From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Giovanni Gherdovich <ggherdovich@suse.cz>
Cc: 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>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
"the arch/x86 maintainers" <x86@kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Subject: Re: [PATCH v2 3/3] x86, sched: Bail out of frequency invariance if turbo_freq/base_freq gives 0
Date: Wed, 3 Jun 2020 16:51:21 +0200 [thread overview]
Message-ID: <CAJZ5v0iNFDjt6rqXfiwn_UwiKgJDgAUshChVh5YoOCXF9hy=_A@mail.gmail.com> (raw)
In-Reply-To: <20200531182453.15254-4-ggherdovich@suse.cz>
On Sun, May 31, 2020 at 8:26 PM Giovanni Gherdovich <ggherdovich@suse.cz> wrote:
>
> Be defensive against the case where the processor reports a base_freq
> larger than turbo_freq (the ratio would be zero).
>
> Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance")
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
> arch/x86/kernel/smpboot.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index fe154c8226ba..f619007f46cf 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -1976,6 +1976,7 @@ static bool core_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq)
> static bool intel_set_max_freq_ratio(void)
> {
> u64 base_freq, turbo_freq;
> + u64 turbo_ratio;
>
> if (slv_set_max_freq_ratio(&base_freq, &turbo_freq))
> goto out;
> @@ -2009,9 +2010,15 @@ static bool intel_set_max_freq_ratio(void)
> return false;
> }
>
> - arch_turbo_freq_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE,
> - base_freq);
> + turbo_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE, base_freq);
> + if (!turbo_ratio) {
> + pr_debug("Non-zero turbo and base frequencies led to a 0 ratio.\n");
> + return false;
> + }
> +
> + arch_turbo_freq_ratio = turbo_ratio;
> arch_set_max_freq_ratio(turbo_disabled());
> +
> return true;
> }
>
> --
> 2.16.4
>
next prev parent reply other threads:[~2020-06-03 14:51 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-31 18:24 [PATCH v2 0/3] More frequency invariance fixes for x86 Giovanni Gherdovich
2020-05-31 18:24 ` [PATCH v2 1/3] x86, sched: check for counters overflow in frequency invariant accounting Giovanni Gherdovich
2020-06-03 14:22 ` Rafael J. Wysocki
2020-06-16 12:21 ` [tip: sched/core] " tip-bot2 for Giovanni Gherdovich
2020-10-22 8:46 ` [PATCH v2 1/3] " Peter Zijlstra
2020-10-22 12:21 ` Giovanni Gherdovich
2020-10-22 12:30 ` Peter Zijlstra
2020-05-31 18:24 ` [PATCH v2 2/3] x86, sched: Bail out of frequency invariance if turbo frequency is unknown Giovanni Gherdovich
2020-06-01 23:34 ` Ricardo Neri
2020-07-06 20:19 ` Ira Weiny
2020-06-03 14:23 ` Rafael J. Wysocki
2020-06-16 12:21 ` [tip: sched/core] " tip-bot2 for Giovanni Gherdovich
2020-05-31 18:24 ` [PATCH v2 3/3] x86, sched: Bail out of frequency invariance if turbo_freq/base_freq gives 0 Giovanni Gherdovich
2020-06-03 14:51 ` Rafael J. Wysocki [this message]
2020-06-16 12:21 ` [tip: sched/core] " tip-bot2 for Giovanni Gherdovich
2020-06-03 12:31 ` [PATCH v2 0/3] More frequency invariance fixes for x86 Peter Zijlstra
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