On 16 Aug 2005 15:15:35 +0200, Andi Kleen <[email protected]> wrote:
> However it disables preemption, which especially for bigger
> copies will probably make the low latency people unhappy.
In the copy loop,
+#ifdef CONFIG_PREEMPT
+ if ( (i%64)==0 ) {
+ MMX_RESTORE;
+ MMX_SAVE;
+ };
+#endif
It costs several hundred clocks (wow) every 4KB copy.
It kills throughput but it makes the low latency people smile.
So I make two APIs.
__copy_user_zeroing_nocache()
__copy_user_zeroing_inatomic_nocache()
The former is a low latency version and the other is a throughput version.
What do you think?
Regards,
Hiro
--
Hiro Yoshioka
mailto:hyoshiok at miraclelinux.com
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