Bug 234325 - pmcstat seems to be broken in sampling mode (at least on amd hardware)
Summary: pmcstat seems to be broken in sampling mode (at least on amd hardware)
Status: New
Alias: None
Product: Base System
Classification: Unclassified
Component: bin (show other bugs)
Version: 12.0-RELEASE
Hardware: amd64 Any
: --- Affects Only Me
Assignee: freebsd-bugs mailing list
URL:
Keywords: regression
Depends on:
Blocks:
 
Reported: 2018-12-24 07:41 UTC by shamaz.mazum
Modified: 2018-12-24 18:40 UTC (History)
1 user (show)

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Description shamaz.mazum 2018-12-24 07:41:50 UTC
Hello. I use FreeBSD 12.0-RELEASE on two machines (one with Ryzen 5 1600X processor and the other with FX-6300).

Recently (presumable after upgrading to 12.0-RELEASE) pmcstat stopped working in sample mode.

I run it as:
`pmcstat -P instructions -O test.out -n 65536 ./noisecpu` on FX-6300
or
`pmcstat -P ex_ret_instr -O test.out -n 65536 ./noisecpu` on Ryzen

and then I run `pmcstat -R test.out -g`

In both cases it creates directories (e.g. ex_ret_instr) which are either empty or containing only kernel.gmon

`noisecpu` is computation heavy program, calculating value noise on a large grid and works for ~8 seconds.

Conversion statistics usually looks like following:
#exec/elf 1
#samples/total 169
#samples/unclaimed 165
#callchain/dubious-frames 165

In counting mode (with -p argument) everything seems to be working. Can anybody confirm this?