Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=21371f768bf7127ee45bfaadd17899df6a439e8f
Commit: 21371f768bf7127ee45bfaadd17899df6a439e8f
Parent: b15c4bcd15741b31019379298edfca28dc78029d
Author: Eric Dumazet <[EMAIL PROTECTED]>
AuthorDate: Mon Dec 24 20:57:56 2007 -0800
Committer: David S. Miller <[EMAIL PROTECTED]>
CommitDate: Mon Jan 28 15:00:05 2008 -0800
[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 <[EMAIL PROTECTED]>
Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
---
include/net/sock.h | 3 ++-
net/core/stream.c | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index e178b49..d27ba6f 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 5586879..bf188ff 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 &&
-
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