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net: sched: use no more than one page in struct fw_head

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In commit b4e9b520ca ("[NET_SCHED]: Add mask support to fwmark
classifier") Patrick added an u32 field in fw_head, making it slightly
bigger than one page.

Lets use 256 slots to make fw_hash() more straight forward, and move
@mask to the beginning of the structure as we often use a small number
of skb->mark. @mask and first hash buckets share the same cache line.

This brings back the memory usage to less than 4000 bytes, and permits
John to add a rcu_head at the end of the structure later without any
worry.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Thomas Graf <tgraf@suug.ch>
Cc: John Fastabend <john.fastabend@gmail.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2014-03-17 20:20:49 -07:00 committed by David S. Miller
parent 995dca4ce9
commit d37d8ac17d
1 changed files with 7 additions and 26 deletions
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33
net/sched/cls_fw.c
View file

@ -29,11 +29,11 @@
#include <net/act_api.h> #include <net/act_api.h>
#include <net/pkt_cls.h> #include <net/pkt_cls.h>
#define HTSIZE (PAGE_SIZE/sizeof(struct fw_filter *)) #define HTSIZE 256
struct fw_head { struct fw_head {
struct fw_filter *ht[HTSIZE]; u32 mask;
u32 mask; struct fw_filter *ht[HTSIZE];
}; };
struct fw_filter { struct fw_filter {
@ -46,30 +46,11 @@ struct fw_filter {
struct tcf_exts exts; struct tcf_exts exts;
}; };
static inline int fw_hash(u32 handle) static u32 fw_hash(u32 handle)
{ {
if (HTSIZE == 4096) handle ^= (handle >> 16);
return ((handle >> 24) & 0xFFF) ^ handle ^= (handle >> 8);
((handle >> 12) & 0xFFF) ^ return handle % HTSIZE;
(handle & 0xFFF);
else if (HTSIZE == 2048)
return ((handle >> 22) & 0x7FF) ^
((handle >> 11) & 0x7FF) ^
(handle & 0x7FF);
else if (HTSIZE == 1024)
return ((handle >> 20) & 0x3FF) ^
((handle >> 10) & 0x3FF) ^
(handle & 0x3FF);
else if (HTSIZE == 512)
return (handle >> 27) ^
((handle >> 18) & 0x1FF) ^
((handle >> 9) & 0x1FF) ^
(handle & 0x1FF);
else if (HTSIZE == 256) {
u8 *t = (u8 *) &handle;
return t[0] ^ t[1] ^ t[2] ^ t[3];
} else
return handle & (HTSIZE - 1);
} }
static int fw_classify(struct sk_buff *skb, const struct tcf_proto *tp, static int fw_classify(struct sk_buff *skb, const struct tcf_proto *tp,