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Date: Thu, 14 Jul 2011 12:38:05 -0700 From: Roopa Prabhu <roprabhu@...co.com> To: "Michael S. Tsirkin" <mst@...hat.com>, Tom Lendacky <tahm@...ux.vnet.ibm.com> CC: Krishna Kumar2 <krkumar2@...ibm.com>, Christian Borntraeger <borntraeger@...ibm.com>, Carsten Otte <cotte@...ibm.com>, <habanero@...ux.vnet.ibm.com>, Heiko Carstens <heiko.carstens@...ibm.com>, <kvm@...r.kernel.org>, <lguest@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>, <linux-s390@...r.kernel.org>, <linux390@...ibm.com>, <netdev@...r.kernel.org>, Rusty Russell <rusty@...tcorp.com.au>, Martin Schwidefsky <schwidefsky@...ibm.com>, <steved@...ibm.com>, <virtualization@...ts.linux-foundation.org>, Shirley Ma <xma@...ibm.com> Subject: Re: RFT: virtio_net: limit xmit polling On 6/29/11 1:42 AM, "Michael S. Tsirkin" <mst@...hat.com> wrote: > On Tue, Jun 28, 2011 at 11:08:07AM -0500, Tom Lendacky wrote: >> On Sunday, June 19, 2011 05:27:00 AM Michael S. Tsirkin wrote: >>> OK, different people seem to test different trees. In the hope to get >>> everyone on the same page, I created several variants of this patch so >>> they can be compared. Whoever's interested, please check out the >>> following, and tell me how these compare: >>> >>> kernel: >>> >>> git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git >>> >>> virtio-net-limit-xmit-polling/base - this is net-next baseline to test >>> against virtio-net-limit-xmit-polling/v0 - fixes checks on out of capacity >>> virtio-net-limit-xmit-polling/v1 - previous revision of the patch >>> this does xmit,free,xmit,2*free,free >>> virtio-net-limit-xmit-polling/v2 - new revision of the patch >>> this does free,xmit,2*free,free >>> >> >> Here's a summary of the results. I've also attached an ODS format >> spreadsheet >> (30 KB in size) that might be easier to analyze and also has some pinned VM >> results data. I broke the tests down into a local guest-to-guest scenario >> and a remote host-to-guest scenario. >> >> Within the local guest-to-guest scenario I ran: >> - TCP_RR tests using two different messsage sizes and four different >> instance counts among 1 pair of VMs and 2 pairs of VMs. >> - TCP_STREAM tests using four different message sizes and two different >> instance counts among 1 pair of VMs and 2 pairs of VMs. >> >> Within the remote host-to-guest scenario I ran: >> - TCP_RR tests using two different messsage sizes and four different >> instance counts to 1 VM and 4 VMs. >> - TCP_STREAM and TCP_MAERTS tests using four different message sizes and >> two different instance counts to 1 VM and 4 VMs. >> over a 10GbE link. > > roprabhu, Tom, > > Thanks very much for the testing. So on the first glance > one seems to see a significant performance gain in V0 here, > and a slightly less significant in V2, with V1 > being worse than base. But I'm afraid that's not the > whole story, and we'll need to work some more to > know what really goes on, please see below. > > > Some comments on the results: I found out that V0 because of mistake > on my part was actually almost identical to base. > I pushed out virtio-net-limit-xmit-polling/v1a instead that > actually does what I intended to check. However, > the fact we get such a huge distribution in the results by Tom > most likely means that the noise factor is very large. > > > From my experience one way to get stable results is to > divide the throughput by the host CPU utilization > (measured by something like mpstat). > Sometimes throughput doesn't increase (e.g. guest-host) > by CPU utilization does decrease. So it's interesting. > > > Another issue is that we are trying to improve the latency > of a busy queue here. However STREAM/MAERTS tests ignore the latency > (more or less) while TCP_RR by default runs a single packet per queue. > Without arguing about whether these are practically interesting > workloads, these results are thus unlikely to be significantly affected > by the optimization in question. > > What we are interested in, thus, is either TCP_RR with a -b flag > (configure with --enable-burst) or multiple concurrent > TCP_RRs. > > > Michael, below are some numbers I got from one round of runs. Thanks, Roopa 256byte req/response. Vcpus and irqs were pinned to 4 cores and the cpu utilization is Avg across 4 cores. base: Numof concurrent TCP_RRs Num of transactions/sec host cpu-util(%) 1 7982.93 15.72 25 67873 28.84 50 112534 52.25 100 192057 86.54 v1 Numof concurrent TCP_RRs Num of transactions/sec host cpu-util(%) 1 7970.94 10.8 25 65496.8 28 50 109858 53.22 100 190155 87.5 v1a Numof concurrent TCP_RRs Num of transactions/sec host cpu-util (%) 1 7979.81 9.5 25 66786.1 28 50 109552 51 100 190876 88 v2 Numof concurrent TCP_RRs Num of transactions/sec host cpu-util (%) 1 7969.87 16.5 25 67780.1 28.44 50 114966 54.29 100 177982 79.9 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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