Author: mjg
Date: Thu Aug 11 09:30:25 2016
New Revision: 303954
URL: https://svnweb.freebsd.org/changeset/base/303954
Log:
MFC r303583:
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.
Approved by: re (gjb)
Modified:
stable/11/sys/amd64/amd64/support.S
Directory Properties:
stable/11/ (props changed)
Modified: stable/11/sys/amd64/amd64/support.S
==============================================================================
--- stable/11/sys/amd64/amd64/support.S Thu Aug 11 09:28:49 2016
(r303953)
+++ stable/11/sys/amd64/amd64/support.S Thu Aug 11 09:30:25 2016
(r303954)
@@ -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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