On Tue, Jan 21, 2025 at 03:57:23PM +1100, Dave Chinner wrote: > On Thu, Jan 16, 2025 at 03:28:33PM -0800, Darrick J. Wong wrote: > > From: Darrick J. Wong <djwong@xxxxxxxxxx> > > > > Prior to commit 8973af00ec21, in the absence of an explicit > > SOAK_DURATION, this test would run 2500 fsstress operations each of ten > > times through the loop body. On the author's machines, this kept the > > runtime to about 30s total. Oddly, this was changed to 30s per loop > > body with no specific justification in the middle of an fsstress process > > management change. > > I'm pretty sure that was because when you run g/650 on a machine > with 64p, the number of ops performed on the filesystem is > nr_cpus * 2500 * nr_loops. Where does that happen? Oh, heh. -n is the number of ops *per process*. > In that case, each loop was taking over 90s to run, so the overall > runtime was up in the 15-20 minute mark. I wanted to cap the runtime > of each loop to min(nr_ops, SOAK_DURATION) so that it ran in about 5 > minutes in the worst case i.e. (nr_loops * SOAK_DURATION). > > I probably misunderstood how -n nr_ops vs --duration=30 interact; > I expected it to run until either were exhausted, not for duration > to override nr_ops as implied by this: Yeah, SOAK_DURATION overrides pretty much everything. > > On the author's machine, this explodes the runtime from ~30s to 420s. > > Put things back the way they were. > > Yeah, OK, that's exactly waht keep_running() does - duration > overrides nr_ops. > > Ok, so keeping or reverting the change will simply make different > people unhappy because of the excessive runtime the test has at > either ends of the CPU count spectrum - what's the best way to go > about providing the desired min(nr_ops, max loop time) behaviour? > Do we simply cap the maximum process count to keep the number of ops > down to something reasonable (e.g. 16), or something else? How about running fsstress with --duration=3 if SOAK_DURATION isn't set? That should keep the runtime to 30 seconds or so even on larger machines: if [ -n "$SOAK_DURATION" ]; then test "$SOAK_DURATION" -lt 10 && SOAK_DURATION=10 fsstress_args+=(--duration="$((SOAK_DURATION / 10))") else # run for 3s per iteration max for a default runtime of ~30s. fsstress_args+=(--duration=3) fi --D > -Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx >
