On Thu 05-06-25 08:48:07, Baolin Wang wrote: > > > On 2025/6/5 00:54, Shakeel Butt wrote: > > On Wed, Jun 04, 2025 at 10:16:18PM +0800, Baolin Wang wrote: > > > > > > > > > On 2025/6/4 21:46, Vlastimil Babka wrote: > > > > On 6/4/25 14:46, Baolin Wang wrote: > > > > > > Baolin, please run stress-ng command that stresses minor anon page > > > > > > faults in multiple threads and then run multiple bash scripts which cat > > > > > > /proc/pidof(stress-ng)/status. That should be how much the stress-ng > > > > > > process is impacted by the parallel status readers versus without them. > > > > > > > > > > Sure. Thanks Shakeel. I run the stress-ng with the 'stress-ng --fault 32 > > > > > --perf -t 1m' command, while simultaneously running the following > > > > > scripts to read the /proc/pidof(stress-ng)/status for each thread. > > > > > > > > How many of those scripts? > > > > > > 1 script, but will start 32 threads to read each stress-ng thread's status > > > interface. > > > > > > > > From the following data, I did not observe any obvious impact of this > > > > > patch on the stress-ng tests when repeatedly reading the > > > > > /proc/pidof(stress-ng)/status. > > > > > > > > > > w/o patch > > > > > stress-ng: info: [6891] 3,993,235,331,584 CPU Cycles > > > > > 59.767 B/sec > > > > > stress-ng: info: [6891] 1,472,101,565,760 Instructions > > > > > 22.033 B/sec (0.369 instr. per cycle) > > > > > stress-ng: info: [6891] 36,287,456 Page Faults Total > > > > > 0.543 M/sec > > > > > stress-ng: info: [6891] 36,287,456 Page Faults Minor > > > > > 0.543 M/sec > > > > > > > > > > w/ patch > > > > > stress-ng: info: [6872] 4,018,592,975,968 CPU Cycles > > > > > 60.177 B/sec > > > > > stress-ng: info: [6872] 1,484,856,150,976 Instructions > > > > > 22.235 B/sec (0.369 instr. per cycle) > > > > > stress-ng: info: [6872] 36,547,456 Page Faults Total > > > > > 0.547 M/sec > > > > > stress-ng: info: [6872] 36,547,456 Page Faults Minor > > > > > 0.547 M/sec > > > > > > > > > > ========================= > > > > > #!/bin/bash > > > > > > > > > > # Get the PIDs of stress-ng processes > > > > > PIDS=$(pgrep stress-ng) > > > > > > > > > > # Loop through each PID and monitor /proc/[pid]/status > > > > > for PID in $PIDS; do > > > > > while true; do > > > > > cat /proc/$PID/status > > > > > usleep 100000 > > > > > > > > Hm but this limits the reading to 10 per second? If we want to simulate an > > > > adversary process, it should be without the sleeps I think? > > > > > > OK. I drop the usleep, and I still can not see obvious impact. > > > > > > w/o patch: > > > stress-ng: info: [6848] 4,399,219,085,152 CPU Cycles > > > 67.327 B/sec > > > stress-ng: info: [6848] 1,616,524,844,832 Instructions > > > 24.740 B/sec (0.367 instr. per cycle) > > > stress-ng: info: [6848] 39,529,792 Page Faults Total > > > 0.605 M/sec > > > stress-ng: info: [6848] 39,529,792 Page Faults Minor > > > 0.605 M/sec > > > > > > w/patch: > > > stress-ng: info: [2485] 4,462,440,381,856 CPU Cycles > > > 68.382 B/sec > > > stress-ng: info: [2485] 1,615,101,503,296 Instructions > > > 24.750 B/sec (0.362 instr. per cycle) > > > stress-ng: info: [2485] 39,439,232 Page Faults Total > > > 0.604 M/sec > > > stress-ng: info: [2485] 39,439,232 Page Faults Minor > > > 0.604 M/sec > > > > Is the above with 32 non-sleeping parallel reader scripts? > > Yes. Thanks, this seems much more representative. Please update the changelog with this. With that feel free to add Acked-by: Michal Hocko <mhocko@xxxxxxxx> Thanks! -- Michal Hocko SUSE Labs
