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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: Matias Bjorling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Matias Bjørling 2013-12-21 00:11:01 +01:00 committed by Jens Axboe
parent 200052440d
commit fc1bc35443
1 changed files with 35 additions and 4 deletions
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39
drivers/block/null_blk.c
View File

@ -1,4 +1,5 @@
#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;
submit_queues = nr_online_nodes;
}
} else if (submit_queues > nr_cpu_ids)
submit_queues = nr_cpu_ids;
else if (!submit_queues)