On Thu, Oct 28, 2010 at 10:14:22AM -0700, Shirley Ma wrote: > > > Two ideas: > > 1. How about writing out used, just delaying the signal? > > This way we don't have to queue separately. > > This improves some performance, but not as good as delaying > both used and signal. Since delaying used buffers combining > multiple small copies to a large copy, which saves more CPU > utilization and increased some BW. Hmm. I don't yet understand. We are still doing copies into the per-vq buffer, and the data copied is really small. Is it about cache line bounces? Could you try figuring it out? > > 2. How about flushing out queued stuff before we exit > > the handle_tx loop? That would address most of > > the spec issue. > > The performance is almost as same as the previous patch. I will resubmit > the modified one, adding vhost_add_used_and_signal_n after handle_tx > loop for processing pending queue. > > This patch was a part of modified macvtap zero copy which I haven't > submitted yet. I found this helped vhost TX in general. This pending > queue will be used by DMA done later, so I put it in vq instead of a > local variable in handle_tx. > > Thanks > Shirley BTW why do we need another array? Isn't heads field exactly what we need here? -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
