From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48700) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZU4nS-0000Be-Oi for qemu-devel@nongnu.org; Mon, 24 Aug 2015 23:21:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZU4nO-0008Pk-OB for qemu-devel@nongnu.org; Mon, 24 Aug 2015 23:21:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38276) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZU4nO-0008PF-HJ for qemu-devel@nongnu.org; Mon, 24 Aug 2015 23:21:10 -0400 Message-ID: <55DBDF20.6000505@redhat.com> Date: Tue, 25 Aug 2015 11:21:04 +0800 From: Jason Wang MIME-Version: 1.0 References: <1440147950-1178-1-git-send-email-jasowang@redhat.com> <1440147950-1178-5-git-send-email-jasowang@redhat.com> <20150824183026.413e37a3@bahia.local> In-Reply-To: <20150824183026.413e37a3@bahia.local> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 4/6] virtio-pci: use wildcard mmio eventfd for 1.0 notification cap List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Greg Kurz Cc: qemu-devel@nongnu.org, mst@redhat.com On 08/25/2015 12:30 AM, Greg Kurz wrote: > On Fri, 21 Aug 2015 17:05:48 +0800 > Jason Wang wrote: > >> > We use data match eventfd for 1.0 notification currently. This could >> > be slow since software decoding is needed for mmio exit. To speed this >> > up, we can switch to use wild card mmio eventfd for 1.0 notification >> > since we can examine the queue index directly from the writing >> > address. KVM kernel module can utilize this by registering it to fast >> > mmio bus which could be as fast as pio on ept capable machine. >> > >> > Lots of improvements were seen on a ept capable machine: >> > >> > Guest RX:(TCP) >> > size/session/+throughput%/+cpu%/-+per cpu%/ >> > 64/1/+1.6807%/[-16.2421%]/[+21.3984%]/ >> > 64/2/+0.6091%/[-11.0187%]/[+13.0678%]/ >> > 64/4/+0.0553%/[-5.9768%]/[+6.4155%]/ >> > 64/8/+0.1206%/[-4.0057%]/[+4.2984%]/ >> > 256/1/-0.0031%/[-10.1166%]/[+11.2517%]/ >> > 256/2/-0.5058%/[-6.1656%]/+6.0317%]/ >> > ... >> > >> > Guest TX:(TCP) >> > size/session/+throughput%/+cpu%/-+per cpu%/ >> > 64/1/[+18.9183%]/-0.2823%/[+19.2550%]/ >> > 64/2/[+13.5714%]/[+2.2675%]/[+11.0533%]/ >> > 64/4/[+13.1070%]/[+2.1817%]/[+10.6920%]/ >> > 64/8/[+13.0426%]/[+2.0887%]/[+10.7299%]/ >> > 256/1/[+36.2761%]/+6.3434%/[+28.1471%]/ >> > ... >> > 1024/1/[+44.8873%]/+2.0811%/[+41.9335%]/ >> > ... >> > 1024/4/+0.0228%/[-2.2044%]/[+2.2774%]/ >> > ... >> > 16384/2/+0.0127%/[-5.0346%]/[+5.3148%]/ >> > ... >> > 65535/1/[+0.0062%]/[-4.1183%]/[+4.3017%]/ >> > 65535/2/+0.0004%/[-4.2311%]/[+4.4185%]/ >> > 65535/4/+0.0107%/[-4.6106%]/[+4.8446%]/ >> > 65535/8/-0.0090%/[-5.5178%]/[+5.8306%]/ >> > >> > Latency:(TCP_RR) >> > size/session/+transaction rate%/+cpu%/-+per cpu%/ >> > 64/1/[+6.5248%]/[-9.2882%]/[+17.4322%]/ >> > 64/25/[+11.0854%]/[+0.8000%]/[+10.2038%]/ >> > 64/50/[+12.1076%]/[+2.4627%]/[+9.4131%]/ >> > 256/1/[+5.3677%]/[+10.5669%]/-4.7024%/ >> > 256/25/[+5.6402%]/-0.8962%/[+6.5955%]/ >> > 256/50/[+5.9685%]/[+1.7766%]/[+4.1188%]/ >> > 4096/1/+0.2508%/[-10.4941%]/[+12.0047%]/ >> > 4096/25/[+1.8533%]/-0.0273%/+1.8812%/ >> > 4096/50/[+1.2156%]/-1.4134%/+2.6667%/ >> > >> > Notes: data with '[]' is the one whose significance is greater than 95%. >> > >> > Thanks Wenli Quan for the benchmarking. >> > >> > Cc: Michael S. Tsirkin >> > Signed-off-by: Jason Wang >> > --- >> > hw/virtio/virtio-pci.c | 8 ++++---- >> > 1 file changed, 4 insertions(+), 4 deletions(-) >> > >> > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c >> > index d785623..fbd1f1f 100644 >> > --- a/hw/virtio/virtio-pci.c >> > +++ b/hw/virtio/virtio-pci.c >> > @@ -226,8 +226,8 @@ static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy, >> > } >> > virtio_queue_set_host_notifier_fd_handler(vq, true, set_handler); >> > if (modern) { >> > - memory_region_add_eventfd(modern_mr, modern_addr, 2, >> > - true, n, notifier); >> > + memory_region_add_eventfd(modern_mr, modern_addr, 0, >> > + false, n, notifier); > This calls for the following change in memory.c: > > static void adjust_endianness(MemoryRegion *mr, uint64_t *data, unsigned size) > { > - if (memory_region_wrong_endianness(mr)) { > + if (size && memory_region_wrong_endianness(mr)) { > > > otherwise we abort on PPC64. > Right, will fix this in V2. Thanks