On Fri, Sep 13, 2013 at 2:59 AM, Rob Clark <robdcl...@gmail.com> wrote: > I guess in i915 (and ttm) case, the issue arises due to need for CPU > access to buffer via GTT? In which case I should be safe to drop the > set_need_resched() as well? (Since CPU always has direct access to the > pages.) Or am I missing something about the original issue that > necessitated set_need_resched()?
For drm/i915 the _only_ reason we've had it was to avoid life-locking with our gpu reset work when the gpu hung. We've fixed that properly now by using a wait-queue to stall when a gpu reset is pending and proper locking in the gpu reset handler (plus tons of evil tests to make sure it doesn't break, there's rather fragile lock-dropping and tricky ordering involved). So if you don't have i915's broken gpu reset handling from yonder you don't need our cargo-cult. ttm's usage with a trylock+yield is a different form of duct-tape to paper over locking inversions between copy_*_user callsites and the pagefault handler. In any case there's no way it actually works properly ;-) Cheers, Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
