atop

Kapil Thangavelu kapil.thangavelu at canonical.com
Tue Aug 17 01:38:12 UTC 2010


On Tue, 13 Jul 2010 23:15:00 -0400, Cole <coleton at gmail.com> wrote:

> So this may be a little long winded...
>
> To quickly preface my thoughts I first want to state something pretty
> obvious.  In a multi tenant environment ( the current direction we seem  
> to
> be headed ) I could care less about some of the tools that are packaged  
> in
> sysstat and procps.  I don't care about load avg etc for self explanatory
> reasons and presently io reporting (especially in a multi app/multi user
> scenario) is lacking.
>
> That being said I think tools like atop, systemtap, oprofile are good but
> present 2 problems.  They are still tools with competition from closed
> source companies ( BMC to name 1) that will ultimately lead to  
> discrepancies
> in collected data and they stop short of the challenge The Linux  
> Foundation
> has asked the community to tackle with regard to keeping the kernel  
> relevant
> for the next 5-10 years.
>
> KSLM is focused purely on gathering statistics around the 5 basic  
> principals
> of compute ( cpu / memory / disk (storage) / time / IO (disk and net) on  
> a
> per process basis in a standard way across distros and cpu architectures
> using a consistent thing across all implementations (the kernel itself).
>
> So to summarize, could kslm be used to solve the same issue described  
> below,
> yep!  Would it be as elegant as atop?  Part of it's elegance is that it's
> distro agnostic and if used correctly, could be used to actually do
> intelligent workload management and remediation if conditions (like long
> disk waits) are met.
>
> Cole
>

One issue, is that it appears that is zero public information (as per  
google) on KSLM. Could you lend any pointers to code or documentation  
about KSLM? I waited and had a look at your linuxcon slides but there's  
not much content there.
http://events.linuxfoundation.org/slides/2010/linuxcon2010_crawford.pdf

All measurement tools will face competition from other measurement tools,  
be they commercial or opensource. In terms of distro agnostic mechanisms  
of capturing those 5 metrics on a per process basis, afaics atop w/ kernel  
process accounting patch does indeed provide this minus the notion of  
process disk (storage).

thanks,

Kapil


>
> On Tue, Jul 13, 2010 at 2:04 PM, Clint Byrum  
> <clint.byrum at canonical.com>wrote:
>
>>
>> On Jun 30, 2010, at 1:10 PM, Tim Gardner wrote:
>> >
>> > You are correct in that I am reluctant to drag in unmaintained crack
>> > into core kernel structures.
>> >
>> > I still find 'better task accounting' to be insufficient  
>> justification.
>> > What specifically makes for better task accounting? Why is atop better
>> > then other methods? As far as I can tell the current patches still
>> > suffer from the deficiencies mentioned by Andrew Morton in
>> > http://marc.info/?l=linux-kernel&m=120716470803492&w=2
>> >
>> > Gimme an example of a problem that atop will help solve for which no
>> > other method will suffice.
>> >
>>
>> I just recently was contacted by a friend looking for help on periodic
>> "total site freeze" issues with a web application. Atop revealed some  
>> badly
>> behaving processes where regular top did not, because processes "in disk
>> wait" might be waiting to read/write, and with hundreds of httpd's on  
>> the
>> machine in disk wait, its painful to try and find out whats going on.  
>> Its
>> such an instant revelation of activity, I really think as systems scale  
>> up
>> these sorts of tools are really vital.
>>
>> Whether atop as it is now is the way to do this remains to be decided. I
>> recall talking with Cole Crawford at UDS about KSLM which may add  
>> similar
>> capabilities to the kernel but in a more elegant way. I've CC'd Cole to  
>> get
>> his opinion on this as well.
>>




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