2018-01-15 04:05:14

by Trond Myklebust

Subject: [PATCH 1/2] SUNRPC: Chunk reading of replies from the server

Read the TCP data in chunks of max 2MB so that we do not hog the
socket lock.

Signed-off-by: Trond Myklebust <[email protected]>
---
net/sunrpc/xprtsock.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 6d0cc3b8f932..620be573d78b 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -52,6 +52,8 @@

#include "sunrpc.h"

+#define RPC_TCP_READ_CHUNK_SZ (3*512*1024)
+
static void xs_close(struct rpc_xprt *xprt);
static void xs_tcp_set_socket_timeouts(struct rpc_xprt *xprt,
struct socket *sock);
@@ -1479,6 +1481,7 @@ static int xs_tcp_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb, uns
.offset = offset,
.count = len,
};
+ size_t ret;

dprintk("RPC: xs_tcp_data_recv started\n");
do {
@@ -1507,9 +1510,14 @@ static int xs_tcp_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb, uns
/* Skip over any trailing bytes on short reads */
xs_tcp_read_discard(transport, &desc);
} while (desc.count);
+ ret = len - desc.count;
+ if (ret < rd_desc->count)
+ rd_desc->count -= ret;
+ else
+ rd_desc->count = 0;
trace_xs_tcp_data_recv(transport);
dprintk("RPC: xs_tcp_data_recv done\n");
- return len - desc.count;
+ return ret;
}

static void xs_tcp_data_receive(struct sock_xprt *transport)
@@ -1517,7 +1525,6 @@ static void xs_tcp_data_receive(struct sock_xprt *transport)
struct rpc_xprt *xprt = &transport->xprt;
struct sock *sk;
read_descriptor_t rd_desc = {
- .count = 2*1024*1024,
.arg.data = xprt,
};
unsigned long total = 0;
@@ -1531,16 +1538,16 @@ static void xs_tcp_data_receive(struct sock_xprt *transport)

/* We use rd_desc to pass struct xprt to xs_tcp_data_recv */
for (loop = 0; loop < 64; loop++) {
+ rd_desc.count = RPC_TCP_READ_CHUNK_SZ;
lock_sock(sk);
read = tcp_read_sock(sk, &rd_desc, xs_tcp_data_recv);
- if (read <= 0) {
+ if (rd_desc.count != 0 || read < 0) {
clear_bit(XPRT_SOCK_DATA_READY, &transport->sock_state);
release_sock(sk);
break;
}
release_sock(sk);
total += read;
- rd_desc.count = 65536;
}
if (test_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))
queue_work(xprtiod_workqueue, &transport->recv_worker);
--
2.14.3

2018-01-15 04:05:15

by Trond Myklebust

Subject: [PATCH 2/2] SUNRPC: Add explicit rescheduling points in the receive path

When reading the reply from the server, insert an explicit
cond_resched() to avoid starving higher priority tasks.

Signed-off-by: Trond Myklebust <[email protected]>
---
net/sunrpc/xprtsock.c | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 620be573d78b..18803021f242 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1005,6 +1005,7 @@ static void xs_local_data_receive(struct sock_xprt *transport)
struct sock *sk;
int err;

+restart:
mutex_lock(&transport->recv_mutex);
sk = transport->inet;
if (sk == NULL)
@@ -1018,6 +1019,11 @@ static void xs_local_data_receive(struct sock_xprt *transport)
}
if (!test_and_clear_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))
break;
+ if (need_resched()) {
+ mutex_unlock(&transport->recv_mutex);
+ cond_resched();
+ goto restart;
+ }
}
out:
mutex_unlock(&transport->recv_mutex);
@@ -1096,6 +1102,7 @@ static void xs_udp_data_receive(struct sock_xprt *transport)
struct sock *sk;
int err;

+restart:
mutex_lock(&transport->recv_mutex);
sk = transport->inet;
if (sk == NULL)
@@ -1109,6 +1116,11 @@ static void xs_udp_data_receive(struct sock_xprt *transport)
}
if (!test_and_clear_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))
break;
+ if (need_resched()) {
+ mutex_unlock(&transport->recv_mutex);
+ cond_resched();
+ goto restart;
+ }
}
out:
mutex_unlock(&transport->recv_mutex);
@@ -1528,16 +1540,16 @@ static void xs_tcp_data_receive(struct sock_xprt *transport)
.arg.data = xprt,
};
unsigned long total = 0;
- int loop;
int read = 0;

+restart:
mutex_lock(&transport->recv_mutex);
sk = transport->inet;
if (sk == NULL)
goto out;

/* We use rd_desc to pass struct xprt to xs_tcp_data_recv */
- for (loop = 0; loop < 64; loop++) {
+ for (;;) {
rd_desc.count = RPC_TCP_READ_CHUNK_SZ;
lock_sock(sk);
read = tcp_read_sock(sk, &rd_desc, xs_tcp_data_recv);
@@ -1548,6 +1560,11 @@ static void xs_tcp_data_receive(struct sock_xprt *transport)
}
release_sock(sk);
total += read;
+ if (need_resched()) {
+ mutex_unlock(&transport->recv_mutex);
+ cond_resched();
+ goto restart;
+ }
}
if (test_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))
queue_work(xprtiod_workqueue, &transport->recv_worker);
--
2.14.3