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Commit 6e219353 authored by Stephen Bates's avatar Stephen Bates Committed by Jens Axboe
Browse files

block: add poll_considered statistic 



In order to help determine the effectiveness of polling in a running
system it is usful to determine the ratio of how often the poll
function is called vs how often the completion is checked. For this
reason we add a poll_considered variable and add it to the sysfs entry
for io_poll.

Signed-off-by: default avatarStephen Bates <sbates@raithlin.com>
Acked-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 0eadf37a

block/blk-core.c

+6 −2
Original line number Diff line number Diff line
@@ -3307,19 +3307,23 @@ bool blk_poll(struct request_queue *q, blk_qc_t cookie) 
{

	struct blk_plug *plug;

	long state;

	unsigned int queue_num;

	struct blk_mq_hw_ctx *hctx;



	if (!q->mq_ops || !q->mq_ops->poll || !blk_qc_t_valid(cookie) ||

	    !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))

		return false;



	queue_num = blk_qc_t_to_queue_num(cookie);

	hctx = q->queue_hw_ctx[queue_num];

	hctx->poll_considered++;



	plug = current->plug;

	if (plug)

		blk_flush_plug_list(plug, false);



	state = current->state;

	while (!need_resched()) {

		unsigned int queue_num = blk_qc_t_to_queue_num(cookie);

		struct blk_mq_hw_ctx *hctx = q->queue_hw_ctx[queue_num];

		int ret;



		hctx->poll_invoked++;

block/blk-mq-sysfs.c

+3 −1
Original line number Diff line number Diff line
@@ -176,7 +176,9 @@ static ssize_t blk_mq_sysfs_rq_list_show(struct blk_mq_ctx *ctx, char *page) 


static ssize_t blk_mq_hw_sysfs_poll_show(struct blk_mq_hw_ctx *hctx, char *page)

{

	return sprintf(page, "invoked=%lu, success=%lu\n", hctx->poll_invoked, hctx->poll_success);

	return sprintf(page, "considered=%lu, invoked=%lu, success=%lu\n",

		       hctx->poll_considered, hctx->poll_invoked,

		       hctx->poll_success);

}



static ssize_t blk_mq_hw_sysfs_queued_show(struct blk_mq_hw_ctx *hctx,

include/linux/blk-mq.h

+1 −0
Original line number Diff line number Diff line
@@ -61,6 +61,7 @@ struct blk_mq_hw_ctx { 
	struct blk_mq_cpu_notifier	cpu_notifier;

	struct kobject		kobj;



	unsigned long		poll_considered;

	unsigned long		poll_invoked;

	unsigned long		poll_success;

};