From: Michael Ellerman <mpe@ellerman•id.au>
To: Vaidyanathan Srinivasan <svaidy@linux•vnet.ibm.com>
Cc: linuxppc-dev@lists•ozlabs.org,
Michael Neuling <mikey@neuling•org>,
Anton Blanchard <anton@samba•org>
Subject: Re: [PATCH] powerpc/powernv/idle: Round up latency and residency values
Date: Thu, 24 Aug 2017 20:28:19 +1000 [thread overview]
Message-ID: <877extw98c.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <20170823185841.25286-1-svaidy@linux.vnet.ibm.com>
Vaidyanathan Srinivasan <svaidy@linux•vnet.ibm.com> writes:
> On PowerNV platforms, firmware provides exit latency and
> target residency for each of the idle states in nano
> seconds. Cpuidle framework expects the values in micro
> seconds. Round up to nearest micro seconds to avoid errors
> in cases where the values are defined as fractional micro
> seconds.
>
> Default idle state of 'snooze' has exit latency of zero. If
> other states have fractional micro second exit latency, they
> would get rounded down to zero micro second and make cpuidle
> framework choose deeper idle state when snooze loop is the
> right choice.
>
> Reported-by: Anton Blanchard <anton@samba•org>
> Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux•vnet.ibm.com>
This sounds like a fairly bad bug, does it need a Fixes / Cc stable tag?
cheers
next prev parent reply other threads:[~2017-08-24 10:28 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-23 18:58 [PATCH] powerpc/powernv/idle: Round up latency and residency values Vaidyanathan Srinivasan
2017-08-24 4:35 ` Gautham R Shenoy
2017-08-24 10:28 ` Michael Ellerman [this message]
2017-08-24 13:07 ` Vaidyanathan Srinivasan
2017-11-14 11:12 ` Michael Ellerman
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