lazy p4?

[billou2k]

Hi I didn't know where to post that so I guess here is the best place:
I ve recently bought a P4 3Ghz hyperthreading system and I'm doing some backups using gknot / vdub / xvid.
I was expecting reasonnable speed but strangely and even though I'm using quality settings in XVID (VQH 4 and Qpel on, yes i've read the gknot encoding faq ;-) ) it's surprisingly slow...
Having a look at the task manager I discovered the processor is only used at 60% (having nothing else than vdubmod running)
I tried forcing real time settings from the task manager and vdub thread priority but no change there

I also have the same behaviour with besweet...

Anybody got an idea what he could be due to?

thanks

[OvERaCiD23]

I don't know if it it still exists, but there is/was a P4 optimized version of VDub/VDubMod. Check if it's still there on the SourceForge site.

[Selur]

since "VQH 4" isn't "da bomb" (speed wise) on a "real" multi proc system, I suspect it also doesn't use hyperthreading,...

Better lower vhq,... (if you want more speed)
I suspect, disabling vhq should result in a 100% CPU usage. ;)

"Anybody got an idea what he could be due to?"
You used methods, task that can't be optimized of smp or hyperthreading.

Cu Selur

[billou2k]

Hi Selur thanks you are right,
I did some more tests with divx3.11 divx5.05
and cpu charge gets close to 100%
the same happens if I set VHQ to 0

I dont mind if the encoding is slower with VHQ 4 as long as its better than VHQ 2 or 3 , I was just finding odd that the cpu charge was not at 100% during an encoding process... :o

So the reason it's around 60-70% is due to the fact that hyperthreading doesnt provide any gain for these algos (VHQ 4)?
So for other apps when the cpu charge is at 100% does it mean that the hyperthreading feature of the P4 manages to perform like 2 processors?

but in this particular case (xvid encoding with vhq 4) the processor is actually used as its maximumn potential right? so I was just expecting the cpu charge showing 100% rather than 60%..
is there a reason why it is not so?

cheers

[Selur]

"So the reason it's around 60-70% is due to the fact that hyperthreading doesnt provide any gain for these algos (VHQ 4)?"
Yup

"So for other apps when the cpu charge is at 100% does it mean that the hyperthreading feature of the P4 manages to perform like 2 processors?" Guess so, I'm not to sure how hyperthreading really functions.

"but in this particular case (xvid encoding with vhq 4) the processor is actually used as its maximumn potential right?"
don't think so, but like I know i'm not to sure how hyperthreading works.

Cu Selur
Ps.: There are probably other people in the forum who can clear this up,.. ;)

[billou2k]

Thanks Selur,

Yes there might be some guys (no girls?;-) ) around who know more about it...
Anyway as long as it doesnt crash or doesnt stop processing I guess it's fine :D
I can live with it (until someone tells me why the cpu charge is just shown at 60-70% ;-) ) but It'd have found it normal if for an encoding procedure the CPU'd dedicate 100% of its "time" on it to finish the whole process as quick as possible.
What would be the interest leaving some resources unused when you have got a two hours sequence to encode?
Well I guess the cpu charge reported is somehow modified to take in account the hyperthreading ...
Well I'd better stop guessing and let speak the people who know ;-)

See you

[killingspree]

as far as the OS is concerned hyperthreading is the same as a multi (dual) processor rig. So the OS 'thinks' that it is dealing with two logical processors.
So if you are using a program/ executing a task that doesn't utilize dual processor systems, the computer will think that you only use one logical processor. therefore it doesn't show the '100%'. in reality it is most likely that your processor is used almost to it's full extend and is running at the same speed as a PIV with 3 GHz, but no HT.

HT is kind of a "cheat" that enables programs to better utilize the resources the processor probvides and in fact can suposedly improve the performance by 30%. this is only the fact in very few, mostly professional applications.

hope this explains it a bit

steVe

[billou2k]

hi killingspree thanks for the explanation
it makes sense but I just think it's not really easy for the 'average' user to find out why it happens;-)
anyway we know for years now that it's up to us to understand technology and not the opposite as it should be;)

thanks for the comments guys!