On Sun, 6 Nov 2011 12:31:34 +0100, Daniel Vetter <[email protected]> wrote: > We don't have any read in a fastpath that needs forcewake, so I've > decided to not care much about overhead. > > This prevents tests/gem_hangcheck_forcewake from i-g-t from killing my > snb on recent kernels - something must have slightly changed the > timings.
Almost there. You just haven't explained the rationale for *this* patch, which is that hangcheck needs to acquire the forcewake in order to read the registers and hangcheck must not take the struct_mutex (or else deadlock with wait_request and a hung GPU). So there is a choice here: introduce a new locking rule for forcewake, or use the existing struct_mutex inside hangcheck and therefore drop the mutex for wait_request. The first definitely feels safer than dropping struct_mutex on waits, and I haven't thought of any tangible benefits for doing so (other than concurrent clients might see an improvement). -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
