suite

[prng_gpu.git] / prng_gpu.tex

diff --git a/prng_gpu.tex b/prng_gpu.tex
index 19adf220330a1488041bf7d8286444738d40e069..c48aeda1cc9aa4636e434c7410060fbc3c39f26b 100644 (file)
--- a/prng_gpu.tex
+++ b/prng_gpu.tex
@@ -74,11 +74,11 @@ numbers inside a GPU when a scientific application runs in a GPU. That is why we
 also provide  an efficient  PRNG for  GPU respecting based  on IC.  Such devices
 allows us to generated almost 20 billions of random numbers per second.
 
 also provide  an efficient  PRNG for  GPU respecting based  on IC.  Such devices
 allows us to generated almost 20 billions of random numbers per second.
 

-In order to establish 
+In order  to establish  that our  PRNGs are chaotic  according to  the Devaney's
+formulation, we extend what we have proposed in~\cite{guyeux10}. Moreover,  we define a new distance to measure the disorder in the chaos and we prove some interesting properties with this distance.

 
 The rest of this paper  is organised as follows. In Section~\ref{section:related
 
 The rest of this paper  is organised as follows. In Section~\ref{section:related

-  works}  we review  some GPU  implementions of  PRNG.  Section~\ref{sec:chaotic
-  iterations}  gives some  basic recalls  on  Devanay's formation  of chaos  and
+  works}  we review  some GPU  implementions of  PRNG.  Section~\ref{section:BASIC RECALLS}  gives some  basic recalls  on  Devanay's formation  of chaos  and

 chaotic iterations. In Section~\ref{sec:pseudo-random} the proof of chaos of our
 PRNGs  is  studied.   Section~\ref{sec:efficient  prng}  presents  an  efficient
 implementation of  our chaotic PRNG  on a CPU.   Section~\ref{sec:efficient prng
 chaotic iterations. In Section~\ref{sec:pseudo-random} the proof of chaos of our
 PRNGs  is  studied.   Section~\ref{sec:efficient  prng}  presents  an  efficient
 implementation of  our chaotic PRNG  on a CPU.   Section~\ref{sec:efficient prng


@@ -817,8 +817,8 @@ the larger the number of threads is,  the more local memory is used and the less
 branching  instructions are  used (if,  while, ...),  the better  performance is
 obtained  on  GPU.  So  with  algorithm  \ref{algo:seqCIprng}  presented in  the
 previous section, it is possible to  build a similar program which computes PRNG
 branching  instructions are  used (if,  while, ...),  the better  performance is
 obtained  on  GPU.  So  with  algorithm  \ref{algo:seqCIprng}  presented in  the
 previous section, it is possible to  build a similar program which computes PRNG

-on  GPU. In  the CUDA  [ref] environment,  threads have  a  local identificator,
-called \texttt{ThreadIdx} relative to the block containing them.
+on   GPU.  In  the   CUDA~\cite{Nvid10}  environment,   threads  have   a  local
+identificator, called \texttt{ThreadIdx} relative to the block containing them.

 
 
 \subsection{Naive version for GPU}
 
 
 \subsection{Naive version for GPU}


@@ -828,14 +828,14 @@ The principe consists in assigning the computation of a PRNG as in sequential to
 each thread  of the  GPU.  Of course,  it is  essential that the  three xor-like
 PRNGs  used for  our computation  have different  parameters. So  we  chose them
 randomly with  another PRNG. As the  initialisation is performed by  the CPU, we
 each thread  of the  GPU.  Of course,  it is  essential that the  three xor-like
 PRNGs  used for  our computation  have different  parameters. So  we  chose them
 randomly with  another PRNG. As the  initialisation is performed by  the CPU, we

-have chosen to use the ISAAC PRNG  [ref] to initalize all the parameters for the
-GPU version  of our  PRNG.  The  implementation of the  three xor-like  PRNGs is
-straightforward  as soon  as their  parameters have  been allocated  in  the GPU
-memory. Each xor-like  PRNGs used works with an internal  number $x$ which keeps
-the last generated random numbers. Other internal variables are also used by the
-xor-like PRNGs. More  precisely, the implementation of the  xor128, the xorshift
-and  the xorwow  respectively  require 4,  5  and 6  unsigned  long as  internal
-variables.
+have  chosen  to  use  the  ISAAC  PRNG~\ref{Jenkins96}  to  initalize  all  the
+parameters for  the GPU version  of our PRNG.   The implementation of  the three
+xor-like  PRNGs  is  straightforward  as  soon as  their  parameters  have  been
+allocated in  the GPU memory.  Each xor-like PRNGs  used works with  an internal
+number  $x$  which keeps  the  last  generated  random numbers.  Other  internal
+variables  are   also  used   by  the  xor-like   PRNGs.  More   precisely,  the
+implementation of the  xor128, the xorshift and the  xorwow respectively require
+4, 5 and 6 unsigned long as internal variables.

 
 \begin{algorithm}
 
 
 \begin{algorithm}
 


@@ -895,7 +895,7 @@ which represent the indexes of the  other threads for which the results are used
 by the  current thread. In  the algorithm, we  consider that a  64-bits xor-like
 PRNG is used, that is why both 32-bits parts are used.
 
 by the  current thread. In  the algorithm, we  consider that a  64-bits xor-like
 PRNG is used, that is why both 32-bits parts are used.
 

-This version also succeed to the BigCrush batteries of tests.
+This version also succeeds to the {\it BigCrush} batteries of tests.

 
 \begin{algorithm}
 
 
 \begin{algorithm}
 


@@ -954,22 +954,34 @@ Devaney's formulation of a chaotic behavior.
 \section{Experiments}
 \label{sec:experiments}
 
 \section{Experiments}
 \label{sec:experiments}
 

-Different experiments have been performed in order to measure the generation
-speed.
-\begin{figure}[t]
+Different experiments  have been  performed in order  to measure  the generation
+speed. We have used  a computer equiped with Tesla C1060 NVidia  GPU card and an
+Intel Xeon E5530 cadenced at 2.40 GHz for our experiments.
+
+In Figure~\ref{fig:time_gpu}  we compare the number of  random numbers generated
+per second.   In order  to obtain the  optimal number  we remove the  storage of
+random numbers  in the GPU memory. This  step is time consumming  and slows down
+the random number  generation.  Moreover, if you are  interested by applications
+that consome  random number directly when  they are generated,  their storage is
+completely useless. In this figure we can see that when the number of threads is
+greater than approximately  30,000 upto 5 millions the  number of random numbers
+generated per second is almost constant.   With the naive version, it is between
+2.5  and  3GSample/s.   With the  optimized  version,  it  is almost  equals  to
+20GSample/s.
+
+\begin{figure}[htbp]

 \begin{center}
   \includegraphics[scale=.7]{curve_time_gpu.pdf}
 \end{center}
 \caption{Number of random numbers generated per second}
 \begin{center}
   \includegraphics[scale=.7]{curve_time_gpu.pdf}
 \end{center}
 \caption{Number of random numbers generated per second}

-\label{fig:time_naive_gpu}
+\label{fig:time_gpu}

 \end{figure}
 
 
 \end{figure}
 
 

-First of all we have compared the time to generate X random numbers with both
-the CPU version and the GPU version. 
+In  comparison,   Listing~\ref{algo:seqCIprng}  allows  us   to  generate  about
+138MSample/s with only one core of the Xeon E5530.
+

 
 

-Faire une courbe du nombre de random en fonction du nombre de threads,
-éventuellement en fonction du nombres de threads par bloc.