From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36200) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WxG8W-0006CL-9N for qemu-devel@nongnu.org; Wed, 18 Jun 2014 09:42:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WxG8Q-000092-53 for qemu-devel@nongnu.org; Wed, 18 Jun 2014 09:42:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:10792) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WxG8P-00008w-T8 for qemu-devel@nongnu.org; Wed, 18 Jun 2014 09:42:42 -0400 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s5IDga09009024 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Wed, 18 Jun 2014 09:42:36 -0400 From: Paolo Bonzini Date: Wed, 18 Jun 2014 15:42:08 +0200 Message-Id: <1403098928-30749-12-git-send-email-pbonzini@redhat.com> In-Reply-To: <1403098928-30749-1-git-send-email-pbonzini@redhat.com> References: <1403098928-30749-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PULL 11/11] memory: Don't call memory_region_update_coalesced_range if nothing changed List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Fam Zheng From: Fam Zheng 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 --- memory.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/memory.c b/memory.c index 85798b0..4895e25 100644 --- a/memory.c +++ b/memory.c @@ -1332,6 +1332,7 @@ 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; @@ -1340,8 +1341,12 @@ 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) -- 1.8.3.1