linux-kernel - RE: [PATCH v2] cpuidle: poll_state: Add time limit to poll

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Message-ID: <003f01d3c211$9a094e10$ce1bea30$@net>
Date:   Thu, 22 Mar 2018 12:11:33 -0700
From:   "Doug Smythies" <dsmythies@...us.net>
To:     "'Rik van Riel'" <riel@...riel.com>
Cc:     "'Linux PM'" <linux-pm@...r.kernel.org>,
        "'Frederic Weisbecker'" <fweisbec@...il.com>,
        "'Thomas Gleixner'" <tglx@...utronix.de>,
        "'Paul McKenney'" <paulmck@...ux.vnet.ibm.com>,
        "'Thomas Ilsche'" <thomas.ilsche@...dresden.de>,
        "'Aubrey Li'" <aubrey.li@...ux.intel.com>,
        "'Mike Galbraith'" <mgalbraith@...e.de>,
        "'LKML'" <linux-kernel@...r.kernel.org>,
        "'Peter Zijlstra'" <peterz@...radead.org>,
        "'Rafael J. Wysocki'" <rjw@...ysocki.net>,
        "Doug Smythies" <dsmythies@...us.net>
Subject: RE: [PATCH v2] cpuidle: poll_state: Add time limit to poll_idle()

On 2018.03.22 09:32 Rik van Riel wrote:
> On Wed, 2018-03-14 at 13:04 +0100, Peter Zijlstra wrote:
>
>> On x86 we don't have to use that time_check_counter thing,
>> sched_clock()
>> is really cheap, not sure if it makes sense on other platforms.
>
> Are you sure? I saw a 5-10% increase in CPU use,
> for a constant query rate to a memcache style
> workload, with v3 of this patch.

I would very much like to be able to repeat your test results.
However, I am not sure what you mean by "memcache style workload".
Is there a test you can point me to? Say a Phoronix type test, for example.

All of my tests with the V3 of this patch have been fine.

... Doug