Author: mjg
Date: Sun Jul 31 11:34:08 2016
New Revision: 303583
URL: https://svnweb.freebsd.org/changeset/base/303583
Log:
amd64: implement pagezero using rep stos
The current implementation uses non-temporal writes. This turns out to
be detrimental to performance if the page is used shortly after, which
is the typical case with page faults.
Switch to rep stos.
Reviewed by: kib
MFC after: 1 week
Modified:
head/sys/amd64/amd64/support.S
Modified: head/sys/amd64/amd64/support.S
==============================================================================
--- head/sys/amd64/amd64/support.S Sun Jul 31 10:37:09 2016
(r303582)
+++ head/sys/amd64/amd64/support.S Sun Jul 31 11:34:08 2016
(r303583)
@@ -64,17 +64,10 @@ END(bzero)
/* Address: %rdi */
ENTRY(pagezero)
PUSH_FRAME_POINTER
- movq $-PAGE_SIZE,%rdx
- subq %rdx,%rdi
+ movq $PAGE_SIZE/8,%rcx
xorl %eax,%eax
-1:
- movnti %rax,(%rdi,%rdx)
- movnti %rax,8(%rdi,%rdx)
- movnti %rax,16(%rdi,%rdx)
- movnti %rax,24(%rdi,%rdx)
- addq $32,%rdx
- jne 1b
- sfence
+ rep
+ stosq
POP_FRAME_POINTER
ret
END(pagezero)
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