Messages in this thread | | | Subject | Re: [PATCH 1/2] drm/i915: Break busywaiting for requests on pending signals | From | Tvrtko Ursulin <> | Date | Mon, 16 Nov 2015 11:40:25 +0000 |
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On 16/11/15 11:22, Chris Wilson wrote: > On Mon, Nov 16, 2015 at 09:54:10AM +0000, Tvrtko Ursulin wrote: >> >> Hi, >> >> On 15/11/15 13:32, Chris Wilson wrote: >>> The busywait in __i915_spin_request() does not respect pending signals >>> and so may consume the entire timeslice for the task instead of >>> returning to userspace to handle the signal. >> >> Obviously correct to break the spin, but if spending a jiffie to >> react to signals was the only problem then it is not too severe. >> >> Add something to the commit message about how it was found/reported >> and about the severity of impact, etc? > > Perhaps: > > At the worst case this could cause a delay in signal processing of 20ms, > which would be a noticeable jitter in cursor tracking. If a higher > resolution signal was being used, for example to provide fairness of a > server timeslices between clients, we could expect to detect some > unfairness between clients. This issue was noticed when inspecting a > report of poor interactivity resulting from excessively high > __i915_spin_request usage.
Oh its the Xorg scheduler tick... I always forget about that. Was thinking that it is only about fatal, or at least infrequent signals.
Regards,
Tvrtko
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