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Date:      Thu, 20 Nov 2003 15:40:58 -0800 (PST)
From:      Nate Lawson <nate@root.org>
To:        John Baldwin <jhb@FreeBSD.org>
Cc:        cvs-all@FreeBSD.org
Subject:   RE: cvs commit: src/sys/dev/acpica acpi.c acpi_cpu.c
Message-ID:  <20031120153849.H72721@root.org>
In-Reply-To: <XFMail.20031120112916.jhb@FreeBSD.org>
References:  <XFMail.20031120112916.jhb@FreeBSD.org>

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On Thu, 20 Nov 2003, John Baldwin wrote:
> On 20-Nov-2003 Nate Lawson wrote:
> > On Wed, 19 Nov 2003, John Baldwin wrote:
> >> One minor suggestion btw.  Could you fix the hw.acpi.cpu.cpu_cx_lowest
> >> to use the "C1", "C2", and "C3" strings for its user-visible interface
> >> instead of the direct integer?  Setting the value to C2 is a bit more
> >> intuitive than setting it to 1 to get C2.
> >
> > I considered this before, however Cx is really a type, not a given state.
> > There can be more than 3 sleep states.  For instance, the IBM R40 has C1,
> > C2, C3, and C3 (4 states).  An index was the only unique way I could
> > specify the states.  The transition latency is also unique but setting a
> > state to 182 to get the last C3 state is even worse from a user
> > perspective.
>
> Ah.  Maybe rename the sysctl/tunable to indicate that it is an index?

No good ideas over here.  Took me a while to even come up with
hw.acpi.cpu.cx_lowest.  You want to indicate higher states will be also
used as determined by the scheduling algorithm and that states with higher
indices provide more power savings but also more latency.  cx_lowest_idx
seems kinda lame.  Suggestions?

-Nate



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