From: Eric Dumazet Date: Tue, 25 Dec 2007 04:57:56 +0000 (-0800) Subject: [SOCK] Avoid divides in sk_stream_pages() and __sk_stream_mem_reclaim() X-Git-Tag: v2.6.25-rc1~1162^2~919 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=21371f768bf7127ee45bfaadd17899df6a439e8f;p=linux-2.6 [SOCK] Avoid divides in sk_stream_pages() and __sk_stream_mem_reclaim() sk_forward_alloc being signed, we should take care of divides by SK_STREAM_MEM_QUANTUM we do in sk_stream_pages() and __sk_stream_mem_reclaim() This patchs introduces SK_STREAM_MEM_QUANTUM_SHIFT, defined as ilog2(SK_STREAM_MEM_QUANTUM), to be able to use right shifts instead of plain divides. This should help compiler to choose right shifts instead of expensive divides (as seen with CONFIG_CC_OPTIMIZE_FOR_SIZE=y on x86) Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- diff --git a/include/net/sock.h b/include/net/sock.h index e178b49eef..d27ba6fdd0 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -716,10 +716,11 @@ extern void __sk_stream_mem_reclaim(struct sock *sk); extern int sk_stream_mem_schedule(struct sock *sk, int size, int kind); #define SK_STREAM_MEM_QUANTUM ((int)PAGE_SIZE) +#define SK_STREAM_MEM_QUANTUM_SHIFT ilog2(SK_STREAM_MEM_QUANTUM) static inline int sk_stream_pages(int amt) { - return DIV_ROUND_UP(amt, SK_STREAM_MEM_QUANTUM); + return (amt + SK_STREAM_MEM_QUANTUM - 1) >> SK_STREAM_MEM_QUANTUM_SHIFT; } static inline void sk_stream_mem_reclaim(struct sock *sk) diff --git a/net/core/stream.c b/net/core/stream.c index 5586879bb9..bf188ffdbd 100644 --- a/net/core/stream.c +++ b/net/core/stream.c @@ -196,7 +196,7 @@ EXPORT_SYMBOL(sk_stream_error); void __sk_stream_mem_reclaim(struct sock *sk) { - atomic_sub(sk->sk_forward_alloc / SK_STREAM_MEM_QUANTUM, + atomic_sub(sk->sk_forward_alloc >> SK_STREAM_MEM_QUANTUM_SHIFT, sk->sk_prot->memory_allocated); sk->sk_forward_alloc &= SK_STREAM_MEM_QUANTUM - 1; if (*sk->sk_prot->memory_pressure &&