lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Sun, 17 Feb 2019 11:25:37 -0800
From:   "Doug Smythies" <>
To:     "'Rafael J. Wysocki'" <>,
        "'Linux PM'" <>
Cc:     "'Srinivas Pandruvada'" <>,
        "'LKML'" <>,
        "Doug Smythies" <>
Subject: RE: [PATCH v2] cpufreq: intel_pstate: Rework iowait boosting to be less aggressive

On 2019.02.07 03:51 Rafael J. Wysocki wrote:

> From: Rafael J. Wysocki <>
> The current iowait boosting mechanism in intel_pstate_update_util()
> is quite aggressive, as it goes to the maximum P-state right away,
> and may cause excessive amounts of energy to be used, which is not
> desirable and arguably isn't necessary too.
> Follow commit a5a0809bc58e ("cpufreq: schedutil: Make iowait boost
> more energy efficient") that reworked the analogous iowait boost
> mechanism in the schedutil governor and make the iowait boosting
> in intel_pstate_update_util() work along the same lines.
> Signed-off-by: Rafael J. Wysocki <>
> ---
> -> v2:
>   * Follow the Doug's suggestion and drop the immediate jump to
>     max P-state if boost is max.  The code is simpler this way and
>     the perf impact should not be noticeable on average.

Hi Rafael,

Something has broken on my incoming e-mail sorting stuff, and I
missed this one (and some others).

This V2 is not actually what I was proposing. I was O.K. with
the immediate jump, but I didn't want the set_pstate step
by-passed if it was already at max because that would also
by-pass the trace sample, if it was enabled.

Anyway, this V2 seems O.K. to me. I tested it compared to V1
and, as you mentioned, wasn't able to detect any energy consumption
or performance differences.

... Doug

Powered by blists - more mailing lists