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author | Chuck Lever <chuck.lever@oracle.com> | 2014-11-08 20:15:09 -0500 |
---|---|---|
committer | Anna Schumaker <Anna.Schumaker@Netapp.com> | 2014-11-25 16:22:15 -0500 |
commit | edef1297f33a4546559d905457b435a5ea160bab (patch) | |
tree | c14a3b6d62e72cb8b46a3a8cc09679b343831b49 | |
parent | 5d01410fe4d92081f349b013a2e7a95429e4f2c9 (diff) | |
download | op-kernel-dev-edef1297f33a4546559d905457b435a5ea160bab.zip op-kernel-dev-edef1297f33a4546559d905457b435a5ea160bab.tar.gz |
SUNRPC: serialize iostats updates
Occasionally mountstats reports a negative retransmission rate.
Ensure that two RPCs completing concurrently don't confuse the sums
in the transport's op_metrics array.
Since pNFS filelayout can invoke rpc_count_iostats() on another
transport from xprt_release(), we can't rely on simply holding the
transport_lock in xprt_release(). There's nothing for it but hard
serialization. One spin lock per RPC operation should make this as
painless as it can be.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
-rw-r--r-- | include/linux/sunrpc/metrics.h | 3 | ||||
-rw-r--r-- | net/sunrpc/stats.c | 21 |
2 files changed, 19 insertions, 5 deletions
diff --git a/include/linux/sunrpc/metrics.h b/include/linux/sunrpc/metrics.h index 1565bbe..eecb5a7 100644 --- a/include/linux/sunrpc/metrics.h +++ b/include/linux/sunrpc/metrics.h @@ -27,10 +27,13 @@ #include <linux/seq_file.h> #include <linux/ktime.h> +#include <linux/spinlock.h> #define RPC_IOSTATS_VERS "1.0" struct rpc_iostats { + spinlock_t om_lock; + /* * These counters give an idea about how many request * transmissions are required, on average, to complete that diff --git a/net/sunrpc/stats.c b/net/sunrpc/stats.c index 5453049..9711a15 100644 --- a/net/sunrpc/stats.c +++ b/net/sunrpc/stats.c @@ -116,7 +116,15 @@ EXPORT_SYMBOL_GPL(svc_seq_show); */ struct rpc_iostats *rpc_alloc_iostats(struct rpc_clnt *clnt) { - return kcalloc(clnt->cl_maxproc, sizeof(struct rpc_iostats), GFP_KERNEL); + struct rpc_iostats *stats; + int i; + + stats = kcalloc(clnt->cl_maxproc, sizeof(*stats), GFP_KERNEL); + if (stats) { + for (i = 0; i < clnt->cl_maxproc; i++) + spin_lock_init(&stats[i].om_lock); + } + return stats; } EXPORT_SYMBOL_GPL(rpc_alloc_iostats); @@ -135,20 +143,21 @@ EXPORT_SYMBOL_GPL(rpc_free_iostats); * rpc_count_iostats - tally up per-task stats * @task: completed rpc_task * @stats: array of stat structures - * - * Relies on the caller for serialization. */ void rpc_count_iostats(const struct rpc_task *task, struct rpc_iostats *stats) { struct rpc_rqst *req = task->tk_rqstp; struct rpc_iostats *op_metrics; - ktime_t delta; + ktime_t delta, now; if (!stats || !req) return; + now = ktime_get(); op_metrics = &stats[task->tk_msg.rpc_proc->p_statidx]; + spin_lock(&op_metrics->om_lock); + op_metrics->om_ops++; op_metrics->om_ntrans += req->rq_ntrans; op_metrics->om_timeouts += task->tk_timeouts; @@ -161,8 +170,10 @@ void rpc_count_iostats(const struct rpc_task *task, struct rpc_iostats *stats) op_metrics->om_rtt = ktime_add(op_metrics->om_rtt, req->rq_rtt); - delta = ktime_sub(ktime_get(), task->tk_start); + delta = ktime_sub(now, task->tk_start); op_metrics->om_execute = ktime_add(op_metrics->om_execute, delta); + + spin_unlock(&op_metrics->om_lock); } EXPORT_SYMBOL_GPL(rpc_count_iostats); |