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Message-ID: <1515440080-27377-10-git-send-email-jon.maloy@ericsson.com>
Date: Mon, 8 Jan 2018 20:34:40 +0100
From: Jon Maloy <jon.maloy@...csson.com>
To: <davem@...emloft.net>, <netdev@...r.kernel.org>
CC: <mohan.krishna.ghanta.krishnamurthy@...csson.com>,
<tung.q.nguyen@...tech.com.au>, <hoang.h.le@...tech.com.au>,
<jon.maloy@...csson.com>, <canh.d.luu@...tech.com.au>,
<ying.xue@...driver.com>, <tipc-discussion@...ts.sourceforge.net>
Subject: [net-next 9/9] tipc: improve poll() for group member socket
The current criteria for returning POLLOUT from a group member socket is
too simplistic. It basically returns POLLOUT as soon as the group has
external destinations, something obviously leading to a lot of spinning
during destination congestion situations. At the same time, the internal
congestion handling is unnecessarily complex.
We now change this as follows.
- We introduce an 'open' flag in struct tipc_group. This flag is used
only to help poll() get the setting of POLLOUT right, and *not* for
congeston handling as such. This means that a user can choose to
ignore an EAGAIN for a destination and go on sending messages to
other destinations in the group if he wants to.
- The flag is set to false every time we return EAGAIN on a send call.
- The flag is set to true every time any member, i.e., not necessarily
the member that caused EAGAIN, is removed from the small_win list.
- We remove the group member 'usr_pending' flag. The size of the send
window and presence in the 'small_win' list is sufficient criteria
for recognizing congestion.
This solution seems to be a reasonable compromise between 'anycast',
which is normally not waiting for POLLOUT for a specific destination,
and the other three send modes, which are.
Acked-by: Ying Xue <ying.xue@...driver.com>
Signed-off-by: Jon Maloy <jon.maloy@...csson.com>
---
net/tipc/group.c | 64 +++++++++++++++++++++++++++++++------------------------
net/tipc/group.h | 2 +-
net/tipc/socket.c | 5 ++---
3 files changed, 39 insertions(+), 32 deletions(-)
diff --git a/net/tipc/group.c b/net/tipc/group.c
index 1908773..497ee34 100644
--- a/net/tipc/group.c
+++ b/net/tipc/group.c
@@ -74,7 +74,6 @@ struct tipc_member {
u16 bc_rcv_nxt;
u16 bc_syncpt;
u16 bc_acked;
- bool usr_pending;
};
struct tipc_group {
@@ -96,11 +95,27 @@ struct tipc_group {
u16 bc_ackers;
bool loopback;
bool events;
+ bool open;
};
static void tipc_group_proto_xmit(struct tipc_group *grp, struct tipc_member *m,
int mtyp, struct sk_buff_head *xmitq);
+bool tipc_group_is_open(struct tipc_group *grp)
+{
+ return grp->open;
+}
+
+static void tipc_group_open(struct tipc_member *m, bool *wakeup)
+{
+ *wakeup = false;
+ if (list_empty(&m->small_win))
+ return;
+ list_del_init(&m->small_win);
+ m->group->open = true;
+ *wakeup = true;
+}
+
static void tipc_group_decr_active(struct tipc_group *grp,
struct tipc_member *m)
{
@@ -406,20 +421,20 @@ bool tipc_group_cong(struct tipc_group *grp, u32 dnode, u32 dport,
int adv, state;
m = tipc_group_find_dest(grp, dnode, dport);
- *mbr = m;
- if (!m)
+ if (!tipc_group_is_receiver(m)) {
+ *mbr = NULL;
return false;
- if (m->usr_pending)
- return true;
+ }
+ *mbr = m;
+
if (m->window >= len)
return false;
- m->usr_pending = true;
+
+ grp->open = false;
/* If not fully advertised, do it now to prevent mutual blocking */
adv = m->advertised;
state = m->state;
- if (state < MBR_JOINED)
- return true;
if (state == MBR_JOINED && adv == ADV_IDLE)
return true;
if (state == MBR_ACTIVE && adv == ADV_ACTIVE)
@@ -437,9 +452,10 @@ bool tipc_group_bc_cong(struct tipc_group *grp, int len)
struct tipc_member *m = NULL;
/* If prev bcast was replicast, reject until all receivers have acked */
- if (grp->bc_ackers)
+ if (grp->bc_ackers) {
+ grp->open = false;
return true;
-
+ }
if (list_empty(&grp->small_win))
return false;
@@ -754,9 +770,7 @@ void tipc_group_proto_rcv(struct tipc_group *grp, bool *usr_wakeup,
/* Member can be taken into service */
m->state = MBR_JOINED;
- *usr_wakeup = true;
- m->usr_pending = false;
- list_del_init(&m->small_win);
+ tipc_group_open(m, usr_wakeup);
tipc_group_update_member(m, 0);
tipc_group_proto_xmit(grp, m, GRP_ADV_MSG, xmitq);
tipc_group_create_event(grp, m, TIPC_PUBLISHED,
@@ -767,8 +781,7 @@ void tipc_group_proto_rcv(struct tipc_group *grp, bool *usr_wakeup,
return;
m->bc_syncpt = msg_grp_bc_syncpt(hdr);
list_del_init(&m->list);
- list_del_init(&m->small_win);
- *usr_wakeup = true;
+ tipc_group_open(m, usr_wakeup);
tipc_group_decr_active(grp, m);
m->state = MBR_LEAVING;
tipc_group_create_event(grp, m, TIPC_WITHDRAWN,
@@ -778,26 +791,25 @@ void tipc_group_proto_rcv(struct tipc_group *grp, bool *usr_wakeup,
if (!m)
return;
m->window += msg_adv_win(hdr);
- *usr_wakeup = m->usr_pending;
- m->usr_pending = false;
- list_del_init(&m->small_win);
+ tipc_group_open(m, usr_wakeup);
return;
case GRP_ACK_MSG:
if (!m)
return;
m->bc_acked = msg_grp_bc_acked(hdr);
if (--grp->bc_ackers)
- break;
+ return;
+ list_del_init(&m->small_win);
+ m->group->open = true;
*usr_wakeup = true;
- m->usr_pending = false;
+ tipc_group_update_member(m, 0);
return;
case GRP_RECLAIM_MSG:
if (!m)
return;
- *usr_wakeup = m->usr_pending;
- m->usr_pending = false;
tipc_group_proto_xmit(grp, m, GRP_REMIT_MSG, xmitq);
m->window = ADV_IDLE;
+ tipc_group_open(m, usr_wakeup);
return;
case GRP_REMIT_MSG:
if (!m || m->state != MBR_RECLAIMING)
@@ -883,9 +895,7 @@ void tipc_group_member_evt(struct tipc_group *grp,
/* Member can be taken into service */
m->instance = instance;
m->state = MBR_JOINED;
- *usr_wakeup = true;
- m->usr_pending = false;
- list_del_init(&m->small_win);
+ tipc_group_open(m, usr_wakeup);
tipc_group_update_member(m, 0);
tipc_group_proto_xmit(grp, m, GRP_JOIN_MSG, xmitq);
tipc_group_create_event(grp, m, TIPC_PUBLISHED,
@@ -895,12 +905,10 @@ void tipc_group_member_evt(struct tipc_group *grp,
if (!m)
break;
- *usr_wakeup = true;
- m->usr_pending = false;
tipc_group_decr_active(grp, m);
m->state = MBR_LEAVING;
list_del_init(&m->list);
- list_del_init(&m->small_win);
+ tipc_group_open(m, usr_wakeup);
/* Only send event if no LEAVE message can be expected */
if (!tipc_node_is_up(net, node))
diff --git a/net/tipc/group.h b/net/tipc/group.h
index dee7947..f4a596e 100644
--- a/net/tipc/group.h
+++ b/net/tipc/group.h
@@ -67,9 +67,9 @@ void tipc_group_update_bc_members(struct tipc_group *grp, int len, bool ack);
bool tipc_group_cong(struct tipc_group *grp, u32 dnode, u32 dport,
int len, struct tipc_member **m);
bool tipc_group_bc_cong(struct tipc_group *grp, int len);
+bool tipc_group_is_open(struct tipc_group *grp);
void tipc_group_update_rcv_win(struct tipc_group *grp, int blks, u32 node,
u32 port, struct sk_buff_head *xmitq);
u16 tipc_group_bc_snd_nxt(struct tipc_group *grp);
void tipc_group_update_member(struct tipc_member *m, int len);
-int tipc_group_size(struct tipc_group *grp);
#endif
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index b24dab3..4660a5b 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -736,9 +736,8 @@ static unsigned int tipc_poll(struct file *file, struct socket *sock,
revents |= POLLIN | POLLRDNORM;
break;
case TIPC_OPEN:
- if (!grp || tipc_group_size(grp))
- if (!tsk->cong_link_cnt)
- revents |= POLLOUT;
+ if ((!grp || tipc_group_is_open(grp)) && !tsk->cong_link_cnt)
+ revents |= POLLOUT;
if (!tipc_sk_type_connectionless(sk))
break;
if (skb_queue_empty(&sk->sk_receive_queue))
--
2.1.4
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