From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 2458717BB6 for ; Mon, 10 Feb 2025 13:43:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739195013; cv=none; b=o4jakDqWBgpl0n5CSfgXxYyC3Pp03sc1aR1eFKyp6/WJcsYaO7iFA4wzNQ2teSl/rikWj8yWnIp+9QDLd9IKA+1Ua2II6RlJKMaxc6aujyjeO9atuSrs8ib/a3SWm+lVdsx1TjhNVtSTTRfThqcLlBZlZoENunlj2Neo4uGwJQs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739195013; c=relaxed/simple; bh=B9RcPANSN+ctBiEjVkkRMrzvUOf3OkkUxX1JyFg5IZ0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=I8pLazeTOF9F4KSIFza4+tTnZCQzi7u0Q7bHJgrV/diyFUqx2jKg9juPynT57AQ5KegIQoNyOYAE4f2jEpe3yejoKGRmBf8FRTMya9ffrY9b8elsWdQic0MStzx9dZZfAdtlQ1iWfiTGGNnrI0jSX8GL18kk8hkYTjspCngvu1w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DC0261BA8 for ; Mon, 10 Feb 2025 05:43:51 -0800 (PST) Received: from e110455-lin.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D64EA3F58B for ; Mon, 10 Feb 2025 05:43:29 -0800 (PST) Date: Mon, 10 Feb 2025 13:43:17 +0000 From: Liviu Dudau To: Boris Brezillon Cc: =?utf-8?Q?Adri=C3=A1n?= Larumbe , Steven Price , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Mihail Atanassov , kernel@collabora.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] drm/panthor: Avoid sleep locking in the internal BO size path Message-ID: References: <20250210124203.124191-1-adrian.larumbe@collabora.com> <20250210124203.124191-2-adrian.larumbe@collabora.com> <20250210141807.064ccacf@collabora.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250210141807.064ccacf@collabora.com> On Mon, Feb 10, 2025 at 02:18:07PM +0100, Boris Brezillon wrote: > On Mon, 10 Feb 2025 12:42:00 +0000 > Adrián Larumbe wrote: > > > A previous commit dealt with a similar situation, whereby upon enabling > > some mutex debug features, a warning about sleep muteces being used in a > > ^ mutexes > > > /proc file read atomic context was being triggered. > > > > Because in this case replacing the heap mutex with a spinlock isn't > > feasible, the fdinfo handler no longer traverses the list of heaps for > > every single VM associated with an open DRM file. Instad, when a new heap > > chunk is allocated, its size is accumulated into a VM-wide tally, which > > also makes the atomic context code path somewhat faster. > > > > Signed-off-by: Adrián Larumbe > > Fixes: 3e2c8c718567 ("drm/panthor: Expose size of driver internal BO's over fdinfo") > > --- > > drivers/gpu/drm/panthor/panthor_heap.c | 38 ++++++++------------------ > > drivers/gpu/drm/panthor/panthor_heap.h | 2 -- > > drivers/gpu/drm/panthor/panthor_mmu.c | 18 +++++++----- > > drivers/gpu/drm/panthor/panthor_mmu.h | 1 + > > 4 files changed, 23 insertions(+), 36 deletions(-) > > > > diff --git a/drivers/gpu/drm/panthor/panthor_heap.c b/drivers/gpu/drm/panthor/panthor_heap.c > > index db0285ce5812..686f209f5b09 100644 > > --- a/drivers/gpu/drm/panthor/panthor_heap.c > > +++ b/drivers/gpu/drm/panthor/panthor_heap.c > > @@ -127,6 +127,8 @@ static void panthor_free_heap_chunk(struct panthor_vm *vm, > > heap->chunk_count--; > > mutex_unlock(&heap->lock); > > > > + panthor_vm_heaps_accumulate(vm, -heap->chunk_size); > > + > > panthor_kernel_bo_destroy(chunk->bo); > > kfree(chunk); > > } > > @@ -180,6 +182,8 @@ static int panthor_alloc_heap_chunk(struct panthor_device *ptdev, > > heap->chunk_count++; > > mutex_unlock(&heap->lock); > > > > + panthor_vm_heaps_accumulate(vm, heap->chunk_size); > > + > > return 0; > > > > err_destroy_bo: > > @@ -389,6 +393,7 @@ int panthor_heap_return_chunk(struct panthor_heap_pool *pool, > > removed = chunk; > > list_del(&chunk->node); > > heap->chunk_count--; > > + panthor_vm_heaps_accumulate(chunk->bo->vm, -heap->chunk_size); > > break; > > } > > } > > @@ -560,6 +565,8 @@ panthor_heap_pool_create(struct panthor_device *ptdev, struct panthor_vm *vm) > > if (ret) > > goto err_destroy_pool; > > > > + panthor_vm_heaps_accumulate(vm, pool->gpu_contexts->obj->size); > > + > > return pool; > > > > err_destroy_pool: > > @@ -594,8 +601,11 @@ void panthor_heap_pool_destroy(struct panthor_heap_pool *pool) > > xa_for_each(&pool->xa, i, heap) > > drm_WARN_ON(&pool->ptdev->base, panthor_heap_destroy_locked(pool, i)); > > > > - if (!IS_ERR_OR_NULL(pool->gpu_contexts)) > > + if (!IS_ERR_OR_NULL(pool->gpu_contexts)) { > > + panthor_vm_heaps_accumulate(pool->gpu_contexts->vm, > > + -pool->gpu_contexts->obj->size); > > panthor_kernel_bo_destroy(pool->gpu_contexts); > > + } > > > > /* Reflects the fact the pool has been destroyed. */ > > pool->vm = NULL; > > @@ -603,29 +613,3 @@ void panthor_heap_pool_destroy(struct panthor_heap_pool *pool) > > > > panthor_heap_pool_put(pool); > > } > > - > > -/** > > - * panthor_heap_pool_size() - Calculate size of all chunks across all heaps in a pool > > - * @pool: Pool whose total chunk size to calculate. > > - * > > - * This function adds the size of all heap chunks across all heaps in the > > - * argument pool. It also adds the size of the gpu contexts kernel bo. > > - * It is meant to be used by fdinfo for displaying the size of internal > > - * driver BO's that aren't exposed to userspace through a GEM handle. > > - * > > - */ > > -size_t panthor_heap_pool_size(struct panthor_heap_pool *pool) > > -{ > > - struct panthor_heap *heap; > > - unsigned long i; > > - size_t size = 0; > > - > > - down_read(&pool->lock); > > - xa_for_each(&pool->xa, i, heap) > > - size += heap->chunk_size * heap->chunk_count; > > - up_read(&pool->lock); > > - > > - size += pool->gpu_contexts->obj->size; > > - > > - return size; > > -} > > diff --git a/drivers/gpu/drm/panthor/panthor_heap.h b/drivers/gpu/drm/panthor/panthor_heap.h > > index e3358d4e8edb..25a5f2bba445 100644 > > --- a/drivers/gpu/drm/panthor/panthor_heap.h > > +++ b/drivers/gpu/drm/panthor/panthor_heap.h > > @@ -27,8 +27,6 @@ struct panthor_heap_pool * > > panthor_heap_pool_get(struct panthor_heap_pool *pool); > > void panthor_heap_pool_put(struct panthor_heap_pool *pool); > > > > -size_t panthor_heap_pool_size(struct panthor_heap_pool *pool); > > - > > int panthor_heap_grow(struct panthor_heap_pool *pool, > > u64 heap_gpu_va, > > u32 renderpasses_in_flight, > > diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c > > index 0a4e352b5505..aaad1a560805 100644 > > --- a/drivers/gpu/drm/panthor/panthor_mmu.c > > +++ b/drivers/gpu/drm/panthor/panthor_mmu.c > > @@ -345,6 +345,10 @@ struct panthor_vm { > > > > /** @heaps.lock: Lock used to protect access to @pool. */ > > struct mutex lock; > > + > > + /** @heaps.size: Size of all chunks across all heaps in the pool. */ > > + ssize_t size; > > Let's put that into an fdinfo struct. > > > + > > Drop the extra blank-line. > > > } heaps; > > > > /** @node: Used to insert the VM in the panthor_mmu::vm::list. */ > > @@ -1539,6 +1543,7 @@ static void panthor_vm_destroy(struct panthor_vm *vm) > > mutex_lock(&vm->heaps.lock); > > panthor_heap_pool_destroy(vm->heaps.pool); > > vm->heaps.pool = NULL; > > + vm->heaps.size = 0; > > mutex_unlock(&vm->heaps.lock); > > > > drm_WARN_ON(&vm->ptdev->base, > > @@ -1963,13 +1968,7 @@ void panthor_vm_heaps_sizes(struct panthor_file *pfile, struct drm_memory_stats > > > > xa_lock(&pfile->vms->xa); > > xa_for_each(&pfile->vms->xa, i, vm) { > > - size_t size = 0; > > - > > - mutex_lock(&vm->heaps.lock); > > - if (vm->heaps.pool) > > - size = panthor_heap_pool_size(vm->heaps.pool); > > - mutex_unlock(&vm->heaps.lock); > > - > > + size_t size = vm->heaps.size; > > stats->resident += size; > > if (vm->as.id >= 0) > > stats->active += size; > > @@ -1977,6 +1976,11 @@ void panthor_vm_heaps_sizes(struct panthor_file *pfile, struct drm_memory_stats > > xa_unlock(&pfile->vms->xa); > > } > > > > +void panthor_vm_heaps_accumulate(struct panthor_vm *vm, ssize_t acc) > > +{ > > Either there's some lock protecting this operation and we want a > lockdep_assert_held(), or we need to make it an atomic operation (and > make the size an atomic_t) to avoid races. If Adrián moves the call site in panthor_{alloc,free}_heap_chunk() before he drops the heap->lock, would that be sufficient? Pool create and destroy are hopefully race-free and panthor_heap_return_chunk() should be also safe. Best regards, Liviu > > > + vm->heaps.size += acc; > > +} > > + > > static u64 mair_to_memattr(u64 mair, bool coherent) > > { > > u64 memattr = 0; > > diff --git a/drivers/gpu/drm/panthor/panthor_mmu.h b/drivers/gpu/drm/panthor/panthor_mmu.h > > index fc274637114e..b6686896f8ef 100644 > > --- a/drivers/gpu/drm/panthor/panthor_mmu.h > > +++ b/drivers/gpu/drm/panthor/panthor_mmu.h > > @@ -39,6 +39,7 @@ struct panthor_heap_pool * > > panthor_vm_get_heap_pool(struct panthor_vm *vm, bool create); > > > > void panthor_vm_heaps_sizes(struct panthor_file *pfile, struct drm_memory_stats *stats); > > +void panthor_vm_heaps_accumulate(struct panthor_vm *vm, ssize_t acc); > > > > struct panthor_vm *panthor_vm_get(struct panthor_vm *vm); > > void panthor_vm_put(struct panthor_vm *vm); > -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯