Messages in this thread | | | Date | Fri, 22 Sep 2023 15:02:30 +0100 | Subject | Re: [PATCH v6 6/6] drm/drm-file: Show finer-grained BO sizes in drm_show_memory_stats | From | Tvrtko Ursulin <> |
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On 22/09/2023 12:03, Adrián Larumbe wrote: > On 21.09.2023 11:14, Tvrtko Ursulin wrote: >> >> On 20/09/2023 16:32, Tvrtko Ursulin wrote: >>> >>> On 20/09/2023 00:34, Adrián Larumbe wrote: >>>> The current implementation will try to pick the highest available size >>>> display unit as soon as the BO size exceeds that of the previous >>>> multiplier. That can lead to loss of precision in contexts of low memory >>>> usage. >>>> >>>> The new selection criteria try to preserve precision, whilst also >>>> increasing the display unit selection threshold to render more accurate >>>> values. >>>> >>>> Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com> >>>> Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> >>>> Reviewed-by: Steven Price <steven.price@arm.com> >>>> --- >>>> drivers/gpu/drm/drm_file.c | 5 ++++- >>>> 1 file changed, 4 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c >>>> index 762965e3d503..34cfa128ffe5 100644 >>>> --- a/drivers/gpu/drm/drm_file.c >>>> +++ b/drivers/gpu/drm/drm_file.c >>>> @@ -872,6 +872,8 @@ void drm_send_event(struct drm_device *dev, struct >>>> drm_pending_event *e) >>>> } >>>> EXPORT_SYMBOL(drm_send_event); >>>> +#define UPPER_UNIT_THRESHOLD 100 >>>> + >>>> static void print_size(struct drm_printer *p, const char *stat, >>>> const char *region, u64 sz) >>>> { >>>> @@ -879,7 +881,8 @@ static void print_size(struct drm_printer *p, >>>> const char *stat, >>>> unsigned u; >>>> for (u = 0; u < ARRAY_SIZE(units) - 1; u++) { >>>> - if (sz < SZ_1K) >>>> + if ((sz & (SZ_1K - 1)) && >>> >>> IS_ALIGNED worth it at all? >>> >>>> + sz < UPPER_UNIT_THRESHOLD * SZ_1K) >>>> break; >>> >>> Excuse me for a late comment (I was away). I did not get what what is >>> special about a ~10% threshold? Sounds to me just going with the lower >>> unit, when size is not aligned to the higher one, would be better than >>> sometimes precision-sometimes-not. >> >> FWIW both current and the threshold option make testing the feature very >> annoying. > > How so?
I have to build in the knowledge of implementation details of print_size() into my IGT in order to use the right size BOs, so test is able to verify stats move as expected. It just feels wrong.
>> So I'd really propose we simply use smaller unit when unaligned. > > Like I said in the previous reply, for drm files whose overall BO size sum is enormous > but not a multiple of a MiB, this would render huge number representations in KiB. > I don't find this particularly comfortable to read, and then this extra precision > would mean nothing to nvtop or gputop, which would have to scale the size to their > available screen dimensions when plotting them.
I don't think numbers in KiB are so huge.
And I don't think people will end up reading them manually a lot anyway, since you have to hunt the pid, and fd, etc.. It is much more realistic that some tool like gputop will be used.
And I don't think consistency of units across drivers or whatever matters. Even better to keep userspace parser on their toes and make then follow drm-usage-stats.rst and not any implementations, at some point in time.
Regards,
Tvrtko
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