Author: Ingo Molnar <mingo@xxxxxxx>
AuthorDate: Wed, 25 Feb 2009 08:22:20 +0100
Commit: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 25 Feb 2009 10:20:05 +0100
x86: usercopy: check for total size when deciding non-temporal cutoff
Impact: make more types of copies non-temporal
This change makes the following simple fix:
30d697f: x86: fix performance regression in write() syscall
A bit more sophisticated: we check the 'total' number of bytes
written to decide whether to copy in a cached or a non-temporal
way.
This will for example cause the tail (modulo 4096 bytes) chunk
of a large write() to be non-temporal too - not just the page-sized
chunks.
Cc: Salman Qazi <sqazi@xxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
arch/x86/include/asm/uaccess_64.h | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index a748253..dcaa040 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -198,7 +198,7 @@ static inline int __copy_from_user_nocache(void *dst, const void __user *src,
* non-temporal stores here. Smaller writes get handled
* via regular __copy_from_user():
*/
- if (likely(size >= PAGE_SIZE))
+ if (likely(total >= PAGE_SIZE))
return __copy_user_nocache(dst, src, size, 1);
else
return __copy_from_user(dst, src, size);
@@ -207,7 +207,7 @@ static inline int __copy_from_user_nocache(void *dst, const void __user *src,
static inline int __copy_from_user_inatomic_nocache(void *dst,
const void __user *src, unsigned size, unsigned total)
{
- if (likely(size >= PAGE_SIZE))
+ if (likely(total >= PAGE_SIZE))
return __copy_user_nocache(dst, src, size, 0);
else
return __copy_from_user_inatomic(dst, src, size);
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|