Quoting Antonio Argenziano (2018-03-09 19:15:45) > > > On 08/03/18 17:03, Chris Wilson wrote: > > Quoting Antonio Argenziano (2018-03-09 00:45:42) > >> > >> > >> On 08/03/18 09:13, Chris Wilson wrote: > >>> Exercise some new API that allows applications to request that > >>> individual contexts are executed within a desired frequency range. > >>> > >>> v2: Split single/continuous set_freq subtests > >>> > >>> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > >>> Cc: Paneri, Praveen <praveen.paneri@xxxxxxxxx> > >>> Cc: Kamble, Sagar A <sagar.a.kamble@xxxxxxxxx> > >>> Cc: Antonio Argenziano <antonio.argenziano@xxxxxxxxx> > >>> --- > >>> tests/Makefile.am | 1 + > >>> tests/Makefile.sources | 1 + > >>> tests/gem_ctx_freq.c | 604 +++++++++++++++++++++++++++++++++++++++++++++++++ > >>> tests/meson.build | 1 + > >>> 4 files changed, 607 insertions(+) > >>> create mode 100644 tests/gem_ctx_freq.c > >>> > >> > > >>> + uint32_t cur, discard; > >>> + > >>> + set_freq(fd, ctx, freq, freq); > >>> + get_freq(fd, ctx, &cur, &discard); > >> > >> igt_assert_eq(freq, cur)? > > > > Not quite. The trick is that the interface is not strictly idempotent, > > since we pass in MHz, the driver converts that into freq bins and spits > > it back out to the nearest MHz. So cur is not strictly freq, it just > > happens that 50MHz is the bin size on gen9. > > > > The idea here is that we grab the adjusted freq from the driver to > > validate with. > > I see, can we enforce a tolerance? It feels like we are trusting the > kernel too much, but if that is the only thing we can do... for (i = min; i <= max; i++) igt_assert(min <= set_and_fetch_freq(i) <= max); I don't think we want to constrain the ABI any more than that. But adding that level of check seems ok. The behaviour is we ask the kernel for a range, the kernel tells us what range it can provide based on the request. Then we expect that the kernel upholds that contract. (Except where we make a conflicting contract with another party, either parallel execution or sysadmin override.) Binding ourselves into a tighter contract feels overly prescriptive and not flexible enough to weasel our way out of bad situations in future. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
