On Mon, 27 Apr 2020 11:34:32 +0100 "Dr. David Alan Gilbert" <dgilb...@redhat.com> wrote:
> * Lukas Straub (lukasstra...@web.de) wrote: > > On Sat, 11 Apr 2020 19:16:54 +0200 > > Lukas Straub <lukasstra...@web.de> wrote: > > > > > Hello Everyone, > > > I did some Benchmarking with iperf3 and memtester (to dirty some guest > > > memory) > > > of colo performance in qemu 4.2.0 and in qemu 5.0.0-rc2 > > > with my bugfixes on top.( > > > https://lists.nongnu.org/archive/html/qemu-devel/2020-04/msg01432.html ) > > > > > > I have taken the average over 4 runs. > > > Client-to-server tcp bandwidth rose slightly from ~83.98 Mbit/s to ~89.40 > > > Mbits. > > > Server-to-client tcp bandwidth fell from ~9.73 Mbit/s to ~1.79 Mbit/s. > > > Client-to-server udp bandwidth stayed the same at 1.05 Mbit/s > > > and jitter rose from ~5.12 ms to ~10.77 ms. > > > Server-to-client udp bandwidth fell from ~380.5 Kbit/s to ~33.6 Kbit/s > > > and jitter rose from ~41.74 ms to ~83976.15 ms (!). > > > > > > I haven't looked closely into it, but i think > > > 0393031a16735835a441b6d6e0495a1bd14adb90 "COLO: Optimize memory back-up > > > process" > > > is the culprint as it reduces vm downtime for the checkpoints but > > > increases > > > the overall checkpoint time and we can only release miscompared primary > > > packets > > > after the checkpoint is completely finished. > > > > > > Another thing that I noticed: With 4.2.0, the secondary qemu uses thrice > > > the amount of gest memory. With 5.0.0-rc2 it's just double the amount of > > > guest memory. So maybe the ram cache isn't working properly? > > > > > > Regards, > > > Lukas Straub > > > > Hmm, > > I looked at my test again and saw that the results where very noisy, so > > qemu 5.0.0-rc2 > > being slower was just a coincidence. I did increase the test time and the > > results are > > more meaningful now. Now qemu 5.0.0-rc2 is around the same speed and still > > faster > > in the client-to-server tcp case. > > > > Sorry for the noise. > > Is it back to using 3x RAM in the secondary? No. > Dave > > > > > Regards, > > Lukas Straub > > > -- > Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK >
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