Re: [PATCH 00/16] Remove the ipv4 routing cache
From: Eric Dumazet <hidden>
Date: 2012-07-26 17:43:58
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
On Thu, 2012-07-26 at 19:36 +0200, Eric Dumazet wrote:
On Thu, 2012-07-26 at 19:31 +0200, Eric Dumazet wrote:quoted
On Thu, 2012-07-26 at 10:18 -0700, Alexander Duyck wrote:quoted
I tested this patch and it looks like it runs, but still has the same performance issue. I did some digging into the annotation for ip_route_intput_noref and it seems like the issue is that I am hitting the dst_hold call in __mkroute_input.David suggested a percpu cache. nh_rth_input would be allocated by alloc_percpu(struct dst *) I can work on this.Wait a minute, on input we should use the noref trick too.
Something like : (on top of latest David patch)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 7a591aa..d5d2ad1 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c@@ -1371,8 +1371,7 @@ static void ip_handle_martian_source(struct net_device *dev, static int __mkroute_input(struct sk_buff *skb, const struct fib_result *res, struct in_device *in_dev, - __be32 daddr, __be32 saddr, u32 tos, - struct rtable **result) + __be32 daddr, __be32 saddr, u32 tos) { struct rtable *rth; int err;
@@ -1423,7 +1422,7 @@ static int __mkroute_input(struct sk_buff *skb, if (!itag) { rth = FIB_RES_NH(*res).nh_rth_input; if (rt_cache_valid(rth)) { - dst_hold(&rth->dst); + skb_dst_set_noref(skb, &rth->dst); goto out; } do_cache = true;
@@ -1451,7 +1450,6 @@ static int __mkroute_input(struct sk_buff *skb, rt_set_nexthop(rth, daddr, res, NULL, res->fi, res->type, itag); out: - *result = rth; err = 0; cleanup: return err;
@@ -1463,21 +1461,13 @@ static int ip_mkroute_input(struct sk_buff *skb, struct in_device *in_dev, __be32 daddr, __be32 saddr, u32 tos) { - struct rtable *rth = NULL; - int err; - #ifdef CONFIG_IP_ROUTE_MULTIPATH if (res->fi && res->fi->fib_nhs > 1) fib_select_multipath(res); #endif /* create a routing cache entry */ - err = __mkroute_input(skb, res, in_dev, daddr, saddr, tos, &rth); - if (err) - return err; - - skb_dst_set(skb, &rth->dst); - return 0; + return __mkroute_input(skb, res, in_dev, daddr, saddr, tos); } /*