The current code computes a number of channels per SRP target and spreads
them equally across all online NUMA nodes.
Each channel is then assigned a CPU within this node.
In the case of unbalanced, or even unpopulated nodes, some channels
do not get a CPU associated and thus do not get connected.
This causes the SRP connection to fail.
This patch solves the issue by rewriting channel computation and allocation:
- Drop channel to node/CPU association as it had
no real effect on locality but added unnecessary complexity.
- Tweak the number of channels allocated to reduce CPU contention when possible:
- Up to one channel per CPU (instead of up to 4 by node)
- At least 4 channels per node, unless ch_count module parameter is used.
Signed-off-by: Nicolas Morey-Chaisemartin <nmoreychaisemartin@xxxxxxxx>
---
drivers/infiniband/ulp/srp/ib_srp.c | 110 ++++++++++++----------------
1 file changed, 45 insertions(+), 65 deletions(-)
diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 5492b66a8153..31f8aa2c40ed 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -3628,7 +3628,7 @@ static ssize_t srp_create_target(struct device *dev,
struct srp_rdma_ch *ch;
struct srp_device *srp_dev = host->srp_dev;
struct ib_device *ibdev = srp_dev->dev;
- int ret, node_idx, node, cpu, i;
+ int ret, i, ch_idx;
unsigned int max_sectors_per_mr, mr_per_cmd = 0;
bool multich = false;
uint32_t max_iu_len;
@@ -3753,81 +3753,61 @@ static ssize_t srp_create_target(struct device *dev,
goto out;
ret = -ENOMEM;
- if (target->ch_count == 0)
+ if (target->ch_count == 0) {
target->ch_count =
- max_t(unsigned int, num_online_nodes(),
- min(ch_count ?:
- min(4 * num_online_nodes(),
- ibdev->num_comp_vectors),
- num_online_cpus()));
+ min(ch_count ?:
+ max(4 * num_online_nodes(),
+ ibdev->num_comp_vectors),
+ num_online_cpus());
+ }
+
target->ch = kcalloc(target->ch_count, sizeof(*target->ch),
GFP_KERNEL);
if (!target->ch)
goto out;
- node_idx = 0;
- for_each_online_node(node) {
- const int ch_start = (node_idx * target->ch_count /
- num_online_nodes());
- const int ch_end = ((node_idx + 1) * target->ch_count /
- num_online_nodes());
- const int cv_start = node_idx * ibdev->num_comp_vectors /
- num_online_nodes();
- const int cv_end = (node_idx + 1) * ibdev->num_comp_vectors /
- num_online_nodes();
- int cpu_idx = 0;
-
- for_each_online_cpu(cpu) {
- if (cpu_to_node(cpu) != node)
- continue;
- if (ch_start + cpu_idx >= ch_end)
- continue;
- ch = &target->ch[ch_start + cpu_idx];
- ch->target = target;
- ch->comp_vector = cv_start == cv_end ? cv_start :
- cv_start + cpu_idx % (cv_end - cv_start);
- spin_lock_init(&ch->lock);
- INIT_LIST_HEAD(&ch->free_tx);
- ret = srp_new_cm_id(ch);
- if (ret)
- goto err_disconnect;
+ for (ch_idx = 0; ch_idx < target->ch_count; ++ch_idx) {
+ ch = &target->ch[ch_idx];
+ ch->target = target;
+ ch->comp_vector = ch_idx % ibdev->num_comp_vectors;
+ spin_lock_init(&ch->lock);
+ INIT_LIST_HEAD(&ch->free_tx);
+ ret = srp_new_cm_id(ch);
+ if (ret)
+ goto err_disconnect;
- ret = srp_create_ch_ib(ch);
- if (ret)
- goto err_disconnect;
+ ret = srp_create_ch_ib(ch);
+ if (ret)
+ goto err_disconnect;
- ret = srp_alloc_req_data(ch);
- if (ret)
- goto err_disconnect;
+ ret = srp_alloc_req_data(ch);
+ if (ret)
+ goto err_disconnect;
- ret = srp_connect_ch(ch, max_iu_len, multich);
- if (ret) {
- char dst[64];
-
- if (target->using_rdma_cm)
- snprintf(dst, sizeof(dst), "%pIS",
- &target->rdma_cm.dst);
- else
- snprintf(dst, sizeof(dst), "%pI6",
- target->ib_cm.orig_dgid.raw);
- shost_printk(KERN_ERR, target->scsi_host,
- PFX "Connection %d/%d to %s failed\n",
- ch_start + cpu_idx,
- target->ch_count, dst);
- if (node_idx == 0 && cpu_idx == 0) {
- goto free_ch;
- } else {
- srp_free_ch_ib(target, ch);
- srp_free_req_data(target, ch);
- target->ch_count = ch - target->ch;
- goto connected;
- }
- }
+ ret = srp_connect_ch(ch, max_iu_len, multich);
+ if (ret) {
+ char dst[64];
- multich = true;
- cpu_idx++;
+ if (target->using_rdma_cm)
+ snprintf(dst, sizeof(dst), "%pIS",
+ &target->rdma_cm.dst);
+ else
+ snprintf(dst, sizeof(dst), "%pI6",
+ target->ib_cm.orig_dgid.raw);
+ shost_printk(KERN_ERR, target->scsi_host,
+ PFX "Connection %d/%d to %s failed\n",
+ ch_idx,
+ target->ch_count, dst);
+ if (ch_idx == 0) {
+ goto free_ch;
+ } else {
+ srp_free_ch_ib(target, ch);
+ srp_free_req_data(target, ch);
+ target->ch_count = ch - target->ch;
+ goto connected;
+ }
}
- node_idx++;
+ multich = true;
}
connected:
--
2.30.0.4.g42936b2fde60
