[Mesa-dev] [PATCH] etnaviv: only flush resource to self if no scanout buffer exists

[Christian Gmeiner]

2017-06-26 13:30 GMT+02:00 Lucas Stach <l.stach at pengutronix.de>:
> Am Montag, den 26.06.2017, 13:09 +0200 schrieb Christian Gmeiner:
>> 2017-06-26 12:25 GMT+02:00 Lucas Stach <l.stach at pengutronix.de>:
>> > Currently a resource flush may trigger a self resolve, even if a
>> > scanout buffer
>> > exists, but is up to date. If a scanout buffer exists we only ever
>> > want to
>> > flush the resource to the scanout buffer. This fixes a performance
>> > regression.
>> >
>> > Fixes: dda956340ce9 (etnaviv: resolve tile status when flushing
>> > resource)
>> > Cc: mesa-stable at lists.freedesktop.org
>> > Signed-off-by: Lucas Stach <l.stach at pengutronix.de>

Reviewed-by: Christian Gmeiner <christian.gmeiner at gmail.com>

>> > ---
>> >  src/gallium/drivers/etnaviv/etnaviv_clear_blit.c | 9 +++++----
>> >  1 file changed, 5 insertions(+), 4 deletions(-)
>> >
>> > diff --git a/src/gallium/drivers/etnaviv/etnaviv_clear_blit.c
>> > b/src/gallium/drivers/etnaviv/etnaviv_clear_blit.c
>> > index e4620a3015e9..80967be3f93d 100644
>> > --- a/src/gallium/drivers/etnaviv/etnaviv_clear_blit.c
>> > +++ b/src/gallium/drivers/etnaviv/etnaviv_clear_blit.c
>> > @@ -602,10 +602,11 @@ etna_flush_resource(struct pipe_context
>> > *pctx, struct pipe_resource *prsc)
>> >  {
>> >     struct etna_resource *rsc = etna_resource(prsc);
>> >
>> > -   if (rsc->scanout &&
>> > -       etna_resource_older(etna_resource(rsc->scanout->prime),
>> > rsc)) {
>> > -      etna_copy_resource(pctx, rsc->scanout->prime, prsc, 0, 0);
>> > -      etna_resource(rsc->scanout->prime)->seqno = rsc->seqno;
>> > +   if (rsc->scanout) {
>> > +      if (etna_resource_older(etna_resource(rsc->scanout->prime),
>> > rsc)) {
>> > +         etna_copy_resource(pctx, rsc->scanout->prime, prsc, 0,
>> > 0);
>> > +         etna_resource(rsc->scanout->prime)->seqno = rsc->seqno;
>> > +      }
>> >     } else if (etna_resource_needs_flush(rsc)) {
>> >        etna_copy_resource(pctx, prsc, prsc, 0, 0);
>> >        rsc->flush_seqno = rsc->seqno;
>>
>> Maybe I am running out of coffee but I do not see the logical change
>> here that
>> should fix a performance regression.
>>
>> before:
>> if (x && y) {
>>    do_stuff
>> } else if (...) {
>>   ..
>> }
>
> The change is that we only ever want to enter the else if path if x ==
> false. Currently we can also hit the else if path if x == true and y ==
> false.
>

Thanks - got it now.

greets
--
Christian Gmeiner, MSc

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