From 67f736a89722dcaa425c70510c080e95216a165f Mon Sep 17 00:00:00 2001 From: Fam Zheng Date: Thu, 19 Jun 2014 10:21:56 +0200 Subject: [PATCH 11/13] memory: Don't call memory_region_update_coalesced_range if nothing changed RH-Author: Fam Zheng Message-id: <1403173316-12035-1-git-send-email-famz@redhat.com> Patchwork-id: 59289 O-Subject: [RHEL-7.1/7.0.z qemu-kvm PATCH] memory: Don't call memory_region_update_coalesced_range if nothing changed Bugzilla: 1096645 RH-Acked-by: Amos Kong RH-Acked-by: Paolo Bonzini RH-Acked-by: Laszlo Ersek Brew: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=7596269 BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1096645 With huge number of PCI devices in the system (for example, 200 virtio-blk-pci), this unconditional call can slow down emulation of irrelevant PCI operations drastically, such as a BAR update on a device that has no coalescing region. So avoid it. Signed-off-by: Fam Zheng Signed-off-by: Paolo Bonzini (cherry picked from commit ab5b3db5d711b290d63e954dc64647dd51cef962) Signed-off-by: Fam Zheng --- memory.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) Signed-off-by: Miroslav Rezanina --- memory.c | 7 ++++++- 1 files changed, 6 insertions(+), 1 deletions(-) diff --git a/memory.c b/memory.c index edaf6fd..a71d096 100644 --- a/memory.c +++ b/memory.c @@ -1210,6 +1210,7 @@ void memory_region_add_coalescing(MemoryRegion *mr, void memory_region_clear_coalescing(MemoryRegion *mr) { CoalescedMemoryRange *cmr; + bool updated = false; qemu_flush_coalesced_mmio_buffer(); mr->flush_coalesced_mmio = false; @@ -1218,8 +1219,12 @@ void memory_region_clear_coalescing(MemoryRegion *mr) cmr = QTAILQ_FIRST(&mr->coalesced); QTAILQ_REMOVE(&mr->coalesced, cmr, link); g_free(cmr); + updated = true; + } + + if (updated) { + memory_region_update_coalesced_range(mr); } - memory_region_update_coalesced_range(mr); } void memory_region_set_flush_coalesced(MemoryRegion *mr) -- 1.7.1