[AMD Official Use Only - Internal Distribution Only]
static void drm_sched_job_timedout(struct work_struct *work)
279 {
280 struct drm_gpu_scheduler *sched;
281 struct drm_sched_job *job;
282
283 sched = container_of(work, struct drm_gpu_scheduler, work_tdr.work);
284
285 /* Protects against concurrent deletion in drm_sched_get_cleanup_job */
286 spin_lock(&sched->job_list_lock);
287 job = list_first_entry_or_null(&sched->ring_mirror_list,
288 struct drm_sched_job, node);
289
290 if (job) {
291 /*
292 * Remove the bad job so it cannot be freed by concurrent
293 * drm_sched_cleanup_jobs. It will be reinserted back after
sched->thread
294 * is parked at which point it's safe.
295 */
296 list_del_init(&job->node);
297 spin_unlock(&sched->job_list_lock);
298
299 job->sched->ops->timedout_job(job);
Thanks
------------------------------------------
Monk Liu | Cloud-GPU Core team
------------------------------------------
From: Liu, Monk
Sent: Friday, February 26, 2021 7:54 PM
To: Koenig, Christian <[email protected]>; [email protected]
Cc: Zhang, Andy <[email protected]>; Chen, Horace <[email protected]>;
Zhang, Jack (Jian) <[email protected]>
Subject: RE: [RFC] a new approach to detect which ring is the real black sheep
upon TDR reported
[AMD Official Use Only - Internal Distribution Only]
See in line
Thanks
------------------------------------------
Monk Liu | Cloud-GPU Core team
------------------------------------------
From: Koenig, Christian
<[email protected]<mailto:[email protected]>>
Sent: Friday, February 26, 2021 3:58 PM
To: Liu, Monk <[email protected]<mailto:[email protected]>>;
[email protected]<mailto:[email protected]>
Cc: Zhang, Andy <[email protected]<mailto:[email protected]>>; Chen, Horace
<[email protected]<mailto:[email protected]>>; Zhang, Jack (Jian)
<[email protected]<mailto:[email protected]>>
Subject: Re: [RFC] a new approach to detect which ring is the real black sheep
upon TDR reported
Hi Monk,
in general an interesting idea, but I see two major problems with that:
1. It would make the reset take much longer.
2. Things get often stuck because of timing issues, so a guilty job might pass
perfectly when run a second time.
[ML] but the innocent ring already reported a TDR, and the drm sched logic
already deleted this "sched_job" in its mirror list, thus you don't have chance
to re-submit it again after reset, that's the major problem here.
Apart from that the whole ring mirror list turned out to be a really bad idea.
E.g. we still struggle with object life time because the concept doesn't fit
into the object model of the GPU scheduler under Linux.
We should probably work on this separately and straighten up the job
destruction once more and keep the recovery information in the fence instead.
[ML] we claim to our customer that no innocent process will be dropped or
cancelled, and our current logic works for the most time, but only when there
are different process running on gfx/computes rings then we would run into the
tricky situation I stated here, and the proposal is the only way I can figure
out so far, do you have a better solution or idea we review it as another
candidate RFC ? Be note that we raised this proposal is because we do hit our
trouble and we do need to resolve it .... So even a not perfect solution is
still better than just cancel the innocent job (and their context/process)
Thanks !
Regards,
Christian.
Am 26.02.21 um 06:58 schrieb Liu, Monk:
[AMD Public Use]
Hi all
NAVI2X project hit a really hard to solve issue now, and it is turned out to
be a general headache of our TDR mechanism , check below scenario:
1. There is a job1 running on compute1 ring at timestamp
2. There is a job2 running on gfx ring at timestamp
3. Job1 is the guilty one, and job1/job2 were scheduled to their rings at
almost the same timestamp
4. After 2 seconds we receive two TDR reporting from both GFX ring and
compute ring
5. Current scheme is that in drm scheduler all the head jobs of those two
rings are considered "bad job" and taken away from the mirror list
6. The result is both the real guilty job (job1) and the innocent job (job2)
were all deleted from mirror list, and their corresponding contexts were also
treated as guilty (so the innocent process remains running is not secured)
But by our wish the ideal case is TDR mechanism can detect which ring is the
guilty ring and the innocent ring can resubmits all its pending jobs:
1. Job1 to be deleted from compute1 ring's mirror list
2. Job2 is kept and resubmitted later and its belonging process/context are
even not aware of this TDR at all
Here I have a proposal tend to achieve above goal and it rough procedure is :
1. Once any ring reports a TDR, the head job is *not* treated as "bad job",
and it is *not* deleted from the mirror list in drm sched functions
2. In vendor's function (our amdgpu driver here):
* reset GPU
* repeat below actions on each RINGS * one by one *:
1. take the head job and submit it on this ring
2. see if it completes, if not then this job is the real "bad job"
3. take it away from mirror list if this head job is "bad job"
* After above iteration on all RINGS, we already clears all the bad
job(s)
1. Resubmit all jobs from each mirror list to their corresponding rings
(this is the existed logic)
The idea of this is to use "serial" way to re-run and re-check each head job of
each RING, in order to take out the real black sheep and its guilty context.
P.S.: we can use this approaches only on GFX/KCQ ring reports TDR , since those
rings are intermutually affected to each other. For SDMA ring timeout it
definitely proves the head job on SDMA ring is really guilty.
Thanks
------------------------------------------
Monk Liu | Cloud-GPU Core team
------------------------------------------
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