Re: [PATCH] perfc: Print a system time in a convenient format

From: George Dunlap <george.dunlap@citrix.com>
To: Jan Beulich <JBeulich@suse.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	"andrii_anisov@epam.com" <andrii_anisov@epam.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Tim Deegan <tim@xen.org>, Ian Jackson <Ian.Jackson@eu.citrix.com>,
	andrii.anisov@gmail.com, Julien Grall <julien.grall@arm.com>,
	xen-devel <xen-devel@lists.xenproject.org>,
	Wei Liu <wei.liu2@citrix.com>
Subject: Re: [PATCH] perfc: Print a system time in a convenient format
Date: Tue, 11 Sep 2018 10:28:37 +0100	[thread overview]
Message-ID: <4a4d7ad8-be0d-ee52-5657-fd90eaaab420@citrix.com> (raw)
In-Reply-To: <5B97886002000078001E7151@prv1-mh.provo.novell.com>

On 09/11/2018 10:18 AM, Jan Beulich wrote:
>>>> On 11.09.18 at 11:15, <andrew.cooper3@citrix.com> wrote:
>> On 11/09/18 10:10, Jan Beulich wrote:
>>>>>> On 11.09.18 at 10:50, <andrii_anisov@epam.com> wrote:
>>>> On 11.09.18 11:27, Jan Beulich wrote:
>>>>> NAK, for two reasons: I'm not of the opinion that reading a 15 or more
>>>>> digit decimal number without any separators is any easier than the
>>>>> current format.
>>>> It's quite subjective. IMHO timestamps measured in ns easier to 
>>>> understand in decimals rather than in separated 32-bit hex-es. No matter 
>>>> how many digital number they have.
>>> It is subjective, yes, but in such a case you even more so need to
>>> demonstrate a change is an overall improvement.
>>>
>>>> Even post processing of perfc output is easier in case of decimal 
>>>> timestamps. You should not parse hexes and odd separators to calculate 
>>>> the time elapsed between two samples.
>>> Post processing usually uses scrips for parsing - I don't think it's
>>> overly complicated to have a script convert the number into
>>> basically any format you want.
>>
>> Right, but this particular mis-pattern wants fixing.  It is simply
>> confusing to have a single number formatted with a colon inbetween.
> 
> What other separator do you suggest? I consider it quite helpful
> to have one when there are more than about 10 digits. (I'd also
> be fine, btw, to have the time printed in decimal, but then
> perhaps with ms granularity and 6 digits for the fractional part.)

* We clearly already have a standard way of printing stime
* The places where a colon is used are non-standard, and thus wrong
* His patch makes an improvement by fixing the non-standard timestamp
printing.

If you're not happy with the current PRI_stime, then it should be on you
to propose and code up a change, not Andrii (unless he feels
particularly motivated to do so).

 -George

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