On Tue, Oct 29, 2013 at 12:05:27PM -0700, Michael Dalton wrote: > Agreed Eric, the buffer size should be increased so that we can accommodate a > MTU-sized packet + mergeable virtio net header in a single buffer. I will send > a patch to fix shortly cleaning up the #define headers as Rusty indicated and > increasing the buffer size slightly by VirtioNet header size bytes per Eric. > > Jason, I'll followup with you directly - I'd like to know your exact workload > (single steam or multi-stream netperf?), VM configuration, etc, and also see if > the nit that Erichas pointed out affects your results. It is also > worth noting that > we may want to tune the queue sizes for your benchmarks, e.g, by reducing > buffer size from 4KB to MTU-sized but keeping queue length constant, we're > implicitly decreasing the number of bytes stored in the VirtioQueue for the > VirtioNet device, so increasing the queue size may help. > > Best, > > Mike Well we have 256 descriptors per queue, each descriptor is 16 bytes already and they have to be physically contigious. I don't think we can easily increase the queue size much more without risking memory allocation failures on busy systems. I guess one approach is to do something like: if (queue size > 1024) use small buffers else use 4K buffers. That would reduce the risk of regressions for existing users. -- MST _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
