On 09.04.25 15:21, Sebastian Andrzej Siewior wrote: > On 2025-04-09 08:41:44 [+0200], Jan Kiszka wrote: >> We are hunting for quite some time sporadic lock-ups or RT systems, >> first only in the field (sigh), now finally also in the lab. Those have >> a fairly high overlap with what was described here. Our baselines so >> far: 6.1-rt, Debian and vanilla. We are currently preparing experiments >> with latest mainline. >> >> While this thread remained silent afterwards, we have found [1][2][3] as >> apparently related. But this means we are still with this RT bug, even >> in latest 6.15-rc1? > > Not sure the commits are related. The problem here is that RW locks are > not really real time friendly. Frederick had a simple fix to it > https://lore.kernel.org/all/20210825132754.GA895675@lothringen/ > > but yeah. The alternative, which I didn't look into, would be to replace > the reader side with RCU so we would just have the writer lock. That > mean we need to RW lock because of performance… > We know that epoll is not a good idea for RT programs. However, our problem is that already non-RT programs manage to lock up an RT-enabled system. We are currently collecting more data to show what we are seeing, plus will try out the latest patches on the latest kernels. Jan -- Siemens AG, Foundational Technologies Linux Expert Center
