Messages in this thread | | | Date | Thu, 12 Jan 2023 21:41:40 +0100 | From | Andrea Mayer <> | Subject | Re: [net-next v2] ipv6: remove max_size check inline with ipv4 |
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Hi Jon,
On Thu, 12 Jan 2023 12:25:32 +1100 Jon Maxwell <jmaxwell37@gmail.com> wrote:
> v2: Correct syntax error in net/ipv6/route.c > > In ip6_dst_gc() replace: > > if (entries > gc_thresh) > > With: > > if (entries > ops->gc_thresh) > > Sending Ipv6 packets in a loop via a raw socket triggers an issue where a > route is cloned by ip6_rt_cache_alloc() for each packet sent. This quickly > consumes the Ipv6 max_size threshold which defaults to 4096 resulting in > these warnings: > > [1] 99.187805] dst_alloc: 7728 callbacks suppressed > [2] Route cache is full: consider increasing sysctl net.ipv6.route.max_size. > . > . > [300] Route cache is full: consider increasing sysctl net.ipv6.route.max_size. > > When this happens the packet is dropped and sendto() gets a network is > unreachable error: > > # ./a.out -s > > remaining pkt 200557 errno 101 > remaining pkt 196462 errno 101 > . > . > remaining pkt 126821 errno 101 > > Implement David Aherns suggestion to remove max_size check seeing that Ipv6 > has a GC to manage memory usage. Ipv4 already does not check max_size. > > Here are some memory comparisons for Ipv4 vs Ipv6 with the patch: > > Test by running 5 instances of a program that sends UDP packets to a raw > socket 5000000 times. Compare Ipv4 and Ipv6 performance with a similar > program. > > Ipv4: >
is it supposed to be Ipv6, right?
Ciao, Andrea
> Before test: > > # grep -e Slab -e Free /proc/meminfo > MemFree: 29427108 kB > Slab: 237612 kB > > # grep dst_cache /proc/slabinfo > ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0 > xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0 > ip_dst_cache 2881 3990 192 42 2 : tunables 0 0 0 > > During test: > > # grep -e Slab -e Free /proc/meminfo > MemFree: 29417608 kB > Slab: 247712 kB > > # grep dst_cache /proc/slabinfo > ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0 > xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0 > ip_dst_cache 44394 44394 192 42 2 : tunables 0 0 0 > > After test: > > # grep -e Slab -e Free /proc/meminfo > MemFree: 29422308 kB > Slab: 238104 kB > > # grep dst_cache /proc/slabinfo > ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0 > xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0 > ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0 > > Ipv6 with patch: > > Errno 101 errors are not observed anymore with the patch. > > Before test: > > # grep -e Slab -e Free /proc/meminfo > MemFree: 29422308 kB > Slab: 238104 kB > > # grep dst_cache /proc/slabinfo > ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0 > xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0 > ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0 > > During Test: > > # grep -e Slab -e Free /proc/meminfo > MemFree: 29431516 kB > Slab: 240940 kB > > # grep dst_cache /proc/slabinfo > ip6_dst_cache 11980 12064 256 32 2 : tunables 0 0 0 > xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0 > ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0 > > After Test: > > # grep -e Slab -e Free /proc/meminfo > MemFree: 29441816 kB > Slab: 238132 kB > > # grep dst_cache /proc/slabinfo > ip6_dst_cache 1902 2432 256 32 2 : tunables 0 0 0 > xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0 > ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0 > > Tested-by: Andrea Mayer <andrea.mayer@uniroma2.it> > Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com> > --- > include/net/dst_ops.h | 2 +- > net/core/dst.c | 8 ++------ > net/ipv6/route.c | 13 +++++-------- > 3 files changed, 8 insertions(+), 15 deletions(-) > > diff --git a/include/net/dst_ops.h b/include/net/dst_ops.h > index 88ff7bb2bb9b..632086b2f644 100644 > --- a/include/net/dst_ops.h > +++ b/include/net/dst_ops.h > @@ -16,7 +16,7 @@ struct dst_ops { > unsigned short family; > unsigned int gc_thresh; > > - int (*gc)(struct dst_ops *ops); > + void (*gc)(struct dst_ops *ops); > struct dst_entry * (*check)(struct dst_entry *, __u32 cookie); > unsigned int (*default_advmss)(const struct dst_entry *); > unsigned int (*mtu)(const struct dst_entry *); > diff --git a/net/core/dst.c b/net/core/dst.c > index 6d2dd03dafa8..31c08a3386d3 100644 > --- a/net/core/dst.c > +++ b/net/core/dst.c > @@ -82,12 +82,8 @@ void *dst_alloc(struct dst_ops *ops, struct net_device *dev, > > if (ops->gc && > !(flags & DST_NOCOUNT) && > - dst_entries_get_fast(ops) > ops->gc_thresh) { > - if (ops->gc(ops)) { > - pr_notice_ratelimited("Route cache is full: consider increasing sysctl net.ipv6.route.max_size.\n"); > - return NULL; > - } > - } > + dst_entries_get_fast(ops) > ops->gc_thresh) > + ops->gc(ops); > > dst = kmem_cache_alloc(ops->kmem_cachep, GFP_ATOMIC); > if (!dst) > diff --git a/net/ipv6/route.c b/net/ipv6/route.c > index e74e0361fd92..b643dda68d31 100644 > --- a/net/ipv6/route.c > +++ b/net/ipv6/route.c > @@ -91,7 +91,7 @@ static struct dst_entry *ip6_negative_advice(struct dst_entry *); > static void ip6_dst_destroy(struct dst_entry *); > static void ip6_dst_ifdown(struct dst_entry *, > struct net_device *dev, int how); > -static int ip6_dst_gc(struct dst_ops *ops); > +static void ip6_dst_gc(struct dst_ops *ops); > > static int ip6_pkt_discard(struct sk_buff *skb); > static int ip6_pkt_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb); > @@ -3284,11 +3284,10 @@ struct dst_entry *icmp6_dst_alloc(struct net_device *dev, > return dst; > } > > -static int ip6_dst_gc(struct dst_ops *ops) > +static void ip6_dst_gc(struct dst_ops *ops) > { > struct net *net = container_of(ops, struct net, ipv6.ip6_dst_ops); > int rt_min_interval = net->ipv6.sysctl.ip6_rt_gc_min_interval; > - int rt_max_size = net->ipv6.sysctl.ip6_rt_max_size; > int rt_elasticity = net->ipv6.sysctl.ip6_rt_gc_elasticity; > int rt_gc_timeout = net->ipv6.sysctl.ip6_rt_gc_timeout; > unsigned long rt_last_gc = net->ipv6.ip6_rt_last_gc; > @@ -3296,11 +3295,10 @@ static int ip6_dst_gc(struct dst_ops *ops) > int entries; > > entries = dst_entries_get_fast(ops); > - if (entries > rt_max_size) > + if (entries > ops->gc_thresh) > entries = dst_entries_get_slow(ops); > > - if (time_after(rt_last_gc + rt_min_interval, jiffies) && > - entries <= rt_max_size) > + if (time_after(rt_last_gc + rt_min_interval, jiffies)) > goto out; > > fib6_run_gc(atomic_inc_return(&net->ipv6.ip6_rt_gc_expire), net, true); > @@ -3310,7 +3308,6 @@ static int ip6_dst_gc(struct dst_ops *ops) > out: > val = atomic_read(&net->ipv6.ip6_rt_gc_expire); > atomic_set(&net->ipv6.ip6_rt_gc_expire, val - (val >> rt_elasticity)); > - return entries > rt_max_size; > } > > static int ip6_nh_lookup_table(struct net *net, struct fib6_config *cfg, > @@ -6512,7 +6509,7 @@ static int __net_init ip6_route_net_init(struct net *net) > #endif > > net->ipv6.sysctl.flush_delay = 0; > - net->ipv6.sysctl.ip6_rt_max_size = 4096; > + net->ipv6.sysctl.ip6_rt_max_size = INT_MAX; > net->ipv6.sysctl.ip6_rt_gc_min_interval = HZ / 2; > net->ipv6.sysctl.ip6_rt_gc_timeout = 60*HZ; > net->ipv6.sysctl.ip6_rt_gc_interval = 30*HZ; > -- > 2.31.1
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