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. Brian
