If the kernel couldn't allocate memory because we reached the maximum
number of chunks but no render passes are in flight
(panthor_heap_grow() returning -ENOMEM), we should defer the OOM
handling to the FW by returning a NULL chunk. The FW will then call
the tiler OOM exception handler, which is supposed to implement
incremental rendering (execute an intermediate fragment job to flush
the pending primitives, release the tiler memory that was used to
store those primitives, and start over from where it stopped).
Instead of checking for both ENOMEM and EBUSY, make panthor_heap_grow()
return ENOMEM no matter the reason of this allocation failure, the FW
doesn't care anyway.
v3:
- Add R-bs
v2:
- Make panthor_heap_grow() return -ENOMEM for all kind of allocation
failures
- Document the panthor_heap_grow() semantics
Fixes: de85488138 ("drm/panthor: Add the scheduler logical block")
Signed-off-by: Antonino Maniscalco <antonino.maniscalco@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240502165158.1458959-2-boris.brezillon@collabora.com
This is the piece of software interacting with the FW scheduler, and
taking care of some scheduling aspects when the FW comes short of slots
scheduling slots. Indeed, the FW only expose a few slots, and the kernel
has to give all submission contexts, a chance to execute their jobs.
The kernel-side scheduler is timeslice-based, with a round-robin queue
per priority level.
Job submission is handled with a 1:1 drm_sched_entity:drm_gpu_scheduler,
allowing us to delegate the dependency tracking to the core.
All the gory details should be documented inline.
v6:
- Add Maxime's and Heiko's acks
- Make sure the scheduler is initialized before queueing the tick work
in the MMU fault handler
- Keep header inclusion alphabetically ordered
v5:
- Fix typos
- Call panthor_kernel_bo_destroy(group->syncobjs) unconditionally
- Don't move the group to the waiting list tail when it was already
waiting for a different syncobj
- Fix fatal_queues flagging in the tiler OOM path
- Don't warn when more than one job timesout on a group
- Add a warning message when we fail to allocate a heap chunk
- Add Steve's R-b
v4:
- Check drmm_mutex_init() return code
- s/drm_gem_vmap_unlocked/drm_gem_vunmap_unlocked/ in
panthor_queue_put_syncwait_obj()
- Drop unneeded WARN_ON() in cs_slot_sync_queue_state_locked()
- Use atomic_xchg() instead of atomic_fetch_and(0)
- Fix typos
- Let panthor_kernel_bo_destroy() check for IS_ERR_OR_NULL() BOs
- Defer TILER_OOM event handling to a separate workqueue to prevent
deadlocks when the heap chunk allocation is blocked on mem-reclaim.
This is just a temporary solution, until we add support for
non-blocking/failable allocations
- Pass the scheduler workqueue to drm_sched instead of instantiating
a separate one (no longer needed now that heap chunk allocation
happens on a dedicated wq)
- Set WQ_MEM_RECLAIM on the scheduler workqueue, so we can handle
job timeouts when the system is under mem pressure, and hopefully
free up some memory retained by these jobs
v3:
- Rework the FW event handling logic to avoid races
- Make sure MMU faults kill the group immediately
- Use the panthor_kernel_bo abstraction for group/queue buffers
- Make in_progress an atomic_t, so we can check it without the reset lock
held
- Don't limit the number of groups per context to the FW scheduler
capacity. Fix the limit to 128 for now.
- Add a panthor_job_vm() helper
- Account for panthor_vm changes
- Add our job fence as DMA_RESV_USAGE_WRITE to all external objects
(was previously DMA_RESV_USAGE_BOOKKEEP). I don't get why, given
we're supposed to be fully-explicit, but other drivers do that, so
there must be a good reason
- Account for drm_sched changes
- Provide a panthor_queue_put_syncwait_obj()
- Unconditionally return groups to their idle list in
panthor_sched_suspend()
- Condition of sched_queue_{,delayed_}work fixed to be only when a reset
isn't pending or in progress.
- Several typos in comments fixed.
Co-developed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240229162230.2634044-11-boris.brezillon@collabora.com
