From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [DST]: shrinks sizeof(struct rtable) by 64 bytes on x86_64 Date: Tue, 22 Jan 2008 11:50:06 +0100 Message-ID: <20080122115006.82dbbff4.dada1@cosmosbay.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" To: David Miller Return-path: Received: from pfx2.jmh.fr ([194.153.89.55]:34217 "EHLO pfx2.jmh.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755003AbYAVKuP (ORCPT ); Tue, 22 Jan 2008 05:50:15 -0500 Sender: netdev-owner@vger.kernel.org List-ID: On x86_64, sizeof(struct rtable) is 0x148, which is rounded up to 0x180 bytes by SLAB allocator. We can reduce this to exactly 0x140 bytes, without alignment overhead, and store 12 struct rtable per PAGE instead of 10. rate_tokens is currently defined as an "unsigned long", while its content should not exceed 6*HZ. It can safely be converted to an unsigned int. Moving tclassid right after rate_tokens to fill the 4 bytes hole permits to save 8 bytes on 'struct dst_entry', which finally permits to save 8 bytes on 'struct rtable' Signed-off-by: Eric Dumazet diff --git a/include/net/dst.h b/include/net/dst.h index c45dcc3..e3ac7d0 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -56,7 +56,11 @@ struct dst_entry struct dst_entry *path; unsigned long rate_last; /* rate limiting for ICMP */ - unsigned long rate_tokens; + unsigned int rate_tokens; + +#ifdef CONFIG_NET_CLS_ROUTE + __u32 tclassid; +#endif struct neighbour *neighbour; struct hh_cache *hh; @@ -65,10 +69,6 @@ struct dst_entry int (*input)(struct sk_buff*); int (*output)(struct sk_buff*); -#ifdef CONFIG_NET_CLS_ROUTE - __u32 tclassid; -#endif - struct dst_ops *ops; unsigned long lastuse; diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index 7ed8c50..1dbe89c 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -275,18 +275,19 @@ static inline void icmp_xmit_unlock(void) #define XRLIM_BURST_FACTOR 6 int xrlim_allow(struct dst_entry *dst, int timeout) { - unsigned long now; + unsigned long now, token = dst->rate_tokens; int rc = 0; now = jiffies; - dst->rate_tokens += now - dst->rate_last; + token += now - dst->rate_last; dst->rate_last = now; - if (dst->rate_tokens > XRLIM_BURST_FACTOR * timeout) - dst->rate_tokens = XRLIM_BURST_FACTOR * timeout; - if (dst->rate_tokens >= timeout) { - dst->rate_tokens -= timeout; + if (token > XRLIM_BURST_FACTOR * timeout) + token = XRLIM_BURST_FACTOR * timeout; + if (token >= timeout) { + token -= timeout; rc = 1; } + dst->rate_tokens = token; return rc; }