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Subject[PATCH V2 3/4] blk-mq: realloc hctx when hw queue is mapped to another node
Date
When the hw queues and mq_map are updated, a hctx could be mapped
to a different numa node. At this moment, we need to realloc the
hctx. If fail to do that, go on using previous hctx.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
---
block/blk-mq.c | 82 +++++++++++++++++++++++++++++++++++++++-------------------
1 file changed, 56 insertions(+), 26 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 9805d6a..34f3973 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2504,6 +2504,39 @@ static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
return hw_ctx_size;
}

+static struct blk_mq_hw_ctx *blk_mq_alloc_and_init_hctx(
+ struct blk_mq_tag_set *set, struct request_queue *q,
+ int hctx_idx, int node)
+{
+ struct blk_mq_hw_ctx *hctx;
+
+ hctx = kzalloc_node(blk_mq_hw_ctx_size(set),
+ GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
+ node);
+ if (!hctx)
+ return NULL;
+
+ if (!zalloc_cpumask_var_node(&hctx->cpumask,
+ GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
+ node)) {
+ kfree(hctx);
+ return NULL;
+ }
+
+ atomic_set(&hctx->nr_active, 0);
+ hctx->numa_node = node;
+ hctx->queue_num = hctx_idx;
+
+ if (blk_mq_init_hctx(q, set, hctx, hctx_idx)) {
+ free_cpumask_var(hctx->cpumask);
+ kfree(hctx);
+ return NULL;
+ }
+ blk_mq_hctx_kobj_init(hctx);
+
+ return hctx;
+}
+
static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
struct request_queue *q)
{
@@ -2514,37 +2547,34 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
mutex_lock(&q->sysfs_lock);
for (i = 0; i < set->nr_hw_queues; i++) {
int node;
-
- if (hctxs[i])
- continue;
+ struct blk_mq_hw_ctx *hctx;

node = blk_mq_hw_queue_to_node(q->mq_map, i);
- hctxs[i] = kzalloc_node(blk_mq_hw_ctx_size(set),
- GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
- node);
- if (!hctxs[i])
- break;
-
- if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask,
- GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
- node)) {
- kfree(hctxs[i]);
- hctxs[i] = NULL;
- break;
- }
-
- atomic_set(&hctxs[i]->nr_active, 0);
- hctxs[i]->numa_node = node;
- hctxs[i]->queue_num = i;
+ /*
+ * If the hw queue has been mapped to another numa node,
+ * we need to realloc the hctx. If allocation fails, fallback
+ * to use the previous one.
+ */
+ if (hctxs[i] && (hctxs[i]->numa_node == node))
+ continue;

- if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
- free_cpumask_var(hctxs[i]->cpumask);
- kfree(hctxs[i]);
- hctxs[i] = NULL;
- break;
+ hctx = blk_mq_alloc_and_init_hctx(set, q, i, node);
+ if (hctx) {
+ if (hctxs[i]) {
+ blk_mq_exit_hctx(q, set, hctxs[i], i);
+ kobject_put(&hctxs[i]->kobj);
+ }
+ hctxs[i] = hctx;
+ } else {
+ if (hctxs[i])
+ pr_warn("Allocate new hctx on node %d fails,\
+ fallback to previous one on node %d\n",
+ node, hctxs[i]->numa_node);
+ else
+ break;
}
- blk_mq_hctx_kobj_init(hctxs[i]);
}
+
for (j = i; j < q->nr_hw_queues; j++) {
struct blk_mq_hw_ctx *hctx = hctxs[j];

--
2.7.4
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