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This module analyzes the effectiveness of reording data structures in a filter bank implementation to achieve higher efficiency.

This module is a continuation of the previous module on POSIX thread implementations.

Implementation 3: partial reordering

An area for improvement over the previous p-thread implementations is to reorder some of the arrays that the filter uses to store data. We started by restructuring the output vector. We split the output vector into a two-dimensional array giving each thread its own output vector. This separates each thread's data in memory, cutting down on cache poisonings. Note that this does change the structure of the final output, but this change is acceptable given that the Open Ephys GUI can be threaded to read in the filter output from several vectors at once.

We ran the same sequence of tests as before using this modified implementations and observed the following results:

Number of Threads Runtime (s)
Control (main thread) 50.106
1 49.302
2 78.888
4 89.939
8 35.283
16 71.337
32 109.112

Implementation 4: full reordering

Another area for significant improvement was to restructure the intermediate data vectors. The vectors were originally designed to store the intermediate filter values of w1, w2, w3 and w4 (see module on Transposed Direct-Form II implementation) in separate arrays. All the threads also shared the arrays, but wrote to different values within the array.

We constructed an alternate structure where all the intermediate filter values of each channel were located in adjacent memory values in a single large vector. Each thread would have its own intermediate value vector for the channels that it was processing. What this does is enable spatial locality for the intermediate values for each channel, which tend to be used all at the same time (temporal locality). The locality of this data ensure that cache hits occur frequently. Splitting the intermediate value vector by thread will help limit cache poisoning.

Using the same sequence of tests to benchmark this implementation, we observed the following results:

Number of Threads Runtime (s)
Control (main thread) 71.166
1 57.156
2 52.639
4 48.939
8 33.589
16 51.543
32 110.716

Analysis of results

A dog sitting on a bed

The obtained results show a very promising improvement, especially after implementing a full reordering scheme. With data reordering, the cache effects of the previous POSIX implementations are significantly reduced. We cannot circumvent p-thread overhead, which indicates why a higher number of p-threads still continues to perform poorly, regardless of data reordering.

With clever data reordering, p-thread implementations of the filter bank can provide significant speed gains over comparable single-threaded methods. The fastest run time obtained by these implementations ran in under 34 seconds with full reordering. This is much faster than the 48 second run time posted by the fastest single-threaded implementation.

Questions & Answers

what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Efficient real-time filter design for recording multichannel neural activity. OpenStax CNX. Dec 11, 2012 Download for free at http://cnx.org/content/col11461/1.1
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