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
