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Message-Id: <20200416054745.740-3-ggherdovich@suse.cz>
Date: Thu, 16 Apr 2020 07:47:43 +0200
From: Giovanni Gherdovich <ggherdovich@...e.cz>
To: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Borislav Petkov <bp@...e.de>, Len Brown <lenb@...nel.org>,
"Rafael J . Wysocki" <rjw@...ysocki.net>
Cc: x86@...nel.org, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org,
Mel Gorman <mgorman@...hsingularity.net>,
Doug Smythies <dsmythies@...us.net>,
Like Xu <like.xu@...ux.intel.com>,
Neil Rickert <nwr10cst-oslnx@...oo.com>,
Chris Wilson <chris@...is-wilson.co.uk>,
Giovanni Gherdovich <ggherdovich@...e.cz>
Subject: [PATCH 2/4] x86, sched: Account for CPUs with less than 4 cores in freq. invariance
If a CPU has less than 4 physical cores, MSR_TURBO_RATIO_LIMIT will
rightfully report that the 4C turbo ratio is zero. In such cases, use the
1C turbo ratio instead for frequency invariance calculations.
Reported-by: Neil Rickert <nwr10cst-oslnx@...oo.com>
Reported-by: Like Xu <like.xu@...ux.intel.com>
Signed-off-by: Giovanni Gherdovich <ggherdovich@...e.cz>
Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance")
---
arch/x86/kernel/smpboot.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 3a318ec9bc17..5d346b70844b 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1945,18 +1945,23 @@ static bool skx_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq, int size)
static bool core_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq)
{
+ u64 msr;
int err;
err = rdmsrl_safe(MSR_PLATFORM_INFO, base_freq);
if (err)
return false;
- err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, turbo_freq);
+ err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, &msr);
if (err)
return false;
- *base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
- *turbo_freq = (*turbo_freq >> 24) & 0xFF; /* 4C turbo */
+ *base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
+ *turbo_freq = (msr >> 24) & 0xFF; /* 4C turbo */
+
+ /* The CPU may have less than 4 cores */
+ if (!*turbo_freq)
+ *turbo_freq = msr & 0xFF; /* 1C turbo */
return true;
}
--
2.16.4
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