Brian Norris <briannorris@xxxxxxxxxxxx> writes: > Hi, > > Thanks Pin-yen for most of the investigation here and for pushing the > patch. With some additional information though, I might suggest *not* > landing this patch at the moment. More details appended: > > On Sat, Jun 10, 2023 at 01:41:51AM +0800, Pin-yen Lin wrote: >> I realized that I might have over-simplified the background and the >> impact of this patch... >> >> The short answer to the question is that the throughput improved from >> 100 mbps to 180 mbps. The test was run on ChromeOS's v5.15 kernel >> fork. More detailed test setting is mentioned in [1]. >> >> However, the throughput of the same test case on our v4.19 kernel is >> 320 mbps. That is, we observed a 320 mbps --> 100 mbps regression when >> we tried to update the kernel version. This patch is more like a >> mitigation of the regression. It improves the throughput, even though >> it is still not as good as the older kernel. >> >> That being said, this patch does improve the throughput, so we think >> this patch can be landed into the mainline kernel. >> >> Best regards, >> Pin-yen >> >> [1]: https://lore.kernel.org/all/ZFvpJb9Dh0FCkLQA@xxxxxxxxxx/ > > I (we?) was optimistic this would be an improvement (or at least, no > worse) due to some of the reasoning at [1]. And, the work here is just a > single work item, queued repeatedly to the same unbound workqueue. So > conceptually, it shouldn't be much different than a kthread_worker, > except for scheduler details -- where again, we'd think this should be > an improvement, as the scheduler would now better track load for the > task (mwifiex RX) in question. > > But additional testing on other mwifiex-based systems (RK3399 + PCIE > 8997) showed the inverse: some throughput drops on similar benchmarks, > from 110 Mbps to 80 Mbps. (Frankly, both numbers are significantly below > where we might like...) > > Considering we still don't have a full explanation for all the > performance differences we've been seeing (on either test platform), and > that at least one of our platforms showed a (smaller) regression, I > think we might want to do more research before committing to this. Yeah, I agree and I'll drop this. This is a really weird problem, I hope you can get to the bottom of it. -- https://patchwork.kernel.org/project/linux-wireless/list/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
