GitHub-Mirror/linux-bl808
2
0
Fork 0
mirror of https://github.com/Fishwaldo/linux-bl808.git synced 2025-06-17 20:25:19 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

scsi: blk-mq: Return budget token from .get_budget callback

Browse source 
SCSI uses a global atomic variable to track queue depth for each
LUN/request queue.

This doesn't scale well when there are lots of CPU cores and the disk is
very fast. It has been observed that IOPS is affected a lot by tracking
queue depth via sdev->device_busy in the I/O path.

Return budget token from .get_budget callback. The budget token can be
passed to driver so that we can replace the atomic variable with
sbitmap_queue and alleviate the scaling problems that way.

Link: https://lore.kernel.org/r/20210122023317.687987-9-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Ming Lei 2021-01-22 10:33:12 +08:00 • committed by Martin K. Petersen
parent d022d18c04
commit 2a5a24aa83
5 changed files with 72 additions and 26 deletions
Download patch file Download diff file Expand all files Collapse all files

4
include/linux/blk-mq.h
View file

@ -306,12 +306,12 @@ struct blk_mq_ops {
* reserved budget. Also we have to handle failure case
* of .get_budget for avoiding I/O deadlock.
*/
bool (*get_budget)(struct request_queue *);
int (*get_budget)(struct request_queue *);
/**
* @put_budget: Release the reserved budget.
*/
void (*put_budget)(struct request_queue *);
void (*put_budget)(struct request_queue *, int);
/*
* @set_rq_budget_toekn: store rq's budget token