Cpuidle stop state implementation has minor optimizations for P10
where hardware preserves more SPR registers compared to P9.
The current P9 driver works for P10, although does few extra
save-restores. P9 driver can provide the required power management
features like SMT thread folding and core level power savings
on a P10 platform.
Until the P10 stop driver is available, revert the commit which
allows for only P9 systems to utilize cpuidle and blocks all
idle stop states for P10.
Cpu idle states are enabled and tested on the P10 platform
with this fix.
This reverts commit 8747bf36f312356f8a295a0c39ff092d65ce75ae.
Fixes: 8747bf36f312 ("powerpc/powernv/idle: Replace CPU feature check with PVR check")
Signed-off-by: Pratik Rajesh Sampat <redacted>
---
@mpe: This revert would resolve a staging issue wherein the P10 stop
driver is not yet ready while cpuidle stop states need not be blocked
on 5.9 for Power10 systems which could cause SMT folding related
performance issues.
The P10 stop driver is in the works here:
https://lists.ozlabs.org/pipermail/linuxppc-dev/2020-August/216773.html
arch/powerpc/platforms/powernv/idle.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Le 26/08/2020 à 10:29, Pratik Rajesh Sampat a écrit :
quoted hunk
Cpuidle stop state implementation has minor optimizations for P10
where hardware preserves more SPR registers compared to P9.
The current P9 driver works for P10, although does few extra
save-restores. P9 driver can provide the required power management
features like SMT thread folding and core level power savings
on a P10 platform.
Until the P10 stop driver is available, revert the commit which
allows for only P9 systems to utilize cpuidle and blocks all
idle stop states for P10.
Cpu idle states are enabled and tested on the P10 platform
with this fix.
This reverts commit 8747bf36f312356f8a295a0c39ff092d65ce75ae.
Fixes: 8747bf36f312 ("powerpc/powernv/idle: Replace CPU feature check with PVR check")
Signed-off-by: Pratik Rajesh Sampat <redacted>
---
@mpe: This revert would resolve a staging issue wherein the P10 stop
driver is not yet ready while cpuidle stop states need not be blocked
on 5.9 for Power10 systems which could cause SMT folding related
performance issues.
The P10 stop driver is in the works here:
https://lists.ozlabs.org/pipermail/linuxppc-dev/2020-August/216773.html
arch/powerpc/platforms/powernv/idle.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Le 26/08/2020 à 10:29, Pratik Rajesh Sampat a écrit :
quoted
Cpuidle stop state implementation has minor optimizations for P10
where hardware preserves more SPR registers compared to P9.
The current P9 driver works for P10, although does few extra
save-restores. P9 driver can provide the required power management
features like SMT thread folding and core level power savings
on a P10 platform.
Until the P10 stop driver is available, revert the commit which
allows for only P9 systems to utilize cpuidle and blocks all
idle stop states for P10.
Cpu idle states are enabled and tested on the P10 platform
with this fix.
This reverts commit 8747bf36f312356f8a295a0c39ff092d65ce75ae.
Fixes: 8747bf36f312 ("powerpc/powernv/idle: Replace CPU feature check
with PVR check")
Signed-off-by: Pratik Rajesh Sampat <redacted>
---
@mpe: This revert would resolve a staging issue wherein the P10 stop
driver is not yet ready while cpuidle stop states need not be blocked
on 5.9 for Power10 systems which could cause SMT folding related
performance issues.
The P10 stop driver is in the works here:
https://lists.ozlabs.org/pipermail/linuxppc-dev/2020-August/216773.html
arch/powerpc/platforms/powernv/idle.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
return;
}
- if (pvr_version_is(PVR_POWER9))
+ if (cpu_has_feature(CPU_FTR_ARCH_300))
Why not something like:
if (pvr_version_is(PVR_POWER9) || pvr_version_is(PVR_POWER10))
pnv_power9_idle_init();
In order to use PVR_POWER10 I would need to define it under
arch/powerpc/include/asm/reg.h, which is not present in 5.9 yet.
However, if it okay with @mpe I could split out Nick's P10 stop driver
(https://lists.ozlabs.org/pipermail/linuxppc-dev/2020-August/216773.html)
into two parts:
1. This could include minimal code to introduce the P10 PVR and the
stop wrappers for it. Although this patch internally still calls into
the P9 path. This should gracefully fix the issue.
2. Then later in this patch we could introduce the p10 callback
methods as they are in Nick's series.
---
Thanks
Pratik
quoted
pnv_power9_idle_init();
for (i = 0; i < nr_pnv_idle_states; i++)
Cpuidle stop state implementation has minor optimizations for P10
where hardware preserves more SPR registers compared to P9.
The current P9 driver works for P10, although does few extra
save-restores. P9 driver can provide the required power management
features like SMT thread folding and core level power savings
on a P10 platform.
Until the P10 stop driver is available, revert the commit which
allows for only P9 systems to utilize cpuidle and blocks all
idle stop states for P10.
Cpu idle states are enabled and tested on the P10 platform
with this fix.
This reverts commit 8747bf36f312356f8a295a0c39ff092d65ce75ae.
Fixes: 8747bf36f312 ("powerpc/powernv/idle: Replace CPU feature check with PVR check")
Signed-off-by: Pratik Rajesh Sampat <redacted>
Reviewed-by: Vaidyanathan Srinivasan <redacted>
quoted hunk
---
@mpe: This revert would resolve a staging issue wherein the P10 stop
driver is not yet ready while cpuidle stop states need not be blocked
on 5.9 for Power10 systems which could cause SMT folding related
performance issues.
The P10 stop driver is in the works here:
https://lists.ozlabs.org/pipermail/linuxppc-dev/2020-August/216773.html
arch/powerpc/platforms/powernv/idle.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
This revert solves the stated problem and makes kernel v5.9 work
reasonable well on P10 with stop states which are required for SMT
mode changes.
Complete P10 driver has been in the works and will build on this fix
and complete the required platform support and optimizations.
--Vaidy
From: Michael Ellerman <mpe@ellerman.id.au> Date: 2020-08-27 06:07:50
Pratik Sampat [off-list ref] writes:
On 26/08/20 2:07 pm, Christophe Leroy wrote:
quoted
Le 26/08/2020 à 10:29, Pratik Rajesh Sampat a écrit :
quoted
Cpuidle stop state implementation has minor optimizations for P10
where hardware preserves more SPR registers compared to P9.
The current P9 driver works for P10, although does few extra
save-restores. P9 driver can provide the required power management
features like SMT thread folding and core level power savings
on a P10 platform.
Until the P10 stop driver is available, revert the commit which
allows for only P9 systems to utilize cpuidle and blocks all
idle stop states for P10.
Cpu idle states are enabled and tested on the P10 platform
with this fix.
This reverts commit 8747bf36f312356f8a295a0c39ff092d65ce75ae.
Fixes: 8747bf36f312 ("powerpc/powernv/idle: Replace CPU feature check
with PVR check")
Signed-off-by: Pratik Rajesh Sampat <redacted>
---
@mpe: This revert would resolve a staging issue wherein the P10 stop
driver is not yet ready while cpuidle stop states need not be blocked
on 5.9 for Power10 systems which could cause SMT folding related
performance issues.
The P10 stop driver is in the works here:
https://lists.ozlabs.org/pipermail/linuxppc-dev/2020-August/216773.html
arch/powerpc/platforms/powernv/idle.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
return;
}
- if (pvr_version_is(PVR_POWER9))
+ if (cpu_has_feature(CPU_FTR_ARCH_300))
Why not something like:
if (pvr_version_is(PVR_POWER9) || pvr_version_is(PVR_POWER10))
pnv_power9_idle_init();
In order to use PVR_POWER10 I would need to define it under
arch/powerpc/include/asm/reg.h, which is not present in 5.9 yet.
However, if it okay with @mpe I could split out Nick's P10 stop driver
(https://lists.ozlabs.org/pipermail/linuxppc-dev/2020-August/216773.html)
into two parts:
I'll just take this for now, it's the simplest option.
cheers
From: Michael Ellerman <hidden> Date: 2020-08-27 07:47:06
On Wed, 26 Aug 2020 13:59:18 +0530, Pratik Rajesh Sampat wrote:
Cpuidle stop state implementation has minor optimizations for P10
where hardware preserves more SPR registers compared to P9.
The current P9 driver works for P10, although does few extra
save-restores. P9 driver can provide the required power management
features like SMT thread folding and core level power savings
on a P10 platform.
[...]