From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D3C86CF8865 for ; Thu, 20 Nov 2025 15:25:05 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 27AC310E771; Thu, 20 Nov 2025 15:25:05 +0000 (UTC) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by gabe.freedesktop.org (Postfix) with ESMTP id 8798C10E771 for ; Thu, 20 Nov 2025 15:25:03 +0000 (UTC) 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 8C59A339; Thu, 20 Nov 2025 07:24:55 -0800 (PST) Received: from [10.1.32.17] (unknown [10.1.32.17]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D9A763F66E; Thu, 20 Nov 2025 07:25:00 -0800 (PST) Message-ID: <949604fd-08fd-47f5-a0b0-60087c033d41@arm.com> Date: Thu, 20 Nov 2025 15:24:58 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drm/panthor: Avoid adding of kernel BOs to extobj list To: Akash Goel , boris.brezillon@collabora.com, liviu.dudau@arm.com Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, daniel@ffwll.ch, nd@arm.com References: <20251113184544.1832461-1-akash.goel@arm.com> From: Steven Price Content-Language: en-GB In-Reply-To: <20251113184544.1832461-1-akash.goel@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 13/11/2025 18:45, Akash Goel wrote: > The kernel BOs unnecessarily got added to the external objects list > of drm_gpuvm, when mapping to GPU, which would have resulted in few > extra CPU cycles being spent at the time of job submission as > drm_exec_until_all_locked() loop iterates over all external objects. > > Kernel BOs are private to a VM and so they share the dma_resv object of > the dummy GEM object created for a VM. Use of DRM_EXEC_IGNORE_DUPLICATES > flag ensured the recursive locking of the dummy GEM object was ignored. > Also no extra space got allocated to add fences to the dma_resv object > of dummy GEM object. So no other impact apart from few extra CPU cycles. > > This commit sets the pointer to dma_resv object of GEM object of > kernel BOs before they are mapped to GPU, to prevent them from > being added to external objects list. > > Signed-off-by: Akash Goel Reviewed-by: Steven Price As Boris says it would be good to have a Fixes tag - can you dig out an appropriate commit then I can merge? Thanks, Steve > --- > drivers/gpu/drm/panthor/panthor_gem.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c > index f369cc3e2a5f..10d255cccc09 100644 > --- a/drivers/gpu/drm/panthor/panthor_gem.c > +++ b/drivers/gpu/drm/panthor/panthor_gem.c > @@ -145,6 +145,9 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm, > bo = to_panthor_bo(&obj->base); > kbo->obj = &obj->base; > bo->flags = bo_flags; > + bo->exclusive_vm_root_gem = panthor_vm_root_gem(vm); > + drm_gem_object_get(bo->exclusive_vm_root_gem); > + bo->base.base.resv = bo->exclusive_vm_root_gem->resv; > > if (vm == panthor_fw_vm(ptdev)) > debug_flags |= PANTHOR_DEBUGFS_GEM_USAGE_FLAG_FW_MAPPED; > @@ -168,9 +171,6 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm, > goto err_free_va; > > kbo->vm = panthor_vm_get(vm); > - bo->exclusive_vm_root_gem = panthor_vm_root_gem(vm); > - drm_gem_object_get(bo->exclusive_vm_root_gem); > - bo->base.base.resv = bo->exclusive_vm_root_gem->resv; > return kbo; > > err_free_va: