On Wed, Jun 12, 2013 at 6:56 AM, Jerome Glisse <j.glisse@xxxxxxxxx> wrote: > On Wed, Jun 12, 2013 at 6:26 AM, Michel Dänzer <michel@xxxxxxxxxxx> wrote: >> On Die, 2013-06-11 at 16:23 -0700, Andy Lutomirski wrote: >>> If the device is idle for over ten seconds, then the next attempt to do >>> anything can race with the lockup detector and cause a bogus lockup >>> to be detected. >>> >>> Oddly, the situation is well-described in the lockup detector's comments >>> and a fix is even described. This patch implements that fix (and corrects >>> some typos in the description). >>> >>> My system has been stable for about a week running this code. Without this, >>> my screen would go blank every now and then and, when it came back, everything >>> would be remarkably slow (the latter is a separate bug). >>> >>> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx> >> >> [...] >> >>> diff --git a/drivers/gpu/drm/radeon/radeon_ring.c b/drivers/gpu/drm/radeon/radeon_ring.c >>> index 1ef5eaa..fb7b3ea 100644 >>> --- a/drivers/gpu/drm/radeon/radeon_ring.c >>> +++ b/drivers/gpu/drm/radeon/radeon_ring.c >>> @@ -547,12 +547,12 @@ void radeon_ring_lockup_update(struct radeon_ring *ring) >>> * have CP rptr to a different value of jiffies wrap around which will force >>> * initialization of the lockup tracking informations. >>> * >>> - * A possible false positivie is if we get call after while and last_cp_rptr == >>> - * the current CP rptr, even if it's unlikely it might happen. To avoid this >>> - * if the elapsed time since last call is bigger than 2 second than we return >>> - * false and update the tracking information. Due to this the caller must call >>> - * radeon_ring_test_lockup several time in less than 2sec for lockup to be reported >>> - * the fencing code should be cautious about that. >>> + * A possible false positive is if we get called after a while and >>> + * last_cp_rptr == the current CP rptr, even if it's unlikely it might >>> + * happen. To avoid this if the elapsed time since the last call is bigger >>> + * than 2 second then we return false and update the tracking >>> + * information. Due to this the caller must call radeon_ring_test_lockup >>> + * more frequently than once every 2s when waiting. >> >> Is it guaranteed that radeon_ring_test_lockup will be called more often >> than every 2s when waiting? If not, this change might prevent a real >> lockup from being detected? > > Yes it will if you wait for a fence, because the fence timeout wait is > way smaller than 2sec so radeon_ring_is_lockup get call several time, > which call radeon_ring_force_activity and then > radeon_ring_test_lockup. > > This also means it very very very unlikely (see below for the likely > case) to have a wrap around that give last rptr same as current one. > > The likely case is when you have something like a long compute, then > nothing is lockup but you keep filling ring with > radeon_ring_force_activity but the cp is still stuck on the ib of the > compute stuff so rptr does not progress. > >> Either way, I wonder if there might not be a simpler solution to the >> problem, e.g. by updating last_activity when submitting commands to a >> previously empty ring. > > Maybe but i still don't think it should matter. > > Andy can you test (without your patch) and see if it helps with your issue : > http://people.freedesktop.org/~glisse/0001-drm-radeon-update-lockup-tracking-when-scheduling-in.patch Testing now. I'll report back in a couple of days. I don't think that long computes have anything to do with it. The bogus lockups happen when I look away from my computer for a while and then click something. I thing the graphics are usually completely idle when this happens. AFAIK I've never run an OpenCL or similar application on this system. --Andy _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
