[PATCH v1 1/2] SUNRPC: Add trace event when alloc_pages_bulk() makes no progress

[PATCH v1 1/2] SUNRPC: Add trace event when alloc_pages_bulk() makes no progress

[Chuck Lever]

This is an operational low memory situation that needs to be
flagged. The new tracepoint records a timestamp and the nfsd thread
that failed to allocate pages.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 include/trace/events/sunrpc.h |   18 ++++++++++++++++++
 net/sunrpc/svc_xprt.c         |    1 +
 2 files changed, 19 insertions(+)

diff --git a/include/trace/events/sunrpc.h b/include/trace/events/sunrpc.h
index 2d04eb96d418..fb016308c185 100644
--- a/include/trace/events/sunrpc.h
+++ b/include/trace/events/sunrpc.h
@@ -1859,6 +1859,24 @@ TRACE_EVENT(svc_wake_up,
 	TP_printk("pid=%d", __entry->pid)
 );
 
+TRACE_EVENT(svc_alloc_arg_err,
+	TP_PROTO(
+		unsigned int pages
+	),
+
+	TP_ARGS(pages),
+
+	TP_STRUCT__entry(
+		__field(unsigned int, pages)
+	),
+
+	TP_fast_assign(
+		__entry->pages = pages;
+	),
+
+	TP_printk("pages=%u", __entry->pages)
+);
+
 TRACE_EVENT(svc_handle_xprt,
 	TP_PROTO(struct svc_xprt *xprt, int len),
 
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 6316bd2b8f37..1e99ba1b9d72 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -687,6 +687,7 @@ static int svc_alloc_arg(struct svc_rqst *rqstp)
 			set_current_state(TASK_RUNNING);
 			return -EINTR;
 		}
+		trace_svc_alloc_arg_err(pages);
 		schedule_timeout(msecs_to_jiffies(500));
 	}
 	rqstp->rq_page_end = &rqstp->rq_pages[pages];

[PATCH v1 2/2] SUNRPC: Capture value of xdr_buf::page_base

[Chuck Lever]

This value is usually zero, but will be non-zero more often in the
future. Knowing its value can be important diagnostic information.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 include/trace/events/sunrpc.h |   20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/include/trace/events/sunrpc.h b/include/trace/events/sunrpc.h
index fb016308c185..9ea59959a2fe 100644
--- a/include/trace/events/sunrpc.h
+++ b/include/trace/events/sunrpc.h
@@ -62,6 +62,7 @@ DECLARE_EVENT_CLASS(rpc_xdr_buf_class,
 		__field(size_t, head_len)
 		__field(const void *, tail_base)
 		__field(size_t, tail_len)
+		__field(unsigned int, page_base)
 		__field(unsigned int, page_len)
 		__field(unsigned int, msg_len)
 	),
@@ -74,14 +75,17 @@ DECLARE_EVENT_CLASS(rpc_xdr_buf_class,
 		__entry->head_len = xdr->head[0].iov_len;
 		__entry->tail_base = xdr->tail[0].iov_base;
 		__entry->tail_len = xdr->tail[0].iov_len;
+		__entry->page_base = xdr->page_base;
 		__entry->page_len = xdr->page_len;
 		__entry->msg_len = xdr->len;
 	),
 
-	TP_printk("task:%u@%u head=[%p,%zu] page=%u tail=[%p,%zu] len=%u",
+	TP_printk("task:%u@%u head=[%p,%zu] page=%u(%u) tail=[%p,%zu] len=%u",
 		__entry->task_id, __entry->client_id,
-		__entry->head_base, __entry->head_len, __entry->page_len,
-		__entry->tail_base, __entry->tail_len, __entry->msg_len
+		__entry->head_base, __entry->head_len,
+		__entry->page_len, __entry->page_base,
+		__entry->tail_base, __entry->tail_len,
+		__entry->msg_len
 	)
 );
 
@@ -1496,6 +1500,7 @@ DECLARE_EVENT_CLASS(svc_xdr_buf_class,
 		__field(size_t, head_len)
 		__field(const void *, tail_base)
 		__field(size_t, tail_len)
+		__field(unsigned int, page_base)
 		__field(unsigned int, page_len)
 		__field(unsigned int, msg_len)
 	),
@@ -1506,14 +1511,17 @@ DECLARE_EVENT_CLASS(svc_xdr_buf_class,
 		__entry->head_len = xdr->head[0].iov_len;
 		__entry->tail_base = xdr->tail[0].iov_base;
 		__entry->tail_len = xdr->tail[0].iov_len;
+		__entry->page_base = xdr->page_base;
 		__entry->page_len = xdr->page_len;
 		__entry->msg_len = xdr->len;
 	),
 
-	TP_printk("xid=0x%08x head=[%p,%zu] page=%u tail=[%p,%zu] len=%u",
+	TP_printk("xid=0x%08x head=[%p,%zu] page=%u(%u) tail=[%p,%zu] len=%u",
 		__entry->xid,
-		__entry->head_base, __entry->head_len, __entry->page_len,
-		__entry->tail_base, __entry->tail_len, __entry->msg_len
+		__entry->head_base, __entry->head_len,
+		__entry->page_len, __entry->page_base,
+		__entry->tail_base, __entry->tail_len,
+		__entry->msg_len
 	)
 );