On 26/06/26 06:26, Steven Rostedt wrote: > On Wed, 17 Jun 2026 15:17:55 +0200 > Valentin Schneider <[email protected]> wrote: > >> Hi folks, >> >> So I've seen a few times now reports of latency spikes caused by IPIs, >> usually >> because of isolation misconfiguration, but only detected at the tail of end >> e.g. a 24h timerlat run. >> >> It's not because those IPIs are rare, but rather that they don't by >> themselves >> cause a monitered CPU to reach the latency threshold, it's usually a combined >> interference that gets us there. >> >> I'd like to make it easier to detect such misconfigurations and thus IPIs >> hitting supposedly-isolated CPUs. I initially kludged a timerlat option to >> stop >> tracing as soon as an IPI was sent to a monitored CPU, regardless of the >> latency >> threshold. It sort of did the trick, but Tomáš convinced me timerlat wasn't >> really the place for that. >> >> So here's IPI tracking added to osnoise. This time around fully in >> userspace, as >> Tomáš pointed out to me that this will make it a lot easier to deploy to >> older >> kernels. >> >> Based on top of linux/next at 'next-20260616' to have the latest libsubcmd >> changes. >> > > Hi Valentin, > > My new job actually makes me very interested in IPI interference, and > this patch set looks *very* interesting. I'm currently finishing up my > orientation and hopefully next week I can start catching up on all my > email. >
Welcome back :-) If IPIs are your thing, you may also have a look at [1]. I'm working on a v10 following some (surprisingly) useful feedback from Sashiko. [1]: https://lore.kernel.org/lkml/[email protected]/ > I'll try to take a deeper look at this in the coming weeks. > Thanks! > -- Steve
