diff options
| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-11-19 09:49:59 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-11-19 09:49:59 -0800 |
| commit | 93aaae2e01e57483256b7da05c9a7ebd65ad4686 (patch) | |
| tree | b3e4117bbf39814ef58ce1d012d977d2d5393c38 /drivers/net/ppp_generic.c | |
| parent | 0a80410dc53cf68e56456bef1ca66949b87412f9 (diff) | |
| download | lwn-93aaae2e01e57483256b7da05c9a7ebd65ad4686.tar.gz lwn-93aaae2e01e57483256b7da05c9a7ebd65ad4686.zip | |
filter: optimize sk_run_filter
Remove pc variable to avoid arithmetic to compute fentry at each filter
instruction. Jumps directly manipulate fentry pointer.
As the last instruction of filter[] is guaranteed to be a RETURN, and
all jumps are before the last instruction, we dont need to check filter
bounds (number of instructions in filter array) at each iteration, so we
remove it from sk_run_filter() params.
On x86_32 remove f_k var introduced in commit 57fe93b374a6b871
(filter: make sure filters dont read uninitialized memory)
Note : We could use a CONFIG_ARCH_HAS_{FEW|MANY}_REGISTERS in order to
avoid too many ifdefs in this code.
This helps compiler to use cpu registers to hold fentry and A
accumulator.
On x86_32, this saves 401 bytes, and more important, sk_run_filter()
runs much faster because less register pressure (One less conditional
branch per BPF instruction)
# size net/core/filter.o net/core/filter_pre.o
text data bss dec hex filename
2948 0 0 2948 b84 net/core/filter.o
3349 0 0 3349 d15 net/core/filter_pre.o
on x86_64 :
# size net/core/filter.o net/core/filter_pre.o
text data bss dec hex filename
5173 0 0 5173 1435 net/core/filter.o
5224 0 0 5224 1468 net/core/filter_pre.o
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ppp_generic.c')
| -rw-r--r-- | drivers/net/ppp_generic.c | 12 |
1 files changed, 4 insertions, 8 deletions
diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c index 09cf56d0416a..0c91598ae280 100644 --- a/drivers/net/ppp_generic.c +++ b/drivers/net/ppp_generic.c @@ -1136,8 +1136,7 @@ ppp_send_frame(struct ppp *ppp, struct sk_buff *skb) a four-byte PPP header on each packet */ *skb_push(skb, 2) = 1; if (ppp->pass_filter && - sk_run_filter(skb, ppp->pass_filter, - ppp->pass_len) == 0) { + sk_run_filter(skb, ppp->pass_filter) == 0) { if (ppp->debug & 1) printk(KERN_DEBUG "PPP: outbound frame not passed\n"); kfree_skb(skb); @@ -1145,8 +1144,7 @@ ppp_send_frame(struct ppp *ppp, struct sk_buff *skb) } /* if this packet passes the active filter, record the time */ if (!(ppp->active_filter && - sk_run_filter(skb, ppp->active_filter, - ppp->active_len) == 0)) + sk_run_filter(skb, ppp->active_filter) == 0)) ppp->last_xmit = jiffies; skb_pull(skb, 2); #else @@ -1758,8 +1756,7 @@ ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb) *skb_push(skb, 2) = 0; if (ppp->pass_filter && - sk_run_filter(skb, ppp->pass_filter, - ppp->pass_len) == 0) { + sk_run_filter(skb, ppp->pass_filter) == 0) { if (ppp->debug & 1) printk(KERN_DEBUG "PPP: inbound frame " "not passed\n"); @@ -1767,8 +1764,7 @@ ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb) return; } if (!(ppp->active_filter && - sk_run_filter(skb, ppp->active_filter, - ppp->active_len) == 0)) + sk_run_filter(skb, ppp->active_filter) == 0)) ppp->last_recv = jiffies; __skb_pull(skb, 2); } else |