From: Giovanni Gherdovich <ggherdovich@suse.cz>
To: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@suse.de>, Len Brown <lenb@kernel.org>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>
Cc: x86@kernel.org, linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org,
Mel Gorman <mgorman@techsingularity.net>,
Doug Smythies <dsmythies@telus.net>,
Like Xu <like.xu@linux.intel.com>,
Neil Rickert <nwr10cst-oslnx@yahoo.com>,
Chris Wilson <chris@chris-wilson.co.uk>,
Giovanni Gherdovich <ggherdovich@suse.cz>
Subject: [PATCH 2/4] x86, sched: Account for CPUs with less than 4 cores in freq. invariance
Date: Thu, 16 Apr 2020 07:47:43 +0200 [thread overview]
Message-ID: <20200416054745.740-3-ggherdovich@suse.cz> (raw)
In-Reply-To: <20200416054745.740-1-ggherdovich@suse.cz>
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@yahoo.com>
Reported-by: Like Xu <like.xu@linux.intel.com>
Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.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
next prev parent reply other threads:[~2020-04-16 5:48 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-16 5:47 [PATCH 0/4] Frequency invariance fixes for x86 Giovanni Gherdovich
2020-04-16 5:47 ` [PATCH 1/4] x86, sched: Bail out of frequency invariance if base frequency is unknown Giovanni Gherdovich
2020-04-16 6:41 ` Giovanni Gherdovich
2020-04-16 15:41 ` Rafael J. Wysocki
2020-04-22 17:15 ` Ricardo Neri
2020-04-23 8:06 ` Giovanni Gherdovich
2020-04-24 1:32 ` Ricardo Neri
2020-04-24 5:53 ` Giovanni Gherdovich
2020-04-22 21:20 ` [tip: sched/urgent] " tip-bot2 for Giovanni Gherdovich
2020-04-16 5:47 ` Giovanni Gherdovich [this message]
2020-04-16 15:26 ` [PATCH 2/4] x86, sched: Account for CPUs with less than 4 cores in freq. invariance Dave Kleikamp
2020-04-22 21:20 ` [tip: sched/urgent] " tip-bot2 for Giovanni Gherdovich
2020-04-16 5:47 ` [PATCH 3/4] x86, sched: Don't enable static key when starting secondary CPUs Giovanni Gherdovich
2020-04-22 21:20 ` [tip: sched/urgent] " tip-bot2 for Peter Zijlstra (Intel)
2020-04-16 5:47 ` [PATCH 4/4] x86, sched: Move check for CPU type to caller function Giovanni Gherdovich
2020-04-22 21:20 ` [tip: sched/urgent] " tip-bot2 for Giovanni Gherdovich
2020-04-16 7:20 ` [PATCH 0/4] Frequency invariance fixes for x86 Peter Zijlstra
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