Quoting Tvrtko Ursulin (2018-02-19 09:25:00) > > On 16/02/2018 10:13, Chris Wilson wrote: > > Afaict, it's complaining that because the writer is special the reader > > needs irq protection. Which I don't understand, as the point is that the > > writer can run concurrently to the readers (the readers have to > > restart). What am I missing? > > As discussed on IRC, issue is courtesy of perf read callback running in > hardirq context, that the reader can interrupt the writer and so > incorrectly declare a stable sequence number while reading the mixed up > version of the underlying data. > > Writer: > seqno++ > modify some fields > <Reader IRQ... > read seqno > read fields > re-read seqno -> OK > >..Reader IRQ > modify other fields > seqno++ > > So we need to go back to the first, irqsave version. Do you want to > pursue this change right now or leave it for some future work? It's a small optimisation (hopefully ;) so pursue at leisure or in the context of wider work. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
