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. Cheers, Valentin Revisions ========= v1 -> v2 ++++++++ o Dropped the in-kernel osnoise_sample changes and made it all userspace Valentin Schneider (4): rtla/osnoise: Add IPI tracking cmdline option rtla/osnoise: Record IPI count in osnoise top rtla/osnoise: Trace IPI events when recording a trace file rtla/osnoise: Leverage IPI event filters when tracing a subset of CPUs Documentation/tools/rtla/rtla-osnoise-top.rst | 4 + tools/tracing/rtla/src/cli.c | 1 + tools/tracing/rtla/src/cli_p.h | 3 + tools/tracing/rtla/src/common.c | 2 +- tools/tracing/rtla/src/common.h | 3 +- tools/tracing/rtla/src/osnoise.c | 17 +- tools/tracing/rtla/src/osnoise_top.c | 153 +++++++++++++++++- 7 files changed, 179 insertions(+), 4 deletions(-) -- 2.54.0
