@ Han, I guess FLOW_MISS_MAX_BATCH should be the right place to change. For my understanding, ovs userspace will batch all the packets it received and the put packets from same flow into a "group", one group for each flow. So I guess there are two levels of "batching".
On Thu, Jan 16, 2014 at 12:17 PM, Zhou, Han <[email protected]> wrote: > Hi Xiaoye, > > > Is there any way to disable this batching mechanism in the ovs kernel so > that each upcall only contains one packet? > Batching is a mechanism of the user space upcall handler rather than OVS > kernel. > To disable it you can change below macro in ofproto/ofproto-dpif-upcall.h: > #define FLOW_MISS_MAX_BATCH 50 => 1 > > However, I wonder how would batching affect your RTT result. > On Wed, Jan 15, 2014 at 5:11 PM, Ben Pfaff <[email protected]> wrote: > > As the rate > > increases, I guess that a batch contains more than one packet, and > > it's likely that the batches mix up SYNs and SYN-ACKs, possibly > > reducing the latency. > > @Ben, even if the batches mix up SYNs and SYN-ACKs, they are from different > Flows. For SYN and SYN-ACK pairs of each single flow, they can never be > mixed in the same batch, because SYN-ACK is not sent out until SYN is > delivered > to the receiver. So in my opinion, batching can improve the whole > throughput but > cannot explain the better STT. Did I miss anything here? > > @Xiaoye, maybe you can change FLOW_MISS_MAX_BATCH to different numbers to > verify. > > Best regards, > Han > _______________________________________________ > discuss mailing list > [email protected] > http://openvswitch.org/mailman/listinfo/discuss > > -- Xiaoye (Steven) Sun, Ph.D. Student Department of Electrical and Computer Engineering (ECE) & Department of Computer Science (CS) George R. Brown School of Engineering Rice University, Houston, Texas, USA
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