[THIN] Re: latency

  • From: "Braebaum, Neil" <neil.braebaum@xxxxxxxxxxxxxxxxxxxxxxxx>
  • To: "'thin@xxxxxxxxxxxxx'" <thin@xxxxxxxxxxxxx>
  • Date: Fri, 4 Oct 2002 09:36:43 +0100


Just to clarify - are you suggesting there are circumstances where counters
are not reporting, or not accounting for system / kernel activity (ie that
it is being underreported)?

Or merely that this information is somewhat obfuscated?

I find it difficult to believe that system / kernel activity is effectively
black-holing from a reporting / monitoring perspective - be it from task
manager, or perfmon.

I'd agree that system / kernel activity can be difficult to track down
exactly as to the cause, but I've *never* encountered scenarios where the
system has busy cpus, but misleading counters - except for when a machine is
so obviously *so* busy, that the monitoring application / utility isn't
getting a look in.


> -----Original Message-----
> From: Bernd Harzog [mailto:bernd@xxxxxxxxxxx] 
> Sent: 03 October 2002 22:32
> To: thin@xxxxxxxxxxxxx
> Subject: [THIN] Re: latency
> The behavior that Eric describes is very interesting. The 
> important point is a drop in CPU utilization when the latency 
> occurs. What this means is two things; 1) The CPU utilization 
> counter is not measuring whatever is causing the latency, 2) 
> Something is causing the CPU to spend a lot of time doing 
> something instead of useful work on behalf of user applications.
> There is a scenario which we have encountered at customers 
> which fits into the above explanation. That scenario is that 
> the time that the CPU spends on certain system level 
> operations (kernel mode operations like Page File Writes, and 
> Page Faults) is not counted by the CPU utilization counter, 
> AND that something is making the CPU spend a lot of time 
> these Kernel Mode operations. The things that can cause these 
> kinds of Kernel Mode operations to block useful work include 
> a saturated disk driver, a large number of queued up page 
> writes, a large number of page faults and numerous other things.
> If you are experiencing this kind of behavior, and it is 
> being caused by excessive paging (watch page file writes in 
> Perfmon), then TSCale will help. If you are saturating your 
> RAID drivers TScale cannot help.

This e-mail and its attachments are intended for the above named 
recipient(s) only and are confidential and may be privileged.
If they have come to you in error you must take no action based 
on them, nor must you copy or disclose them or any part of 
their contents to any person or organisation; please notify the 
sender immediately and delete this e-mail and its attachments from 
your computer system.

Please note that Internet communications are not necessarily secure 
and may be changed, intercepted or corrupted. We advise that 
you understand and observe this lack of security when e-mailing us 
and we will not accept any liability for any such changes, 
interceptions or corruptions. 

Although we have taken steps to ensure that this e-mail and its 
attachments are free from any virus, we advise that in keeping 
with good computing practice the recipient should ensure they 
are actually virus free.

Copyright in this e-mail and attachments created by us belongs 
to Littlewoods. 

Littlewoods takes steps to prohibit the transmission of offensive, 
obscene or discriminatory material.  If this message contains 
inappropriate material please forward the e-mail intact to 
postmaster@xxxxxxxxxxxxxxxxx and it will be investigated. 
Statements and opinions contained in this e-mail may not 
necessarily represent those of Littlewoods.

Please note that e-mail communication may be monitored.

Registered office: 
Littlewoods Retail Limited, 
Sir John Moores Building, 
100 Old Hall Street, 
L70 1AB 
Registered no: 421258 

This weeks sponsor 99Point9.com
99Point9 helps solve your unresolved technical
server-based questions, issues and incidents.

For Archives, to Unsubscribe, Subscribe or 
set Digest or Vacation mode use the below link.


Other related posts: