Re: [kvm-unit-tests PATCH v2 0/2] s390x: Add exit time test

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Thu,  1 Sep 2022 17:09:54 +0200
Nico Boehr <nrb@linux.ibm.com> wrote:

> v1->v2:
> ---
> * add missing cc clobber, fix constraints for get_clock_us() (thanks
>   Thomas)
> * avoid array and use pointer to const char* (thanks Thomas)
> * add comment why testing nop makes sense (thanks Thomas)
> * rework constraints and clobbers (thanks Thomas)
> 
> Sometimes, it is useful to measure the exit time of certain instructions
> to e.g. identify performance regressions in instructions emulated by the
> hypervisor.
> 
> This series adds a test which executes some instructions and measures
> their execution time. Since their execution time depends a lot on the
> environment at hand, all tests are reported as PASS currently.
> 
> The point of this series is not so much the instructions which have been
> chosen here (but your ideas are welcome), but rather the general
> question whether it makes sense to have a test like this in
> kvm-unit-tests.

perhaps it makes sense to merge this patch series with your other one,
"s390x: Add migration test for guest TOD clock"

they both concern timing and reshuffling around and/or fixing timing
functions

> 
> Nico Boehr (2):
>   lib/s390x: time: add wrapper for stckf
>   s390x: add exittime tests
> 
>  lib/s390x/asm/time.h |  11 +-
>  s390x/Makefile       |   1 +
>  s390x/exittime.c     | 255 +++++++++++++++++++++++++++++++++++++++++++
>  s390x/unittests.cfg  |   4 +
>  4 files changed, 270 insertions(+), 1 deletion(-)
>  create mode 100644 s390x/exittime.c
>