From: Damien Le Moal Date: Fri, 27 Feb 2026 13:19:50 +0000 (+0900) Subject: block: default to QD=1 writes for blk-mq rotational zoned devices X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3d9782f62fb7c2c9ec3020c579425d634559d600;p=thirdparty%2Fkernel%2Flinux.git block: default to QD=1 writes for blk-mq rotational zoned devices For blk-mq rotational zoned block devices (e.g. SMR HDDs), default to having zone write plugging limit write operations to a maximum queue depth of 1 for all zones. This significantly reduce write seek overhead and improves SMR HDD write throughput. For remotely connected disks with a very high network latency this features might not be useful. However, remotely connected zoned devices are rare at the moment, and we cannot know the round trip latency to pick a good default for network attached devices. System administrators can however disable this feature in that case. For BIO based (non blk-mq) rotational zoned block devices, the device driver (e.g. a DM target driver) can directly set an appropriate default. Signed-off-by: Damien Le Moal Reviewed-by: Hannes Reinecke Reviewed-by: Christoph Hellwig Reviewed-by: Bart Van Assche Reviewed-by: Johannes Thumshirn Signed-off-by: Jens Axboe --- diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index ca8033e6d6990..878b8a4b55bb6 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -967,6 +967,14 @@ int blk_register_queue(struct gendisk *disk) blk_mq_debugfs_register(q); blk_debugfs_unlock(q, memflags); + /* + * For blk-mq rotational zoned devices, default to using QD=1 + * writes. For non-mq rotational zoned devices, the device driver can + * set an appropriate default. + */ + if (queue_is_mq(q) && blk_queue_rot(q) && blk_queue_is_zoned(q)) + blk_queue_flag_set(QUEUE_FLAG_ZONED_QD1_WRITES, q); + ret = disk_register_independent_access_ranges(disk); if (ret) goto out_debugfs_remove;