Re: [PATCH v2] perf test: Add AMD IBS sw filter test

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Sat, May 24, 2025 at 03:17:13PM +0530, Ravi Bangoria wrote:
> Hi Namhyung,
> 
> On 24-May-25 5:57 AM, Namhyung Kim wrote:
> > The kernel v6.14 added 'swfilt' to support privilege filtering in
> > software so that IBS can be used by regular users.  Add a test case in
> > x86 to verify the behavior.
> > 
> >   $ sudo perf test -vv 'IBS software filter'
> >   113: AMD IBS software filtering:
> >   --- start ---
> >   test child forked, pid 178826
> >   check availability of IBS swfilt
> >   run perf record with modifier and swfilt
> >   [ perf record: Woken up 3 times to write data ]
> >   [ perf record: Captured and wrote 0.000 MB /dev/null ]
> >   [ perf record: Woken up 3 times to write data ]
> >   [ perf record: Captured and wrote 0.000 MB /dev/null ]
> >   [ perf record: Woken up 3 times to write data ]
> >   [ perf record: Captured and wrote 0.000 MB /dev/null ]
> >   [ perf record: Woken up 0 times to write data ]
> >   [ perf record: Captured and wrote 0.000 MB /dev/null ]
> >   check number of samples with swfilt
> >   [ perf record: Woken up 3 times to write data ]
> >   [ perf record: Captured and wrote 0.037 MB - ]
> >   [ perf record: Woken up 3 times to write data ]
> >   [ perf record: Captured and wrote 0.041 MB - ]
> >   ---- end(0) ----
> >   113: AMD IBS software filtering                                      : Ok
> > 
> > Cc: Ravi Bangoria <ravi.bangoria@amd.com>
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> 
> Reviewed-by: Ravi Bangoria <ravi.bangoria@amd.com>
> 
> A minor nit below ...
> 
> > +echo "check number of samples with swfilt"
> > +
> > +kernel_sample=$(perf record -e ibs_op/swfilt/u -o- true | perf script -i- -F misc | grep -c ^K)
> 
> "true" barely runs in userspace. So, many a times this "perf record"
> generates no samples :)

Right, something else, maybe one of those workloads:

acme@number:~/git/perf-tools-next$ perf test --list-workloads
noploop
thloop
leafloop
sqrtloop
brstack
datasym
landlock
acme@number:~/git/perf-tools-next$

root@number:~# time perf record -e ibs_op/swfilt/u perf test -w sqrtloop
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.160 MB perf.data (3976 samples) ]

real	0m1.588s
user	0m1.407s
sys	0m0.161s
root@number:~# perf script | wc -l
3976
root@number:~#

But I'm applying the patch as is, we can replace the workload later.

- Arnaldo