From: Glauber Costa <glommer@parallels.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <linux-kernel@vger.kernel.org>, <xemul@parallels.com>,
<paul@paulmenage.org>, <lizf@cn.fujitsu.com>,
<daniel.lezcano@free.fr>, <mingo@elte.hu>,
<jbottomley@parallels.com>
Subject: Re: [PATCH 8/9] per-cgroup boot time
Date: Tue, 20 Sep 2011 10:06:25 -0300 [thread overview]
Message-ID: <4E788FD1.40301@parallels.com> (raw)
In-Reply-To: <1316523860.13664.11.camel@twins>
On 09/20/2011 10:04 AM, Peter Zijlstra wrote:
> On Tue, 2011-09-20 at 09:37 -0300, Glauber Costa wrote:
>
>>>> + getboottime(&boottime);
>>>> + ts = timespec_add(boottime, ca->start_time);
>>>> + jif = ts.tv_sec;
>>>>
>>>> for_each_possible_cpu(i) {
>>>> cpustat = per_cpu_ptr(ca->cpustat, i);
>>>
>>>
>>> I'm confused, what does it do? You take a boot time timestamp at cgroup
>>> creation, add that to all boot-time readings and print the result. How
>>> does that make sense? Subtracting the start_time, maybe, that would make
>>> the cgroup creation time 0, adding, not so much.
>>
>> Boot time represent at which times the machine was booted. In this
>> context, at which time the container/cgroup was created. So it have to
>> be an addition.... don't really understand your question
>
> I think we're all properly confused now :-)
>
> getboottime() gives a time since boot, right?
>
> You take stamp at cgroup creation: say 50s after boot.
>
> Then on usage you take a new getboottime() reading (which per definition
> is> 50s) and add your 50s that you read previous. This results in the
> cgroup having 50s of boot-time _MORE_ than the machine. Say you read at
> 123s, you then add your 50s timestamp, resulting in 173s to report.
>
> If instead you did a subtraction: 123-50=73, you would have reported the
> time since cgroup creation.
>
no.
/**
* getboottime - Return the real time of system boot.
* @ts: pointer to the timespec to be set
*
* Returns the wall-time of boot in a timespec.
...
next prev parent reply other threads:[~2011-09-20 13:07 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-14 20:04 [PATCH 0/9] Per-cgroup /proc/stat Glauber Costa
2011-09-14 20:04 ` [PATCH 1/9] Remove parent field in cpuacct cgroup Glauber Costa
2011-09-19 16:03 ` Peter Zijlstra
2011-09-19 16:09 ` Glauber Costa
2011-09-19 16:19 ` Peter Zijlstra
2011-09-19 16:30 ` Glauber Costa
2011-09-19 16:39 ` Peter Zijlstra
2011-09-19 16:41 ` Glauber Costa
2011-09-19 18:40 ` Peter Zijlstra
2011-09-20 17:29 ` Srivatsa Vaddagiri
2011-09-22 15:11 ` Balbir Singh
2011-09-22 15:17 ` Peter Zijlstra
2011-09-23 8:09 ` Balbir Singh
2011-09-23 14:35 ` Peter Zijlstra
2011-09-23 15:45 ` Glauber Costa
2011-09-19 18:35 ` Peter Zijlstra
2011-09-19 18:38 ` Glauber Costa
2011-09-19 18:44 ` Peter Zijlstra
2011-09-19 19:14 ` Glauber Costa
2011-09-19 19:18 ` Peter Zijlstra
2011-09-19 19:19 ` Glauber Costa
2011-09-14 20:04 ` [PATCH 2/9] Make cpuacct fields per cpu variables Glauber Costa
2011-09-19 16:10 ` Peter Zijlstra
2011-09-14 20:04 ` [PATCH 3/9] Include nice values in cpuacct Glauber Costa
2011-09-19 16:19 ` Peter Zijlstra
2011-09-19 16:26 ` Glauber Costa
2011-09-19 18:36 ` Peter Zijlstra
2011-09-19 18:37 ` Glauber Costa
2011-09-14 20:04 ` [PATCH 4/9] Include irq and softirq fields " Glauber Costa
2011-09-19 18:38 ` Peter Zijlstra
2011-09-19 18:40 ` Glauber Costa
2011-09-14 20:04 ` [PATCH 5/9] Include guest " Glauber Costa
2011-09-14 20:04 ` [PATCH 6/9] Include idle and iowait " Glauber Costa
2011-09-20 9:21 ` Peter Zijlstra
2011-09-20 12:36 ` Glauber Costa
2011-09-20 12:58 ` Peter Zijlstra
2011-09-20 12:58 ` Glauber Costa
2011-09-20 13:05 ` Peter Zijlstra
2011-09-20 13:29 ` Glauber Costa
2011-09-14 20:04 ` [PATCH 7/9] Create cpuacct.proc.stat file Glauber Costa
2011-09-20 9:22 ` Peter Zijlstra
2011-09-20 12:22 ` Glauber Costa
2011-09-14 20:04 ` [PATCH 8/9] per-cgroup boot time Glauber Costa
2011-09-20 9:25 ` Peter Zijlstra
2011-09-20 12:37 ` Glauber Costa
2011-09-20 13:04 ` Peter Zijlstra
2011-09-20 13:06 ` Glauber Costa [this message]
2011-09-20 13:31 ` Peter Zijlstra
2011-09-14 20:04 ` [PATCH 9/9] Report steal time for cgroup Glauber Costa
2011-09-20 9:29 ` Peter Zijlstra
2011-09-14 20:13 ` [PATCH 0/9] Per-cgroup /proc/stat Peter Zijlstra
2011-09-14 20:20 ` Glauber Costa
2011-09-15 8:53 ` Peter Zijlstra
2011-09-14 20:23 ` Andi Kleen
2011-09-15 8:56 ` Peter Zijlstra
2011-09-19 23:07 ` Paul Turner
2011-09-20 8:33 ` Peter Zijlstra
2011-09-20 21:37 ` Glauber Costa
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