kernel_optimize_test/drivers/isdn/i4l
Eric Dumazet 93aaae2e01 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 57fe93b374
(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>
2010-11-19 09:49:59 -08:00
..
isdn_audio.c
isdn_audio.h
isdn_bsdcomp.c
isdn_common.c
isdn_common.h
isdn_concap.c drivers/isdn/i4l: Remove unnecessary casts of netdev_priv 2010-11-17 10:36:50 -08:00
isdn_concap.h
isdn_net.c drivers/isdn/i4l: Remove unnecessary casts of netdev_priv 2010-11-17 10:36:50 -08:00
isdn_net.h
isdn_ppp.c filter: optimize sk_run_filter 2010-11-19 09:49:59 -08:00
isdn_ppp.h
isdn_tty.c
isdn_tty.h
isdn_ttyfax.c
isdn_ttyfax.h
isdn_v110.c
isdn_v110.h
isdn_x25iface.c
isdn_x25iface.h
isdnhdlc.c
Kconfig
Makefile