On 2025-04-15 12:26:13 [-0400], Aaron Conole wrote: > I'm going to reply here, but I need to bisect a bit more (though I > suspect the results below are due to 11/18). When I tested with this > patch there were lots of "unexplained" latency spikes during processing > (note, I'm not doing PREEMPT_RT in my testing, but I guess it would > smooth the spikes out at the cost of max performance). > > With the series: > [SUM] 0.00-300.00 sec 3.28 TBytes 96.1 Gbits/sec 9417 sender > [SUM] 0.00-300.00 sec 3.28 TBytes 96.1 Gbits/sec receiver > > Without the series: > [SUM] 0.00-300.00 sec 3.26 TBytes 95.5 Gbits/sec 149 sender > [SUM] 0.00-300.00 sec 3.26 TBytes 95.5 Gbits/sec receiver > > And while the 'final' numbers might look acceptable, one thing I'll note > is I saw multiple stalls as: > > [ 5] 57.00-58.00 sec 128 KBytes 903 Kbits/sec 0 4.02 MBytes > > But without the patch, I didn't see such stalls. My testing: > > 1. Install openvswitch userspace and ipcalc > 2. start userspace. > 3. Setup two netns and connect them (I have a more complicated script to > set up the flows, and I can send that to you) > 4. Use iperf3 to test (-P5 -t 300) > > As I wrote I suspect the locking in 11 is leading to these stalls, as > the data I'm sending shouldn't be hitting the frag path. > > Do these results seem expected to you?
You have slightly better throughput but way more retries. I wouldn't expect that. And then the stall. Patch 10 & 12 move per-CPU variables around and makes them "static" rather than allocating them at module init time. I would not expect this to have a negative impact. Patch #11 assigns the current thread to a variable and clears it again. The remaining lockdep code disappears. The whole thing runs with BH disabled so no preemption. I can't explain what you observe here. Unless it is a random glitch please send the script and I try to take a look. Sebastian _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev
