From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39951) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZUTHS-00088N-Gz for qemu-devel@nongnu.org; Wed, 26 Aug 2015 01:29:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZUTHP-00060F-Aj for qemu-devel@nongnu.org; Wed, 26 Aug 2015 01:29:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55700) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZUTHP-0005zt-4v for qemu-devel@nongnu.org; Wed, 26 Aug 2015 01:29:47 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (Postfix) with ESMTPS id 53A578CF45 for ; Wed, 26 Aug 2015 05:29:46 +0000 (UTC) Message-ID: <55DD4EC4.3070908@redhat.com> Date: Wed, 26 Aug 2015 13:29:40 +0800 From: Jason Wang MIME-Version: 1.0 References: <1440147950-1178-1-git-send-email-jasowang@redhat.com> <1440147950-1178-6-git-send-email-jasowang@redhat.com> <20150825144732-mutt-send-email-mst@redhat.com> In-Reply-To: <20150825144732-mutt-send-email-mst@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 5/6] virtio-pci: introduce pio notification capability for modern device List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: qemu-devel@nongnu.org On 08/25/2015 07:48 PM, Michael S. Tsirkin wrote: > On Fri, Aug 21, 2015 at 05:05:49PM +0800, Jason Wang wrote: >> > We used to use mmio for notification. This could be slow on some arch >> > (e.g on x86 without EPT). So this patch introduces pio bar and a pio >> > notification cap for modern device. This ability is enabled through >> > property "modern-pio-notify" for virtio pci devices and was disabled >> > by default. Management can enable when it thinks it was needed. >> > >> > Benchmarks shows almost no obvious difference with legacy device. >> > Thanks Wenli Quan for the benchmarking. >> > >> > Cc: Michael S. Tsirkin >> > Signed-off-by: Jason Wang > I don't really care much about non-EPT hosts, but if you propose > a patch to optimize them, it should be accompanied by numbers > showing the performance difference. > According to the test, PIO is a little bit faster than fast mmio in some specific TCP_RR case: modern device fast mmio vs modern device pio: TCP_RR: size/session/+transaction rate%/+cpu%/-+per cpu%/ 64/1/[+1.5646%]/+5.6604%/-4.3415%/ 64/25/+0.3003%/-0.4517%/+0.7486%/ ... 256/1/[+1.0046%]/[-6.5238%]/[+7.0673%]/ So the improvement is almost as much as previous patch.