On 5/27/21 3:01 AM, Bart Van Assche wrote: > For interactive workloads it is important that synchronous requests are > not delayed. Hence reserve 25% of tags for synchronous requests. This patch > still allows asynchronous requests to fill the hardware queues since > blk_mq_init_sched() makes sure that the number of scheduler requests is the > double of the hardware queue depth. From blk_mq_init_sched(): > > q->nr_requests = 2 * min_t(unsigned int, q->tag_set->queue_depth, > BLKDEV_MAX_RQ); > > Cc: Damien Le Moal <damien.lemoal@xxxxxxx> > Cc: Christoph Hellwig <hch@xxxxxx> > Cc: Ming Lei <ming.lei@xxxxxxxxxx> > Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx> > --- > block/mq-deadline.c | 46 +++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 46 insertions(+) > I wonder if that's a good idea in general ... I'm thinking of poor SATA drives which only have 31 tags; setting aside 8 of them for specific use-cases does make a difference one would think. Do you have testcases for this? Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@xxxxxxx +49 911 74053 688 SUSE Software Solutions Germany GmbH, 90409 Nürnberg GF: F. Imendörffer, HRB 36809 (AG Nürnberg)
