On Tue, 2025-02-04 at 14:35 +0100, Tomas Glozar wrote: > po 3. 2. 2025 v 10:04 odesílatel Tomas Glozar <[email protected]> > napsal: > > A proof-of-concept bpftrace script using this feature: > > https://gitlab.com/-/snippets/4801190 > > > > I added another PoC using event histograms to the snippet. That one > captures data from all CPUs, and thus can be used for testing on > machines with a high number of CPUs where rtla cannot keep up with > timerlat samples (in our measurements, >100). > > There seems to be an issue with division where most values are > rounded up, e.g.: > max: 135 timer_latency: 134657 > > This also affects the main histogram and seems to be specific to the > event histogram PoC. The bpftrace one shows exactly the same results > as rtla when run concurrently with it. Another difference compared to > the bpftrace PoC is that you have to calculate averages manually from > the latency sum and the sample count. > > Tomas >
The patch and scripts using the new tracepoints produce reasonable results on a large arm64 machine (128 cores). Tested-by: Gabriele Monaco <[email protected]> Thanks, Gabriele
