On 5/22/19 2:09 AM, Paolo Valente wrote: > > First, thank you very much for testing my patches, and, above all, for > sharing those huge traces! > > According to the your traces, the residual 20% lower throughput that you > record is due to the fact that the BFQ injection mechanism takes a few > hundredths of seconds to stabilize, at the beginning of the workload. > During that setup time, the throughput is equal to the dreadful ~60-90 KB/s > that you see without this new patch. After that time, there > seems to be no loss according to the trace. > > The problem is that a loss lasting only a few hundredths of seconds is > however not negligible for a write workload that lasts only 3-4 > seconds. Could you please try writing a larger file? > I tried running dd for longer (about 100 seconds), but still saw around 1.4 MB/s throughput with BFQ, and between 1.5 MB/s - 1.6 MB/s with mq-deadline and noop. But I'm not too worried about that difference. > In addition, I wanted to ask you whether you measured BFQ throughput > with traces disabled. This may make a difference. > The above result (1.4 MB/s) was obtained with traces disabled. > After trying writing a larger file, you can try with low_latency on. > On my side, it causes results to become a little unstable across > repetitions (which is expected). > With low_latency on, I get between 60 KB/s - 100 KB/s. Regards, Srivatsa VMware Photon OS
