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head/sys/amd64/amd64/support.S: unroll loop

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unroll the loop in ENTRY(pagezero)
	acc' to the submitter this results in a reproducible 1% perf
	improvement under buildworld like workload

	I validated correctness and run-testing, but not performance impact

Submitted by:	lidl@pix.net
Reviewed by:	adrian
PR:		199151
MFC After:	1 month
This commit is contained in:
Eitan Adler 2015-04-05 05:07:24 +00:00
parent 00e2f0a3cb
commit 7e937fbfc2
1 changed files with 5 additions and 1 deletions
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6
sys/amd64/amd64/support.S
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@ -73,7 +73,11 @@ ENTRY(pagezero)
movnti %rax,8(%rdi,%rdx)
movnti %rax,16(%rdi,%rdx)
movnti %rax,24(%rdi,%rdx)
addq $32,%rdx
movnti %rax,32(%rdi,%rdx)
movnti %rax,40(%rdi,%rdx)
movnti %rax,48(%rdi,%rdx)
movnti %rax,56(%rdi,%rdx)
addq $64,%rdx
jne 1b
sfence
POP_FRAME_POINTER