> -----Original Message----- > From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Sent: Wednesday, October 2, 2019 7:23 AM > To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx > Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>; Joonas Lahtinen > <joonas.lahtinen@xxxxxxxxxxxxxxx>; Winiarski, Michal > <michal.winiarski@xxxxxxxxx>; Bloomfield, Jon <jon.bloomfield@xxxxxxxxx> > Subject: [PATCH v2] drm/i915: Cancel non-persistent contexts on close > > Normally, we rely on our hangcheck to prevent persistent batches from > hogging the GPU. However, if the user disables hangcheck, this mechanism > breaks down. Despite our insistence that this is unsafe, the users are > equally insistent that they want to use endless batches and will disable > the hangcheck mechanism. We are looking at perhaps replacing hangcheck > with a softer mechanism, that sends a pulse down the engine to check if > it is well. We can use the same preemptive pulse to flush an active > persistent context off the GPU upon context close, preventing resources > being lost and unkillable requests remaining on the GPU after process > termination. To avoid changing the ABI and accidentally breaking > existing userspace, we make the persistence of a context explicit and > enable it by default (matching current ABI). Userspace can opt out of > persistent mode (forcing requests to be cancelled when the context is > closed by process termination or explicitly) by a context parameter. To > facilitate existing use-cases of disabling hangcheck, if the modparam is > disabled (i915.enable_hangcheck=0), we disable persistence mode by > default. (Note, one of the outcomes for supporting endless mode will be > the removal of hangchecking, at which point opting into persistent mode > will be mandatory, or maybe the default perhaps controlled by cgroups.) > > v2: Check for hangchecking at context termination, so that we are not > left with undying contexts from a craft user. s/craft/crafty/ unless we only care about sailors. Otherwise: Reviewed-by: Jon Bloomfield <jon.bloomfield@xxxxxxxxx> _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
