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authorEric Dumazet <dada1@cosmosbay.com>2007-12-24 20:57:56 -0800
committerDavid S. Miller <davem@davemloft.net>2008-01-28 15:00:05 -0800
commit21371f768bf7127ee45bfaadd17899df6a439e8f (patch)
tree91b5debf1d861a40c942a33f1286b70031a94305
parentb15c4bcd15741b31019379298edfca28dc78029d (diff)
[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 <dada1@cosmosbay.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/sock.h3
-rw-r--r--net/core/stream.c2
2 files changed, 3 insertions, 2 deletions
diff --git a/include/net/sock.h b/include/net/sock.h
index e178b49eefb..d27ba6fdd03 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 5586879bb9b..bf188ffdbdb 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 &&