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authorChuck Lever <chuck.lever@oracle.com>2020-12-29 15:47:44 -0500
committerChuck Lever <chuck.lever@oracle.com>2021-01-25 09:36:28 -0500
commitdf971cd853c05778ae1175e8aeb80a04bb9d4be5 (patch)
tree90179b120aa5fcfcfacc44439ffbb0e2a1ae16f2 /net/sunrpc
parent59a00257c66c2d7b3db21245287711ea6c745e7c (diff)
svcrdma: Convert rdma_stat_recv to a per-CPU counter
Receives are frequent events. Avoid the overhead of a memory bus lock cycle for counting a value that is hardly every used. Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'net/sunrpc')
-rw-r--r--net/sunrpc/xprtrdma/svc_rdma.c55
-rw-r--r--net/sunrpc/xprtrdma/svc_rdma_recvfrom.c3
2 files changed, 52 insertions, 6 deletions
diff --git a/net/sunrpc/xprtrdma/svc_rdma.c b/net/sunrpc/xprtrdma/svc_rdma.c
index 1fc1d5cbeb9b..3e5e622bad81 100644
--- a/net/sunrpc/xprtrdma/svc_rdma.c
+++ b/net/sunrpc/xprtrdma/svc_rdma.c
@@ -63,7 +63,7 @@ unsigned int svcrdma_max_req_size = RPCRDMA_DEF_INLINE_THRESH;
static unsigned int min_max_inline = RPCRDMA_DEF_INLINE_THRESH;
static unsigned int max_max_inline = RPCRDMA_MAX_INLINE_THRESH;
-atomic_t rdma_stat_recv;
+struct percpu_counter svcrdma_stat_recv;
atomic_t rdma_stat_read;
atomic_t rdma_stat_write;
atomic_t rdma_stat_sq_starve;
@@ -110,6 +110,42 @@ static int read_reset_stat(struct ctl_table *table, int write,
return 0;
}
+enum {
+ SVCRDMA_COUNTER_BUFSIZ = sizeof(unsigned long long),
+};
+
+static int svcrdma_counter_handler(struct ctl_table *table, int write,
+ void *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct percpu_counter *stat = (struct percpu_counter *)table->data;
+ char tmp[SVCRDMA_COUNTER_BUFSIZ + 1];
+ int len;
+
+ if (write) {
+ percpu_counter_set(stat, 0);
+ return 0;
+ }
+
+ len = snprintf(tmp, SVCRDMA_COUNTER_BUFSIZ, "%lld\n",
+ percpu_counter_sum_positive(stat));
+ if (len >= SVCRDMA_COUNTER_BUFSIZ)
+ return -EFAULT;
+ len = strlen(tmp);
+ if (*ppos > len) {
+ *lenp = 0;
+ return 0;
+ }
+ len -= *ppos;
+ if (len > *lenp)
+ len = *lenp;
+ if (len)
+ memcpy(buffer, tmp, len);
+ *lenp = len;
+ *ppos += len;
+
+ return 0;
+}
+
static struct ctl_table_header *svcrdma_table_header;
static struct ctl_table svcrdma_parm_table[] = {
{
@@ -149,10 +185,10 @@ static struct ctl_table svcrdma_parm_table[] = {
},
{
.procname = "rdma_stat_recv",
- .data = &rdma_stat_recv,
- .maxlen = sizeof(atomic_t),
+ .data = &svcrdma_stat_recv,
+ .maxlen = SVCRDMA_COUNTER_BUFSIZ,
.mode = 0644,
- .proc_handler = read_reset_stat,
+ .proc_handler = svcrdma_counter_handler,
},
{
.procname = "rdma_stat_write",
@@ -230,15 +266,26 @@ static void svc_rdma_proc_cleanup(void)
return;
unregister_sysctl_table(svcrdma_table_header);
svcrdma_table_header = NULL;
+
+ percpu_counter_destroy(&svcrdma_stat_recv);
}
static int svc_rdma_proc_init(void)
{
+ int rc;
+
if (svcrdma_table_header)
return 0;
+ rc = percpu_counter_init(&svcrdma_stat_recv, 0, GFP_KERNEL);
+ if (rc)
+ goto out_err;
+
svcrdma_table_header = register_sysctl_table(svcrdma_root_table);
return 0;
+
+out_err:
+ return rc;
}
void svc_rdma_cleanup(void)
diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index cbdb71247755..7d14a74df716 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
@@ -845,8 +845,7 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
}
list_del(&ctxt->rc_list);
spin_unlock(&rdma_xprt->sc_rq_dto_lock);
-
- atomic_inc(&rdma_stat_recv);
+ percpu_counter_inc(&svcrdma_stat_recv);
svc_rdma_build_arg_xdr(rqstp, ctxt);