linux-kernel - RE: [PATCH v2 3/3] clocksource: Add clockevent support to NPS400 driver

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Message-ID: <DB6PR0501MB2518E3DB42944573E0AF0B04AAB80@DB6PR0501MB2518.eurprd05.prod.outlook.com>
Date:   Thu, 10 Nov 2016 13:00:57 +0000
From:   Noam Camus <noamca@...lanox.com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
CC:     "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Vineet Gupta <Vineet.Gupta1@...opsys.com>
Subject: RE: [PATCH v2 3/3] clocksource: Add clockevent support to NPS400
 driver

>From: Daniel Lezcano [mailto:daniel.lezcano@...aro.org] 
>Sent: Thursday, November 10, 2016 12:34 PM

>>> give a correct result without a dmesg log ?
>> [root@....168.8.2 /]$ [root@....168.8.2 /]$ taskset 65536 time sleep 2 
>> & taskset 131072 time sleep 3

>Thanks for providing the numbers.

>So there is no weird messages in dmesg ?
Yes, no weird messages, all seem normal.

>> real    0m 2.54s
>> user    0m 0.04s
>> sys     0m 0.14s
>> real    0m 3.47s
>> user    0m 0.00s
>> sys     0m 0.15s
>> [1]+  Done                       taskset 65536 time sleep 2
>> 
>> Seem OK to me.

>I'm not sure of that.

>2.54 instead of 2
>3.47 instead of 3

>0.02 time drift could be acceptable but 0.54 or 0.47 is too much.

>And 0.15 in sys also a big number AFAICT.

>Is the system in NO_HZ ?

We are handling system with NOHZ_FULL 
This was run under simulation and result are reasonable (indeed not perfect) AFAICT.

-Noam