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author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-11-19 17:49:59 (GMT) |
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committer | David S. Miller <davem@davemloft.net> | 2010-11-19 17:49:59 (GMT) |
commit | 93aaae2e01e57483256b7da05c9a7ebd65ad4686 (patch) | |
tree | b3e4117bbf39814ef58ce1d012d977d2d5393c38 /net/core/timestamping.c | |
parent | 0a80410dc53cf68e56456bef1ca66949b87412f9 (diff) | |
download | linux-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.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/core/timestamping.c b/net/core/timestamping.c index 0ae6c22..dac7ed6 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; } |