* null_blk: add blocking mode
@ 2017-03-30 18:53 Jens Axboe
2017-03-30 19:33 ` Bart Van Assche
0 siblings, 1 reply; 2+ messages in thread
From: Jens Axboe @ 2017-03-30 18:53 UTC (permalink / raw)
To: linux-block; +Cc: Christoph Hellwig
This adds a new module parameter to null_blk, blocking. If set, null_blk
will set the BLK_MQ_F_BLOCKING flag, indicating that it sometimes/always
needs to block in its ->queue_rq() function. The intent is to help find
regressions in blocking drivers, since not many of them exist.
If null_blk is loaded with submit_queues > 1 and blocking=1, this
shows the regression recently fixed by bf4907c05e61.
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 6f2e565..d95635f 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -117,6 +117,10 @@ static bool use_lightnvm;
module_param(use_lightnvm, bool, S_IRUGO);
MODULE_PARM_DESC(use_lightnvm, "Register as a LightNVM device");
+static bool blocking;
+module_param(blocking, bool, S_IRUGO);
+MODULE_PARM_DESC(blocking, "Register as a blocking blk-mq driver device");
+
static int irqmode = NULL_IRQ_SOFTIRQ;
static int null_set_irqmode(const char *str, const struct kernel_param *kp)
@@ -357,6 +361,8 @@ static int null_queue_rq(struct blk_mq_hw_ctx *hctx,
{
struct nullb_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
+ might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
+
if (irqmode == NULL_IRQ_TIMER) {
hrtimer_init(&cmd->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
cmd->timer.function = null_cmd_timer_expired;
@@ -724,6 +730,9 @@ static int null_add_dev(void)
nullb->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
nullb->tag_set.driver_data = nullb;
+ if (blocking)
+ nullb->tag_set.flags |= BLK_MQ_F_BLOCKING;
+
rv = blk_mq_alloc_tag_set(&nullb->tag_set);
if (rv)
goto out_cleanup_queues;
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: null_blk: add blocking mode
2017-03-30 18:53 null_blk: add blocking mode Jens Axboe
@ 2017-03-30 19:33 ` Bart Van Assche
0 siblings, 0 replies; 2+ messages in thread
From: Bart Van Assche @ 2017-03-30 19:33 UTC (permalink / raw)
To: Jens Axboe, linux-block; +Cc: Christoph Hellwig
On 03/30/2017 11:53 AM, Jens Axboe wrote:=0A=
> This adds a new module parameter to null_blk, blocking. If set, null_blk=
=0A=
> will set the BLK_MQ_F_BLOCKING flag, indicating that it sometimes/always=
=0A=
> needs to block in its ->queue_rq() function. The intent is to help find=
=0A=
> regressions in blocking drivers, since not many of them exist.=0A=
> =0A=
> If null_blk is loaded with submit_queues > 1 and blocking=3D1, this=0A=
> shows the regression recently fixed by bf4907c05e61.=0A=
=0A=
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>=0A=
^ permalink raw reply [flat|nested] 2+ messages in thread
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