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Date: Fri, 2 Feb 2018 15:08:17 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: Mel Gorman <mgorman@...hsingularity.net>,
Mike Galbraith <efault@....de>,
Matt Fleming <matt@...eblueprint.co.uk>,
LKML <linux-kernel@...r.kernel.org>,
srinivas.pandruvada@...ux.intel.com
Subject: Re: [PATCH 4/4] sched/fair: Use a recently used CPU as an idle
candidate and the basis for SIS
On Fri, Feb 02, 2018 at 01:46:47PM +0100, Peter Zijlstra wrote:
> +static void __intel_pstate_hwp_set_desired(int val)
> +{
> + u64 value;
> +
> + value = rdmsrl(MSR_HWP_REQUEST);
> + value &= ~GENMASK_ULL(23, 16);
> + value |= (val & 0xff) << 16;
> + wrmsrl(MSR_HWP_REQUEST, val);
> +}
Also, if we keep a software shadow of that MSR, we can avoid the
rdmsr, which might also help.
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