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| author | Mika Kuoppala <mika.kuoppala@linux.intel.com> | 2017-01-17 17:59:07 +0200 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2017-01-18 10:47:32 +0000 |
| commit | 71895a085879d7bc490611994c7efb156162f33d (patch) | |
| tree | 9a4f3ab1f189d97b7a20a443ed4f75d1ba2faa76 /drivers | |
| parent | 0e178aef8f13ff11dc9dec82c2cd849981cb1ad1 (diff) | |
| download | linux-stable-71895a085879d7bc490611994c7efb156162f33d.tar.gz linux-stable-71895a085879d7bc490611994c7efb156162f33d.tar.bz2 linux-stable-71895a085879d7bc490611994c7efb156162f33d.zip | |
drm/i915: Add comment how we treat hung contexts
Explain in a comment how and why we treat hung context like we do.
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1484668747-9120-7-git-send-email-mika.kuoppala@intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/gpu/drm/i915/i915_gem.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 3e10e8101014..d6ec63997ca3 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -2697,6 +2697,27 @@ static bool i915_gem_reset_request(struct drm_i915_gem_request *request) /* Read once and return the resolution */ const bool guilty = engine_stalled(request->engine); + /* The guilty request will get skipped on a hung engine. + * + * Users of client default contexts do not rely on logical + * state preserved between batches so it is safe to execute + * queued requests following the hang. Non default contexts + * rely on preserved state, so skipping a batch loses the + * evolution of the state and it needs to be considered corrupted. + * Executing more queued batches on top of corrupted state is + * risky. But we take the risk by trying to advance through + * the queued requests in order to make the client behaviour + * more predictable around resets, by not throwing away random + * amount of batches it has prepared for execution. Sophisticated + * clients can use gem_reset_stats_ioctl and dma fence status + * (exported via sync_file info ioctl on explicit fences) to observe + * when it loses the context state and should rebuild accordingly. + * + * The context ban, and ultimately the client ban, mechanism are safety + * valves if client submission ends up resulting in nothing more than + * subsequent hangs. + */ + if (guilty) { i915_gem_context_mark_guilty(request->ctx); skip_request(request); |