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authorEric Dumazet <eric.dumazet@gmail.com>2010-11-19 20:49:59 +0300
committerDavid S. Miller <davem@davemloft.net>2010-11-19 20:49:59 +0300
commit93aaae2e01e57483256b7da05c9a7ebd65ad4686 (patch)
treeb3e4117bbf39814ef58ce1d012d977d2d5393c38 /net/core/timestamping.c
parent0a80410dc53cf68e56456bef1ca66949b87412f9 (diff)
downloadlinux-93aaae2e01e57483256b7da05c9a7ebd65ad4686.tar.xz
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 'net/core/timestamping.c')
-rw-r--r--net/core/timestamping.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/core/timestamping.c b/net/core/timestamping.c
index 0ae6c22da85b..dac7ed687f60 100644
--- a/net/core/timestamping.c
+++ b/net/core/timestamping.c
@@ -31,7 +31,7 @@ static unsigned int classify(struct sk_buff *skb)
if (likely(skb->dev &&
skb->dev->phydev &&
skb->dev->phydev->drv))
- return sk_run_filter(skb, ptp_filter, ARRAY_SIZE(ptp_filter));
+ return sk_run_filter(skb, ptp_filter);
else
return PTP_CLASS_NONE;
}