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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,
	Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Giovanni Gherdovich <ggherdovich@suse.cz>
Subject: [PATCH 0/2] More frequency invariance fixes for x86
Date: Tue, 28 Apr 2020 15:24:48 +0200
Message-ID: <20200428132450.24901-1-ggherdovich@suse.cz> (raw)

Patch 1/2 prevents a division by zero in case the product
"delta_MPERF * arch_max_freq_ratio" overflows u64, as suggested by Linus at [1].
This patch supersedes the version at [2], as it also disables frequency
invariance when that overflow happens.

Patch 2/2 implements the recommendation by Ricardo Neri to check for an all
zero MSR_TURBO_RATIO_LIMIT and disable freq invariance in that case too.

[1] https://lore.kernel.org/lkml/CAHk-=wiX+NT2yxtdPszH9U_S96MCNQA56GJFXY45mZc47yG5KQ@mail.gmail.com/
[2] https://lore.kernel.org/lkml/20200422144055.18171-1-ggherdovich@suse.cz/
[3] https://lore.kernel.org/lkml/20200424013222.GA26355@ranerica-svr.sc.intel.com/

Giovanni Gherdovich (2):
  x86, sched: Prevent divisions by zero in frequency invariant
    accounting
  x86, sched: Bail out of frequency invariance if turbo frequency is
    unknown

 arch/x86/kernel/smpboot.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

-- 
2.16.4


             reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-28 13:24 Giovanni Gherdovich [this message]
2020-04-28 13:24 ` [PATCH 1/2] x86, sched: Prevent divisions by zero in frequency invariant accounting Giovanni Gherdovich
2020-04-29 11:30   ` Rafael J. Wysocki
2020-05-01 13:30   ` Peter Zijlstra
2020-05-02 14:25     ` Giovanni Gherdovich
2020-05-18 22:20       ` Ricardo Neri
2020-05-19 16:46         ` Giovanni Gherdovich
2020-04-28 13:24 ` [PATCH 2/2] x86, sched: Bail out of frequency invariance if turbo frequency is unknown Giovanni Gherdovich
2020-04-29 11:30   ` Rafael J. Wysocki
2020-05-01 13:04   ` Peter Zijlstra
2020-05-02  0:06     ` Ricardo Neri
2020-05-02 14:26     ` Giovanni Gherdovich
2020-05-02  0:04   ` Ricardo Neri

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