[Eeglablist] Accelerating lowpass running time

[Mikołaj Magnuski]

Dear Avi,

I would suggest using eeglab 12.0.1.(something) or higher
or download eeglab filter plugin by Andreas Widmann.
It is optimized for multi-threading, and does not filter
'backwards' to retain correct phase but instead shifts
the signal by the filter delay - altogether it should be
much faster (in current eeglab versions Andreas' plugin
is the default filter).

Mikołaj

Pozdrawiam,
Mikołaj Magnuski


2013/6/9 Avi Lazarovits <avila at post.bgu.ac.il>

> Hello,
>
> I am using EEGlab to process EEG recordings, and running low pass 100 Hz
> is very slow. I am looking for code modifications I can make to accelerate
> the running time, and also recommendation for optimal hardware specs for
> this process.
>
> The files I process are recordings of 66 channles @ 2KHz ~10 minutes long
> (1086734 samples) bug. I can't resample the files because I need high
> temporal resolution.
>
> I use EEGlab version 11.0.3.1b, and run "firls" filter. I run the filter
> with the following command:
>
> EEG = pop_eegfilt( EEG, 0, 100, [], 0,0, 0, 'firls', 0);
>
> When I run this command I get the following message:
>
> eegfilt() - performing 6144-point highpass filtering.
>
> eegfilt() - highpass transition band width is 0.2 Hz.
>
>
>
> The computer I run the processing on now is i5 3470 (4 cores@ 3.2 Ghz)
> with 4Gb RAM running windows 7 enterprise 64 bit and Matlab 2012a.
>
> I tried running the same process on an i7 extreme edition 3930k with 64Gb
> RAM system and it didn't shorten the running time at all. I also tried
> running this filter on a workstation with Xeon CPU and it shortened the
> running time, but not significantly. I looked on the CPU monitor and found
> that it doesn't use more than 1 core, and that the maximal RAM memory usage
> during the processing was about 6.5 Gb.
>
> 1.     I found that using SSD shortens the time significantly, and
> therefore I assume that one of the big bottlenecks of this processing is
> that the process is made on the hard disk and not on the RAM. Is there a
> way to "make" Matlab use RAM instead of the hard drive?
>
> 2.     Are there code changes I can make in EEGlab's code to run this
> filter multithreaded so that the process will use all the cores of my CPU?
> Is there any way to make this process on GPU? Will it accelerate the
> process more than using parallel computing of the CPU?
>
>
>
> Thank you
>
> Avi
>
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