filter: fix sk_filter rcu handling 2010-12-06 09:29:43 -08:00
pcmcia pcmcia: IOCARD is also required for using IRQs 2010-10-22 08:46:36 +02:00
rdma IB/core: Add VLAN support for IBoE 2010-10-25 10:20:39 -07:00
rxrpc
scsi SCSI host lock push-down 2010-11-16 13:33:23 -08:00
sound ARM: mach-shmobile: ap4evb: FSI clock use proper process for HDMI 2010-11-24 15:29:56 +09:00
trace KVM: x86: trace "exit to userspace" event 2011-01-12 11:28:44 +02:00
video fbdev: da8xx: punt duplicated FBIO_WAITFORVSYNC define 2010-11-16 10:14:22 +09:00
xen xen: Provide a variant of __RING_SIZE() that is an integer constant expression 2010-12-15 12:34:28 -08:00
Kbuild