Quoting Shi, Yang A (2020-10-16 02:08:24) > Hi Chris: > > How to determine the length of the magic delay in here? That is the question. I started with a large udelay, played with moving it around and shortening (5us) to try and isolate what is going on. An arbitrary delay is awful as it is guaranteed to fail since it imposes no barrier/serialisation, mmio often have the desired side-effect, if you can tickle the right one. Still this is nothing more than empirical evidence (an easily reproduced hang that goes away), and not a hard explanation. An uncached read upon acking the preemption event, is a pretty nasty nuisance (it's 80% of our CS bottom half) but as compromises go, it could be far worse. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
