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. I'll try to take a deeper look at this in the coming weeks. -- Steve
