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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-08-25 23:02:17 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-09-26 17:18:13 -0700 |
| commit | 8411b2debbd772b2dc156f06d7da73cdcbd08d35 (patch) | |
| tree | 45c9e15408dfc8bf48cc361be29bd83a72f150b7 /net | |
| parent | fd31b5dcb8c69c007705caa9dccdaa371f21b4f0 (diff) | |
| download | kernel-common-8411b2debbd772b2dc156f06d7da73cdcbd08d35.tar.gz kernel-common-8411b2debbd772b2dc156f06d7da73cdcbd08d35.tar.bz2 kernel-common-8411b2debbd772b2dc156f06d7da73cdcbd08d35.zip | |
tcp: fix three tcp sysctls tuning
[ Upstream commit c5ed63d66f24fd4f7089b5a6e087b0ce7202aa8e ]
As discovered by Anton Blanchard, current code to autotune
tcp_death_row.sysctl_max_tw_buckets, sysctl_tcp_max_orphans and
sysctl_max_syn_backlog makes little sense.
The bigger a page is, the less tcp_max_orphans is : 4096 on a 512GB
machine in Anton's case.
(tcp_hashinfo.bhash_size * sizeof(struct inet_bind_hashbucket))
is much bigger if spinlock debugging is on. Its wrong to select bigger
limits in this case (where kernel structures are also bigger)
bhash_size max is 65536, and we get this value even for small machines.
A better ground is to use size of ehash table, this also makes code
shorter and more obvious.
Based on a patch from Anton, and another from David.
Reported-and-tested-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp.c | 24 |
1 files changed, 7 insertions, 17 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index dfe12d6bad92..952ba943c77f 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3193,7 +3193,7 @@ void __init tcp_init(void) { struct sk_buff *skb = NULL; unsigned long nr_pages, limit; - int order, i, max_share; + int i, max_share, cnt; unsigned long jiffy = jiffies; BUILD_BUG_ON(sizeof(struct tcp_skb_cb) > sizeof(skb->cb)); @@ -3242,22 +3242,12 @@ void __init tcp_init(void) INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain); } - /* Try to be a bit smarter and adjust defaults depending - * on available memory. - */ - for (order = 0; ((1 << order) << PAGE_SHIFT) < - (tcp_hashinfo.bhash_size * sizeof(struct inet_bind_hashbucket)); - order++) - ; - if (order >= 4) { - tcp_death_row.sysctl_max_tw_buckets = 180000; - sysctl_tcp_max_orphans = 4096 << (order - 4); - sysctl_max_syn_backlog = 1024; - } else if (order < 3) { - tcp_death_row.sysctl_max_tw_buckets >>= (3 - order); - sysctl_tcp_max_orphans >>= (3 - order); - sysctl_max_syn_backlog = 128; - } + + cnt = tcp_hashinfo.ehash_mask + 1; + + tcp_death_row.sysctl_max_tw_buckets = cnt / 2; + sysctl_tcp_max_orphans = cnt / 2; + sysctl_max_syn_backlog = max(128, cnt / 256); /* Set the pressure threshold to be a fraction of global memory that * is up to 1/2 at 256 MB, decreasing toward zero with the amount of |