[64studio-devel] [Jackit-devel] CPU load reading too high on dual-core and SMP machines?

[Quentin Harley]

OK, why is the clock source important for the calculation of the DSP load on
a dual core machine?  Jack is running, and smoothly.  It's just not running
half as hard as it could on my PC!

Don't get me wrong. I love jack, and it changed the way I work with audio on
PC forever. I just want jack to love me in return...

I know dual cores changes everything, but it is the only way the chip
manufacturers can squeeze more power out of the silicon, and we'll see more
elaborate stuff soon (read: AMD quad core).  Will jackd then report 4x the
CPU load for a 4core chip?  This is a very important fix that needs to be
implemented if jackd has a place in modern PC use.

Thanks to all the dedicated programmers and testers that made jackd what it
is today.

Quentin

-----Original Message-----
From: jackit-devel-bounces at lists.sourceforge.net
[mailto:jackit-devel-bounces at lists.sourceforge.net] On Behalf Of Jussi Laako
Sent: 08 November 2006 00:02
To: Lee Revell
Cc: jackit-devel at lists.sourceforge.net; 64Studio mailing list;
paul at linuxaudiosystems.com
Subject: Re: [Jackit-devel] CPU load reading too high on dual-core and SMP
machines?

Lee Revell wrote:
> Sorry, you're right - I tend to think of them as interchangeable because
> both use sys_gettimeofday() syscall.

No, it should use sys_clock_gettime() syscall which is implemented in
kernel/posix-timers.c. If it doesn't, it's a bug in glibc. And at quick
glance it seems to do the right thing (glibc 2.4 && 2.5).

And a slight clarification; gettimeofday() of course itself functions as
it should, but because of this it's slightly unsuitable for our use (NTP
can adjust it). This is why we use monotonic clock provided by the system.

>> However, the selectable clock source in jack has three options (on x86),
>> 'cycle', 'hpet' and 'system'. And in this case the correct answer would
>> be 'system', ie. "--clocksource s" parameter for the jackd.
> 
> What is the default?

System clock, so nothing needs to be specified to get the correct
behaviour in any case.


	- Jussi

-------------------------------------------------------------------------
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job
easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
_______________________________________________
Jackit-devel mailing list
Jackit-devel at lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/jackit-devel