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Commit fc1bc354 authored by Matias Bjørling's avatar Matias Bjørling Committed by Jens Axboe
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null_blk: support submit_queues on use_per_node_hctx 



In the case of both the submit_queues param and use_per_node_hctx param
are used. We limit the number af submit_queues to the number of online
nodes.

If the submit_queues is a multiple of nr_online_nodes, its trivial. Simply map
them to the nodes. For example: 8 submit queues are mapped as node0[0,1],
node1[2,3], ...
If uneven, we are left with an uneven number of submit_queues that must be
mapped. These are mapped toward the first node and onward. E.g. 5
submit queues mapped onto 4 nodes are mapped as node0[0,1], node1[2], ...

Signed-off-by: default avatarMatias Bjorling <m@bjorling.me>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 20005244

drivers/block/null_blk.c

+35 −4
Original line number Diff line number Diff line 
#include <linux/module.h>



#include <linux/moduleparam.h>

#include <linux/sched.h>

#include <linux/fs.h>
@@ -346,8 +347,37 @@ static int null_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *rq) 


static struct blk_mq_hw_ctx *null_alloc_hctx(struct blk_mq_reg *reg, unsigned int hctx_index)

{

	return kzalloc_node(sizeof(struct blk_mq_hw_ctx), GFP_KERNEL,

				hctx_index);

	int b_size = DIV_ROUND_UP(reg->nr_hw_queues, nr_online_nodes);

	int tip = (reg->nr_hw_queues % nr_online_nodes);

	int node = 0, i, n;



	/*

	 * Split submit queues evenly wrt to the number of nodes. If uneven,

	 * fill the first buckets with one extra, until the rest is filled with

	 * no extra.

	 */

	for (i = 0, n = 1; i < hctx_index; i++, n++) {

		if (n % b_size == 0) {

			n = 0;

			node++;



			tip--;

			if (!tip)

				b_size = reg->nr_hw_queues / nr_online_nodes;

		}

	}



	/*

	 * A node might not be online, therefore map the relative node id to the

	 * real node id.

	 */

	for_each_online_node(n) {

		if (!node)

			break;

		node--;

	}



	return kzalloc_node(sizeof(struct blk_mq_hw_ctx), GFP_KERNEL, n);

}



static void null_free_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_index)
@@ -591,10 +621,11 @@ static int __init null_init(void) 
#endif



	if (queue_mode == NULL_Q_MQ && use_per_node_hctx) {

		if (submit_queues > 0)

		if (submit_queues < nr_online_nodes) {

			pr_warn("null_blk: submit_queues param is set to %u.",

							nr_online_nodes);

			submit_queues = nr_online_nodes;

		}

	} else if (submit_queues > nr_cpu_ids)

		submit_queues = nr_cpu_ids;

	else if (!submit_queues)