Bugzilla – Attachment 1374 Details for
Bug 27032
[Hygon] [devel-6.6] [Bugfix] Fix memory bandwidth counter width for Hygon QoS
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Memory bandwidth counter width and overflow issue - steps to reproduce
Memory bandwidth counter width and overflow issue - steps to reproduce.txt (text/plain), 3.62 KB, created by
shenxiaochen
on 2025-11-13 13:35:11 UTC
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Description:
Memory bandwidth counter width and overflow issue - steps to reproduce
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Creator:
shenxiaochen
Created:
2025-11-13 13:35:11 UTC
Size:
3.62 KB
patch
obsolete
>Memory bandwidth counter width and overflow issue - steps to reproduce: > >1. Run memory bandwidth stress workload (e.g., STREAM) on multiple CPUs to generate memory bandwidth. > ># taskset -c 0-7 ./stream_c.exe ># pstree -lp | grep stream_c.exe > | |-sshd(4118)---bash(4184)---stream_c.exe(4388)-+-{stream_c.exe}(4389) > | | |-{stream_c.exe}(4390) > | | |-{stream_c.exe}(4391) > | | |-{stream_c.exe}(4392) > | | |-{stream_c.exe}(4393) > | | |-{stream_c.exe}(4394) > | | `-{stream_c.exe}(4395) > > >2. Mount Resctrl Filesystem, create control group "p1", add STREAM workload PIDs/TIDs to p1 group: > ># mount -t resctrl resctrl /sys/fs/resctrl ># mkdir /sys/fs/resctrl/p1 ># ./add_tasks.sh >------------------------------------------------------------------------------------- >#/usr/bin/bash ># add_tasks.sh > >ID=`ps -efL | grep stream_c.exe | grep -v "grep" | awk '{print $4}'` >for id in $ID >do > echo $id >/sys/fs/resctrl/p1/tasks >done >------------------------------------------------------------------------------------- > > >3. Read memory bandwidth counters with 1 second interval, observe the random unexpected values due to incorrect counter overflow handling: > ># ./mbm_total_verbose.sh >------------------------------------------------------------------------------------- >#/usr/bin/bash ># mbm_total_verbose.sh > >total_1=`cat /sys/fs/resctrl/p1/mon_data/mon_L3_00/mbm_total_bytes` >sleep 1 >while true >do > total_2=`cat /sys/fs/resctrl/p1/mon_data/mon_L3_00/mbm_total_bytes` > echo "total b/w (bytes/s):" `expr $total_2 - $total_1` "($total_2 - $total_1)" > total_1=$total_2 > sleep 1 >done >------------------------------------------------------------------------------------- > >total b/w (bytes/s): 21663042304 (222340959424 - 200677917120) >total b/w (bytes/s): 21951040640 (244292000064 - 222340959424) >total b/w (bytes/s): 21491510336 (265783510400 - 244292000064) >total b/w (bytes/s): 1125646660758656 (1125912444269056 - 265783510400) < == unexpected values due to incorrect counter overflow handling >total b/w (bytes/s): 21957204096 (1125934401473152 - 1125912444269056) >total b/w (bytes/s): 21750773184 (1125956152246336 - 1125934401473152) >total b/w (bytes/s): 21397818496 (1125977550064832 - 1125956152246336) >total b/w (bytes/s): 21933403264 (1125999483468096 - 1125977550064832) >total b/w (bytes/s): 21947796032 (1126021431264128 - 1125999483468096) >total b/w (bytes/s): 21271977152 (1126042703241280 - 1126021431264128) >total b/w (bytes/s): 21854536000 (1126064557777280 - 1126042703241280) >total b/w (bytes/s): 21957381568 (1126086515158848 - 1126064557777280) >total b/w (bytes/s): 21358693184 (1126107873852032 - 1126086515158848) >total b/w (bytes/s): 21771448640 (1126129645300672 - 1126107873852032) >total b/w (bytes/s): 21960641920 (1126151605942592 - 1126129645300672) >total b/w (bytes/s): 21463460352 (1126173069402944 - 1126151605942592) >total b/w (bytes/s): 1125646683192192 (2251819752595136 - 1126173069402944) < == unexpected values due to incorrect counter overflow handling >total b/w (bytes/s): 21958503872 (2251841711099008 - 2251819752595136) >total b/w (bytes/s): 21731181440 (2251863442280448 - 2251841711099008) >total b/w (bytes/s): 21410335936 (2251884852616384 - 2251863442280448)
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