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/linux/arch/sparc/kernel/
H A Detrap_64.Sdiff a7159a87a3836f61a97882e671d2d66bbb96c62e Fri Aug 18 21:40:36 CEST 2017 Anthony Yznaga <anthony.yznaga@oracle.com> sparc64: speed up etrap/rtrap on NG2 and later processors

For many sun4v processor types, reading or writing a privileged register
has a latency of 40 to 70 cycles. Use a combination of the low-latency
allclean, otherw, normalw, and nop instructions in etrap and rtrap to
replace 2 rdpr and 5 wrpr instructions and improve etrap/rtrap
performance. allclean, otherw, and normalw are available on NG2 and
later processors.

The average ticks to execute the flush windows trap ("ta 0x3") with and
without this patch on select platforms:

CPU Not patched Patched % Latency Reduction

NG2 1762 1558 -11.58
NG4 3619 3204 -11.47
M7 3015 2624 -12.97
SPARC64-X 829 770 -7.12

Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
H A Drtrap_64.Sdiff a7159a87a3836f61a97882e671d2d66bbb96c62e Fri Aug 18 21:40:36 CEST 2017 Anthony Yznaga <anthony.yznaga@oracle.com> sparc64: speed up etrap/rtrap on NG2 and later processors

For many sun4v processor types, reading or writing a privileged register
has a latency of 40 to 70 cycles. Use a combination of the low-latency
allclean, otherw, normalw, and nop instructions in etrap and rtrap to
replace 2 rdpr and 5 wrpr instructions and improve etrap/rtrap
performance. allclean, otherw, and normalw are available on NG2 and
later processors.

The average ticks to execute the flush windows trap ("ta 0x3") with and
without this patch on select platforms:

CPU Not patched Patched % Latency Reduction

NG2 1762 1558 -11.58
NG4 3619 3204 -11.47
M7 3015 2624 -12.97
SPARC64-X 829 770 -7.12

Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
H A Dvmlinux.lds.Sdiff a7159a87a3836f61a97882e671d2d66bbb96c62e Fri Aug 18 21:40:36 CEST 2017 Anthony Yznaga <anthony.yznaga@oracle.com> sparc64: speed up etrap/rtrap on NG2 and later processors

For many sun4v processor types, reading or writing a privileged register
has a latency of 40 to 70 cycles. Use a combination of the low-latency
allclean, otherw, normalw, and nop instructions in etrap and rtrap to
replace 2 rdpr and 5 wrpr instructions and improve etrap/rtrap
performance. allclean, otherw, and normalw are available on NG2 and
later processors.

The average ticks to execute the flush windows trap ("ta 0x3") with and
without this patch on select platforms:

CPU Not patched Patched % Latency Reduction

NG2 1762 1558 -11.58
NG4 3619 3204 -11.47
M7 3015 2624 -12.97
SPARC64-X 829 770 -7.12

Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
/linux/arch/sparc/include/asm/
H A Dtrap_block.hdiff a7159a87a3836f61a97882e671d2d66bbb96c62e Fri Aug 18 21:40:36 CEST 2017 Anthony Yznaga <anthony.yznaga@oracle.com> sparc64: speed up etrap/rtrap on NG2 and later processors

For many sun4v processor types, reading or writing a privileged register
has a latency of 40 to 70 cycles. Use a combination of the low-latency
allclean, otherw, normalw, and nop instructions in etrap and rtrap to
replace 2 rdpr and 5 wrpr instructions and improve etrap/rtrap
performance. allclean, otherw, and normalw are available on NG2 and
later processors.

The average ticks to execute the flush windows trap ("ta 0x3") with and
without this patch on select platforms:

CPU Not patched Patched % Latency Reduction

NG2 1762 1558 -11.58
NG4 3619 3204 -11.47
M7 3015 2624 -12.97
SPARC64-X 829 770 -7.12

Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>