Author Topic: CPU usage of generic serial device  (Read 369 times)

b4rney

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CPU usage of generic serial device
« on: October 29, 2011, 02:11:18 pm »
Hi Guys,

I've been trying to diagnose why my video media keeps freezing for a couple of seconds then quickly catching up again on my MD. This happens at regular 1-2 minute intervals.

I noticed on all my MDs that when I run 'top' I see 'Generic_Serial_' at the top of the list using 14% cpu. If I have more than one attached AV device then there are two of these (so 28% cpu). My devices are an LG TV and a Denon amp.

Question is ... Is This Normal? That is a lot of CPU for something that is not in use 99.99% of the time. It is more CPU than xine player when watching videos.

I'm running 0810 updated within the last two weeks. VDPAU enabled on my acer revo md (the one that skips).

Barney

posde

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Re: CPU usage of generic serial device
« Reply #1 on: October 29, 2011, 04:35:00 pm »
That's normal, and does not interfere with watching video on my system. I have a Denon amp and a JVC projector connected to a ION based system, and do not see any glitches. I do see the high CPU load which is typical for those RS-232 connections.

tschak909

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Re: CPU usage of generic serial device
« Reply #2 on: October 29, 2011, 08:41:02 pm »
Don't worry about it. Why?

It has to do with the sleep() during the process idle thread in GSD. This is normal, and only marks the GSD process as mostly waiting, which of course, results in a higher load average. It does not affect the CPU usage, as no CPU usage is used during a sleep() except to count how long to sleep. This is a simple set of x86 instructions that take at most 8 CPU cycles each iteration, and seeing that a GHz CPU executes cycles in the billions per second, it's a bit like trying to track down a gnat flying through an airport. Wasteful, and ultimately doesn't mean anything.

-Thom

b4rney

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Re: CPU usage of generic serial device
« Reply #3 on: October 29, 2011, 11:50:57 pm »
Thanks guys.

I will leave the gnat in search of bigger prey!

Maybe just rebuilding the md in question will squash the glitches.

Cheers
Barney