From 5a0950c27236dc6f6a3e9d13259c1a2e89fd1cf7 Mon Sep 17 00:00:00 2001 From: Jon Paul Maloy Date: Tue, 16 Aug 2016 11:53:51 -0400 Subject: [PATCH] tipc: ensure that link congestion and wakeup use same criteria When a link is attempted woken up after congestion, it uses a different, more generous criteria than when it was originally declared congested. This has the effect that the link, and the sending process, sometimes will be woken up unnecessarily, just to immediately return to congestion when it turns out there is not not enough space in its send queue to host the pending message. This is a waste of CPU cycles. We now change the function link_prepare_wakeup() to use exactly the same criteria as tipc_link_xmit(). However, since we are now excluding the window limit from the wakeup calculation, and the current backlog limit for the lowest level is too small to house even a single maximum-size message, we have to expand this limit. We do this by evaluating an alternative, minimum value during the setting of the importance limits. Acked-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller --- net/tipc/link.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/net/tipc/link.c b/net/tipc/link.c index 877d94f34814..2c6e1b9e024b 100644 --- a/net/tipc/link.c +++ b/net/tipc/link.c @@ -807,7 +807,7 @@ void link_prepare_wakeup(struct tipc_link *l) skb_queue_walk_safe(&l->wakeupq, skb, tmp) { imp = TIPC_SKB_CB(skb)->chain_imp; - lim = l->window + l->backlog[imp].limit; + lim = l->backlog[imp].limit; pnd[imp] += TIPC_SKB_CB(skb)->chain_sz; if ((pnd[imp] + l->backlog[imp].len) >= lim) break; @@ -873,9 +873,11 @@ int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list, struct sk_buff *skb, *_skb, *bskb; /* Match msg importance against this and all higher backlog limits: */ - for (i = imp; i <= TIPC_SYSTEM_IMPORTANCE; i++) { - if (unlikely(l->backlog[i].len >= l->backlog[i].limit)) - return link_schedule_user(l, list); + if (!skb_queue_empty(backlogq)) { + for (i = imp; i <= TIPC_SYSTEM_IMPORTANCE; i++) { + if (unlikely(l->backlog[i].len >= l->backlog[i].limit)) + return link_schedule_user(l, list); + } } if (unlikely(msg_size(hdr) > mtu)) { skb_queue_purge(list); @@ -1692,10 +1694,10 @@ void tipc_link_set_queue_limits(struct tipc_link *l, u32 win) int max_bulk = TIPC_MAX_PUBLICATIONS / (l->mtu / ITEM_SIZE); l->window = win; - l->backlog[TIPC_LOW_IMPORTANCE].limit = win / 2; - l->backlog[TIPC_MEDIUM_IMPORTANCE].limit = win; - l->backlog[TIPC_HIGH_IMPORTANCE].limit = win / 2 * 3; - l->backlog[TIPC_CRITICAL_IMPORTANCE].limit = win * 2; + l->backlog[TIPC_LOW_IMPORTANCE].limit = max_t(u16, 50, win); + l->backlog[TIPC_MEDIUM_IMPORTANCE].limit = max_t(u16, 100, win * 2); + l->backlog[TIPC_HIGH_IMPORTANCE].limit = max_t(u16, 150, win * 3); + l->backlog[TIPC_CRITICAL_IMPORTANCE].limit = max_t(u16, 200, win * 4); l->backlog[TIPC_SYSTEM_IMPORTANCE].limit = max_bulk; } -- 2.30.2