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From: Jason Andryuk <jandryuk@gmail.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: "Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>,
	"George Dunlap" <george.dunlap@citrix.com>,
	"Ian Jackson" <iwj@xenproject.org>,
	"Julien Grall" <julien@xen.org>,
	"Stefano Stabellini" <sstabellini@kernel.org>,
	xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH 06/13] cpufreq: Export HWP parameters to userspace
Date: Fri, 28 May 2021 09:19:39 -0400	[thread overview]
Message-ID: <CAKf6xptN13CW78XajgyE0G8t2NjFVka8tzNO2oofjcw7tT7n8g@mail.gmail.com> (raw)
In-Reply-To: <e54c3aef-4c44-4302-f7f4-4f4733e33780@suse.com>

On Thu, May 27, 2021 at 4:03 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> On 03.05.2021 21:28, Jason Andryuk wrote:
> > --- a/xen/drivers/acpi/pmstat.c
> > +++ b/xen/drivers/acpi/pmstat.c
> > @@ -290,6 +290,12 @@ static int get_cpufreq_para(struct xen_sysctl_pm_op *op)
> >              &op->u.get_para.u.ondemand.sampling_rate,
> >              &op->u.get_para.u.ondemand.up_threshold);
> >      }
> > +
> > +    if ( !strncasecmp(op->u.get_para.scaling_governor,
> > +                      "hwp-internal", CPUFREQ_NAME_LEN) )
> > +    {
> > +        ret = get_hwp_para(policy, &op->u.get_para.u.hwp_para);
> > +    }
> >      op->u.get_para.turbo_enabled = cpufreq_get_turbo_status(op->cpuid);
>
> Nit: Unnecessary parentheses again, and with the leading blank line
> you also want a trailing one. (As an aside I'm also not overly happy
> to see the call keyed to the governor name. Is there really no other
> indication that hwp is in use?)

This is preceded by similar checks for "userspace" and "ondemand", so
it is following existing code.  Unlike other governors, hwp-internal
is static.  It could be exported if you want to switch to comparing
with cpufreq_driver.

> > --- a/xen/include/acpi/cpufreq/cpufreq.h
> > +++ b/xen/include/acpi/cpufreq/cpufreq.h
> > @@ -246,4 +246,7 @@ int write_userspace_scaling_setspeed(unsigned int cpu, unsigned int freq);
> >  void cpufreq_dbs_timer_suspend(void);
> >  void cpufreq_dbs_timer_resume(void);
> >
> > +/********************** hwp hypercall helper *************************/
> > +int get_hwp_para(struct cpufreq_policy *policy, struct xen_hwp_para *hwp_para);
>
> While I can see that the excessive number of stars matches what
> we have elsewhere in the header, I still wonder if you need to go
> this far for a single declaration. If you want to stick to this,
> then to match the rest of the file you want to follow the comment
> by a blank line.

Will remove.

> > --- a/xen/include/public/sysctl.h
> > +++ b/xen/include/public/sysctl.h
> > @@ -301,6 +301,23 @@ struct xen_ondemand {
> >      uint32_t up_threshold;
> >  };
> >
> > +struct xen_hwp_para {
> > +    uint16_t activity_window; /* 7bit mantissa and 3bit exponent */
>
> If you go this far with commenting, you should also make the further
> aspects clear: Which bits these are, and that the exponent is taking
> 10 as the base (in most other cases one would expect 2).

Yes, this is much more useful.

> > +#define XEN_SYSCTL_HWP_FEAT_ENERGY_PERF (1 << 0) /* energy_perf range 0-255 if
> > +                                                    1. Otherwise 0-15 */
> > +#define XEN_SYSCTL_HWP_FEAT_ACT_WINDOW  (1 << 1) /* activity_window supported
> > +                                                    if 1 */
>
> Style: Comment formatting. You may want to move the comment on separate
> lines ahead of what they comment.
>
> > +    uint8_t hw_feature; /* bit flags for features */
> > +    uint8_t hw_lowest;
> > +    uint8_t hw_most_efficient;
> > +    uint8_t hw_guaranteed;
> > +    uint8_t hw_highest;
>
> Any particular reason for the recurring hw_ prefixes?

The idea was to differentiate values provided by CPU hardware from
user-configured values.

Regards,
Jason


  reply	other threads:[~2021-05-28 13:20 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-03 19:27 [PATCH 00/13] Intel Hardware P-States (HWP) support Jason Andryuk
2021-05-03 19:27 ` [PATCH 01/13] cpufreq: Allow restricting to internal governors only Jason Andryuk
2021-05-26 13:18   ` Jan Beulich
2021-05-26 14:12     ` Jason Andryuk
2021-05-26 15:09       ` Jan Beulich
2021-05-26 16:44         ` Jason Andryuk
2021-05-03 19:27 ` [PATCH 02/13] cpufreq: Add perf_freq to cpuinfo Jason Andryuk
2021-05-26 13:24   ` Jan Beulich
2021-05-26 14:19     ` Jason Andryuk
2021-05-03 19:28 ` [PATCH 03/13] cpufreq: Export intel_feature_detect Jason Andryuk
2021-05-26 13:27   ` Jan Beulich
2021-05-26 14:44     ` Jason Andryuk
2021-05-26 15:11       ` Jan Beulich
2021-05-03 19:28 ` [PATCH 04/13] cpufreq: Add Hardware P-State (HWP) driver Jason Andryuk
2021-05-26 14:59   ` Jan Beulich
2021-05-27  7:23     ` Jan Beulich
2021-05-27 18:50     ` Jason Andryuk
2021-05-28  6:35       ` Jan Beulich
2021-06-03 11:55         ` Jason Andryuk
2021-06-04  6:39           ` Jan Beulich
2021-05-27  7:45   ` Jan Beulich
2021-05-03 19:28 ` [PATCH 05/13] xenpm: Change get-cpufreq-para output for internal Jason Andryuk
2021-05-26 15:21   ` Jan Beulich
2021-05-27  5:54     ` Jan Beulich
2021-05-03 19:28 ` [PATCH 06/13] cpufreq: Export HWP parameters to userspace Jason Andryuk
2021-05-27  7:55   ` Jan Beulich
2021-05-28 13:19     ` Jason Andryuk [this message]
2021-05-28 13:39       ` Jan Beulich
2021-05-03 19:28 ` [PATCH 07/13] libxc: Include hwp_para in definitions Jason Andryuk
2021-05-03 19:28 ` [PATCH 08/13] xenpm: Print HWP parameters Jason Andryuk
2021-05-27  8:02   ` Jan Beulich
2021-05-03 19:28 ` [PATCH 09/13] xen: Add SET_CPUFREQ_HWP xen_sysctl_pm_op Jason Andryuk
2021-05-27  8:33   ` Jan Beulich
2021-05-03 19:28 ` [PATCH 10/13] libxc: Add xc_set_cpufreq_hwp Jason Andryuk
2021-05-04  8:03   ` Jan Beulich
2021-05-04 11:31     ` Jason Andryuk
2021-05-27  9:45   ` Jan Beulich
2021-05-03 19:28 ` [PATCH 11/13] xenpm: Factor out a non-fatal cpuid_parse variant Jason Andryuk
2021-05-27  8:41   ` Jan Beulich
2021-05-03 19:28 ` [PATCH 12/13] xenpm: Add set-cpufreq-hwp subcommand Jason Andryuk
2021-05-27  9:46   ` Jan Beulich
2021-05-03 19:28 ` [PATCH 13/13] CHANGELOG: Add Intel HWP entry Jason Andryuk
2021-05-27  9:48   ` Jan Beulich
2021-05-20 14:57 ` [PATCH 00/13] Intel Hardware P-States (HWP) support Jan Beulich

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