Solved: how to use CPU Throttle ? - Qlik Community

mohamed_ahid · ‎2015-03-09

Hi every body ,

on my server i have several warnings about over use of CPU (99%) .

i try to limite the % of cpu used on server to avoid these kind of message .In performance we have CPU Throttle and CPU Affinity .

what is the aim and the difference of using each other ?

how to use CPU Throttle ti limite the use of CPU to 90 % (0% means no throttling . 100% is throttling ?)

thx

Peter_Cammaert · ‎2015-03-10

Just the same thing. Not having a Publisher license only means that you don't have a "Management Department" for reload tasks. The main impact of not having a license is in the trigger & distribution feature list, not in the actual reload system. The same QVB process will be started, and it will obtain the QDS configuration which says that some cpu cores can be used for reloads and others should be left alone.

Works like a charm.

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mohamed_ahid · ‎2015-03-10

Someone ?!

Peter_Cammaert · ‎2015-03-10

The big question here is: what services are running on the machine with cpu starvation?

The two settings you mentioned apply to the QVS process only. CPU Affinity assigns cores to the QVS process. Every disabled checkbox means that this CPU core wil not be used by the QVS process. The CPU Throttling-setting is a bit wacky. Setting a percentage level will impose a best effort limit to what QVS will do with the remainder of the CPU cores . Except if you set the Throttling level to 0% meaning that the QVS process doesn't do any throttling at all.

Back to my opening: QDS & QVB do not obey any of these nice limitations. You can disable CPU cores for QVB reloads, But just like there is no restraint on the memory usage of a reload, a QVB process will use one or more cores to the max if it feels like it.

And then there still is Windows...

What applications/services is your server hosting?

Peter

mohamed_ahid · ‎2015-03-10

Thx.

my server is hosting only QV server .For RAM there is no probleme (16 go is enough) but with my 8 cores it's another story ,I get 99% used on it while loading .

so if i want to limit the use of cpu to 90% i have to use CPU affinity or CPU throttle?

Peter_Cammaert · ‎2015-03-10

Even if you use CPU Throttling (say at 90%), that setting will apply only to the QVS service. Every time a reload job starts, your server will again experience cpu starvation and your end-users will get awful response times.

To alleviate the load imposed by both QVS and QDS, there are four solutions:

Schedule reloads when few or no AP visitors are using the system (at night)
Divide the cpu cores between users (QVS) and reload jobs (QDS) e.g. 6 for the AccessPoint and 2 for reloads. This isn't ideal as those two cores may remain unused for 90% of the time.
Install additional cpu's (e.g. cores x 2)
Move your QDS set-up to a separate disk IO-optimized platform. This is the only decent long-term solution. However you'll need a Publisher license for that...

Peter

mohamed_ahid · ‎2015-03-10

and how can i Divide the cpu cores between users (QVS) and reload jobs (QDS) ?

Peter_Cammaert · ‎2015-03-10

Use the CPU Affinity setting.

IMHO this is not the best solution because you'll split cpu resources into isolated pools.

mohamed_ahid · ‎2015-03-10

thanx Peter for answers .But i didn't get the aim behind every setting .

CPU affinity limits the nomber of cores used by QV server and throottling is the % of used CPU .

but all of these options have no link with the reload task . am I right ?

Peter_Cammaert · ‎2015-03-10

Yes, you're right.

And this conflict of interests is the main reason why a Publisher is often migrated to a separate machine.

mohamed_ahid · ‎2015-03-10

OK so in my case i have no settings to perform on QMC ,but maybe improve the reload task plan .