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Tsirkin" CC: Stefan Hajnoczi , , , , , , , , References: <20210831135035.6443-1-mgurtovoy@nvidia.com> <20210905120234-mutt-send-email-mst@kernel.org> <98309fcd-3abe-1f27-fe52-e8fcc58bec13@nvidia.com> <20210906071957-mutt-send-email-mst@kernel.org> <1cbbe6e2-1473-8696-565c-518fc1016a1a@nvidia.com> <20210909094001-mutt-send-email-mst@kernel.org> From: Max Gurtovoy Message-ID: <456e1704-67e9-aac9-a82a-44fed65dd153@nvidia.com> Date: Thu, 9 Sep 2021 18:37:37 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20210909094001-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [172.20.187.6] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To DRHQMAIL107.nvidia.com (10.27.9.16) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 1fa7350e-dc0d-4a1f-01b0-08d973a7c441 X-MS-TrafficTypeDiagnostic: MN2PR12MB4343: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:8273; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.112.35;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:schybrid02.nvidia.com;CAT:NONE;SFS:(4636009)(396003)(346002)(376002)(39860400002)(136003)(46966006)(36840700001)(478600001)(5660300002)(36906005)(36860700001)(31696002)(16576012)(31686004)(2616005)(53546011)(82310400003)(316002)(86362001)(47076005)(83380400001)(8676002)(70586007)(70206006)(36756003)(26005)(336012)(16526019)(6666004)(186003)(426003)(356005)(82740400003)(6916009)(2906002)(54906003)(4326008)(7636003)(8936002)(43740500002);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Sep 2021 15:37:43.7883 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 1fa7350e-dc0d-4a1f-01b0-08d973a7c441 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.112.35];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: DM6NAM11FT062.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4343 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 9/9/2021 4:42 PM, Michael S. Tsirkin wrote: > On Mon, Sep 06, 2021 at 02:59:40PM +0300, Max Gurtovoy wrote: >> On 9/6/2021 2:20 PM, Michael S. Tsirkin wrote: >>> On Mon, Sep 06, 2021 at 01:31:32AM +0300, Max Gurtovoy wrote: >>>> On 9/5/2021 7:02 PM, Michael S. Tsirkin wrote: >>>>> On Thu, Sep 02, 2021 at 02:45:52PM +0100, Stefan Hajnoczi wrote: >>>>>> On Tue, Aug 31, 2021 at 04:50:35PM +0300, Max Gurtovoy wrote: >>>>>>> Sometimes a user would like to control the amount of IO queues to be >>>>>>> created for a block device. For example, for limiting the memory >>>>>>> footprint of virtio-blk devices. >>>>>>> >>>>>>> Signed-off-by: Max Gurtovoy >>>>>>> --- >>>>>>> >>>>>>> changes from v1: >>>>>>> - use param_set_uint_minmax (from Christoph) >>>>>>> - added "Should > 0" to module description >>>>>>> >>>>>>> Note: This commit apply on top of Jens's branch for-5.15/drivers >>>>>>> --- >>>>>>> drivers/block/virtio_blk.c | 20 +++++++++++++++++++- >>>>>>> 1 file changed, 19 insertions(+), 1 deletion(-) >>>>>>> >>>>>>> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c >>>>>>> index 4b49df2dfd23..9332fc4e9b31 100644 >>>>>>> --- a/drivers/block/virtio_blk.c >>>>>>> +++ b/drivers/block/virtio_blk.c >>>>>>> @@ -24,6 +24,22 @@ >>>>>>> /* The maximum number of sg elements that fit into a virtqueue */ >>>>>>> #define VIRTIO_BLK_MAX_SG_ELEMS 32768 >>>>>>> +static int virtblk_queue_count_set(const char *val, >>>>>>> + const struct kernel_param *kp) >>>>>>> +{ >>>>>>> + return param_set_uint_minmax(val, kp, 1, nr_cpu_ids); >>>>>>> +} >>> Hmm which tree is this for? >> I've mentioned in the note that it apply on branch for-5.15/drivers. But now >> you can apply it on linus/master as well. >> >> >>>>>>> + >>>>>>> +static const struct kernel_param_ops queue_count_ops = { >>>>>>> + .set = virtblk_queue_count_set, >>>>>>> + .get = param_get_uint, >>>>>>> +}; >>>>>>> + >>>>>>> +static unsigned int num_io_queues; >>>>>>> +module_param_cb(num_io_queues, &queue_count_ops, &num_io_queues, 0644); >>>>>>> +MODULE_PARM_DESC(num_io_queues, >>>>>>> + "Number of IO virt queues to use for blk device. Should > 0"); >>> >>> better: >>> >>> +MODULE_PARM_DESC(num_io_request_queues, >>> + "Limit number of IO request virt queues to use for each device. 0 for now limit"); >> You proposed it and I replied on it bellow. > > Can't say I understand 100% what you are saying. Want to send > a description that does make sense to you but > also reflects reality? 0 is the default so > "should > 0" besides being ungrammatical does not seem t" > reflect what it does ... if you "modprobe virtio_blk" the previous behavior will happen. You can't "modprobe virtio_blk num_io_request_queues=0" since the minimal value is 1. So your description is not reflecting the code. We can do: MODULE_PARM_DESC(num_io_request_queues, "Number of request virt queues to use for blk device. Minimum value is 1 queue"); > >>> >>>>>>> + >>>>>>> static int major; >>>>>>> static DEFINE_IDA(vd_index_ida); >>>>>>> @@ -501,7 +517,9 @@ static int init_vq(struct virtio_blk *vblk) >>>>>>> if (err) >>>>>>> num_vqs = 1; >>>>>>> - num_vqs = min_t(unsigned int, nr_cpu_ids, num_vqs); >>>>>>> + num_vqs = min_t(unsigned int, >>>>>>> + min_not_zero(num_io_queues, nr_cpu_ids), >>>>>>> + num_vqs); >>>>>> If you respin, please consider calling them request queues. That's the >>>>>> terminology from the VIRTIO spec and it's nice to keep it consistent. >>>>>> But the purpose of num_io_queues is clear, so: >>>>>> >>>>>> Reviewed-by: Stefan Hajnoczi >>>>> I did this: >>>>> +static unsigned int num_io_request_queues; >>>>> +module_param_cb(num_io_request_queues, &queue_count_ops, &num_io_request_queues, 0644); >>>>> +MODULE_PARM_DESC(num_io_request_queues, >>>>> + "Limit number of IO request virt queues to use for each device. 0 for now limit"); >>>> The parameter is writable and can be changed and then new devices might be >>>> probed with new value. >>>> >>>> It can't be zero in the code. we can change param_set_uint_minmax args and >>>> say that 0 says nr_cpus. >>>> >>>> I'm ok with the renaming but I prefer to stick to the description we gave in >>>> V3 of this patch (and maybe enable value of 0 as mentioned above).