From: Nicholas Piggin <npiggin@gmail.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org
Subject: Re: [PATCH v3 4/4] powerpc/64s: idle ESL=0 stop can avoid MSR and save/restore overhead
Date: Wed, 30 Aug 2017 22:10:45 +1000 [thread overview]
Message-ID: <20170830221045.6fd10787@roar.ozlabs.ibm.com> (raw)
In-Reply-To: <87pobd1em0.fsf@concordia.ellerman.id.au>
On Wed, 30 Aug 2017 21:25:59 +1000
Michael Ellerman <mpe@ellerman.id.au> wrote:
> Nicholas Piggin <npiggin@gmail.com> writes:
>
> > When stop is executed with EC=ESL=0, it appears to execute like a
> > normal instruction (resuming from NIP when woken by interrupt).
> > So all the save/restore handling can be avoided completely. In
> > particular NV GPRs do not have to be saved, and MSR does not have
> > to be switched back to kernel MSR.
> >
> > So move the test for "lite" sleep states out to power9_idle_stop.
> >
> > Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> > ---
> > arch/powerpc/kernel/idle_book3s.S | 35 ++++++++++++++++++++++++-----------
> > 1 file changed, 24 insertions(+), 11 deletions(-)
>
> This is blowing up for me on mambo:
Oh this is a known bug in mambo that does not match the hardware.
You need >= Mambo.7.8.21, or this firmware patch to work around
the issue for old mambos.
mambo.git 58d3162f4d6204fc077ff4a6ba47e4d1e19d5120
https://lists.ozlabs.org/pipermail/skiboot/2017-August/008768.html
Thanks,
Nick
next prev parent reply other threads:[~2017-08-30 12:11 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-25 4:30 [PATCH v3 0/4] powerpc/64s: idle POWER9 stop improvements Nicholas Piggin
2017-08-25 4:30 ` [PATCH v3 1/4] KVM: PPC: Book3S HV: POWER9 does not require secondary thread management Nicholas Piggin
2017-08-28 11:49 ` Michael Ellerman
2017-08-29 0:13 ` Paul Mackerras
2017-08-31 11:36 ` [v3, " Michael Ellerman
2017-08-25 4:30 ` [PATCH v3 2/4] powerpc/64s: idle POWER9 can execute stop without a sync sequence Nicholas Piggin
2017-08-29 0:11 ` Paul Mackerras
2017-08-29 10:30 ` Michael Ellerman
2017-08-31 11:36 ` [v3, " Michael Ellerman
2017-08-25 4:30 ` [PATCH v3 3/4] powerpc/64s: idle POWER9 can execute stop in virtual mode Nicholas Piggin
2017-08-29 0:14 ` Paul Mackerras
2017-08-31 11:36 ` [v3, " Michael Ellerman
2017-08-25 4:30 ` [PATCH v3 4/4] powerpc/64s: idle ESL=0 stop can avoid MSR and save/restore overhead Nicholas Piggin
2017-08-29 0:20 ` Paul Mackerras
2017-08-29 1:39 ` Nicholas Piggin
2017-08-30 11:25 ` Michael Ellerman
2017-08-30 12:10 ` Nicholas Piggin [this message]
2017-09-01 9:39 ` Michael Ellerman
2017-09-20 13:56 ` Nicholas Piggin
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