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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E6844C433F5 for ; Wed, 9 Mar 2022 11:55:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232520AbiCIL4n (ORCPT ); Wed, 9 Mar 2022 06:56:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57198 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232530AbiCIL4k (ORCPT ); Wed, 9 Mar 2022 06:56:40 -0500 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [46.235.227.227]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E379A996D for ; Wed, 9 Mar 2022 03:55:41 -0800 (PST) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: dmitry.osipenko) with ESMTPSA id 5D8B61F44A74 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1646826940; bh=dJmw4zOrIHkURAmLQiTZMGndrEkge+z8fLKmyH944ng=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=lzcJwR+xt1Hi8zjGE4UgpY3rbII3w72kn/wdkoJY0oZKJ9pzvD/YNCuQY2JgOUcgu IIMJ4teyyYm+lIooNRL4ucJE4cCnUAK2tGNpc2vZqkp7yjbHxivzwLqJHF+wWk7bd7 AbfK1dYuMW9v4Pj1MHR8nDciE0aJij8ookDYocuwVasuo8i42d6G+I6ORcCYE/rXBc HHpJ3VRi5ynK0kzALfafF87gYjdAAD1w4DzDqYd5MdOdL0Lv0Qg/lZXqz5TIh4xNRd F7qa8nuXGqfb6EFSdLlQt7VUaiqXMzPL7vK78nwEiPw/xoPmUxGl/7kaktl/W6ke/F P53OZjZwjW4zA== Message-ID: <26ab770d-4b59-a25a-79ef-e43858e7b67b@collabora.com> Date: Wed, 9 Mar 2022 14:55:36 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH v1 5/5] drm/virtio: Add memory shrinker Content-Language: en-US To: Rob Clark Cc: David Airlie , Gerd Hoffmann , Gurchetan Singh , Chia-I Wu , Daniel Vetter , Daniel Almeida , Gert Wollny , Tomeu Vizoso , Linux Kernel Mailing List , "open list:VIRTIO GPU DRIVER" , Gustavo Padovan , dri-devel , Dmitry Osipenko References: <20220308131725.60607-1-dmitry.osipenko@collabora.com> <20220308131725.60607-6-dmitry.osipenko@collabora.com> From: Dmitry Osipenko In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/9/22 04:12, Rob Clark wrote: >> +static unsigned long >> +virtio_gpu_gem_shrinker_count_objects(struct shrinker *shrinker, >> + struct shrink_control *sc) >> +{ >> + struct drm_gem_shmem_object *shmem; >> + struct virtio_gpu_device *vgdev; >> + unsigned long count = 0; >> + bool empty = true; >> + >> + vgdev = container_of(shrinker, struct virtio_gpu_device, >> + vgshrinker.shrinker); >> + >> + if (!mutex_trylock(&vgdev->mm_lock)) >> + return 0; > One bit of advice from previously dealing with shrinker and heavy > memory pressure situations (turns out 4GB chromebooks can be pretty > much under *constant* memory pressure): > > You *really* want to make shrinker->count_objects lockless.. and > minimize the lock contention on shrinker->scan_objects (ie. The > problem is you can end up with shrinking going on on all CPU cores in > parallel, you want to not funnel that thru one lock as much as > possible. > > See in particular: > > 25ed38b3ed26 ("drm/msm: Drop mm_lock in scan loop") > cc8a4d5a1bd8 ("drm/msm: Avoid mutex in shrinker_count()") Thank you, I'll take that into account for v2. 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 1B216C433F5 for ; Wed, 9 Mar 2022 11:55:44 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 15A6210E3E7; Wed, 9 Mar 2022 11:55:43 +0000 (UTC) Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [46.235.227.227]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9470510E3E7 for ; Wed, 9 Mar 2022 11:55:41 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: dmitry.osipenko) with ESMTPSA id 5D8B61F44A74 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1646826940; bh=dJmw4zOrIHkURAmLQiTZMGndrEkge+z8fLKmyH944ng=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=lzcJwR+xt1Hi8zjGE4UgpY3rbII3w72kn/wdkoJY0oZKJ9pzvD/YNCuQY2JgOUcgu IIMJ4teyyYm+lIooNRL4ucJE4cCnUAK2tGNpc2vZqkp7yjbHxivzwLqJHF+wWk7bd7 AbfK1dYuMW9v4Pj1MHR8nDciE0aJij8ookDYocuwVasuo8i42d6G+I6ORcCYE/rXBc HHpJ3VRi5ynK0kzALfafF87gYjdAAD1w4DzDqYd5MdOdL0Lv0Qg/lZXqz5TIh4xNRd F7qa8nuXGqfb6EFSdLlQt7VUaiqXMzPL7vK78nwEiPw/xoPmUxGl/7kaktl/W6ke/F P53OZjZwjW4zA== Message-ID: <26ab770d-4b59-a25a-79ef-e43858e7b67b@collabora.com> Date: Wed, 9 Mar 2022 14:55:36 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH v1 5/5] drm/virtio: Add memory shrinker Content-Language: en-US To: Rob Clark References: <20220308131725.60607-1-dmitry.osipenko@collabora.com> <20220308131725.60607-6-dmitry.osipenko@collabora.com> From: Dmitry Osipenko In-Reply-To: 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: , Cc: Gert Wollny , Tomeu Vizoso , Gustavo Padovan , David Airlie , Linux Kernel Mailing List , dri-devel , Gurchetan Singh , Daniel Almeida , Gerd Hoffmann , Dmitry Osipenko , "open list:VIRTIO GPU DRIVER" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 3/9/22 04:12, Rob Clark wrote: >> +static unsigned long >> +virtio_gpu_gem_shrinker_count_objects(struct shrinker *shrinker, >> + struct shrink_control *sc) >> +{ >> + struct drm_gem_shmem_object *shmem; >> + struct virtio_gpu_device *vgdev; >> + unsigned long count = 0; >> + bool empty = true; >> + >> + vgdev = container_of(shrinker, struct virtio_gpu_device, >> + vgshrinker.shrinker); >> + >> + if (!mutex_trylock(&vgdev->mm_lock)) >> + return 0; > One bit of advice from previously dealing with shrinker and heavy > memory pressure situations (turns out 4GB chromebooks can be pretty > much under *constant* memory pressure): > > You *really* want to make shrinker->count_objects lockless.. and > minimize the lock contention on shrinker->scan_objects (ie. The > problem is you can end up with shrinking going on on all CPU cores in > parallel, you want to not funnel that thru one lock as much as > possible. > > See in particular: > > 25ed38b3ed26 ("drm/msm: Drop mm_lock in scan loop") > cc8a4d5a1bd8 ("drm/msm: Avoid mutex in shrinker_count()") Thank you, I'll take that into account for v2.