statement expresses more than one idea, then
you might confuse your readers about the
subject of your paper. For example: Companies
need to exploit the marketing potential of the
Internet, and Web pag
in non-decreasing order in each node, and nondecreasing order between nodes. More
precisely, this means that Ep,i Ep, j for all
relevant i < j and p, and that Ep,i Eq, j for 0 p
< q < P and all releva
degree of efficiency. Merging algorithms that
require less memory are possible but they are
quite computationally expensive[Ellis and
Markov 1998; Huang and Langston 1988;
Kronrod 1969]. 1.1.2.2 Exten
remote update algorithm 57 of the fast
signature11. A 16 bit index table is then formed
which takes a 16 bit hash value and gives an
index into the sorted signature table which
points to the first ent
message digest algorithms commonly used in
cryptographic applications. These algorithms
are believed to have the following properties
(where b is the number of bits in the signature)
[Schneier 1996]:
the first pass when sorting 50 million 64 bit
random elements on the 128 processor AP1000
for varying values of k. Note the narrow y range
on the graph. The results show that even for
quite high value
files to be transferred through my modem for
archiving, distribution or testing on computers
at the other end of the link or on the other side
of the world. The time taken to transfer the
changes gave
sorting we can perform some simple
calculations which are very revealing and which
provide a great deal of guidance in the
algorithm design. It is well known that
comparison-based sorting algorithms o
not a problem except when disk space is very
tight. Even without this restriction it would, in
many cases, be wise for the reconstruction to
happen to a temporary file followed by an
atomic rename as
[1] [0 1]). 6A method for avoiding infinitypadding using balancing is given in Section 1.2.5
so infinity-padding is not strictly needed but it
provides some useful concepts nonetheless.
1.2 Algorithm
and Plaxton 1993] and demonstrate that it is
asymptotically optimal in terms of I/O
operations on general multi-level storage
hierarchies. Their algorithm is aimed at larger
values of k than are consi
investigation of fast signature algorithms which
depended on all the bytes in a block, while
requiring very little computation to find the
signature values for every byte offset in a file.
Perhaps the
Get International Experience during your Studies!
SAMK has wide international connections and partner universities in various countries. All the
students of SAMK have a change to go abroad as an excha
nomenclature a little. 2Unless the link is
asymmetric. If the link was very fast from B to A
but slow from A to B then it wouldnt matter
how big S is. 3.2 Designing a remote update
algorithm 51 means
than the other node, then the virtual infinity
elements are all required in the other node, and
no transfer of real elements is required. This
means that if a final balancing phase is
introduced where
1.2.12 we dont strictly need to obtain a sorted
list in each cell when this two processor merge
is being used as part of a larger parallel merge
but it does simplify the discussion. 1.1 How
fast can i
nodes in a MIMD machine. To obtain good
memory utilization when sorting small
elements linked lists are avoided. Thus, the lists
of elements referred to below are implemented
using arrays, without any
algorithm unusable. For example, the signature
could be just the first 4 bytes of each block. This
would be very easy to compute but the
algorithm would fail to produce the right result
when two diffe
N P logP) time. 1.1.2.1 The two processor
problem Let us first consider the simplest
possible parallel merging problem, where we
have just two processors and each processor
starts with N 2 elements. T
will transfer the whole file. 3.2.2 A second try
We can solve this problem by getting A to
generate signatures not just at block
boundaries, but at all byte boundaries. When A
compares the signature a
we have implicitly performed padding of the
nodes with infinity elements, thus guaranteeing
the correct behavior of the algorithm. 1.2.4
Balancing The aim of the balancing phase of the
algorithm is to
varied links within this relatively new discipline.
I hope you will enjoy reading it as much as I
enjoyed the research which it describes.
Chapter 1 Internal Parallel Sorting My first
introduction to
thoroughly enjoyable. That enjoyment is largely
a result of the interaction that I have had with
my supervisors, colleagues and, in the case of
rsync, the people who have tested and used the
resulting
totally lacked a parallel sorting routine. I had
been expecting that there would be a routine
that is the parallel equivalent of the ubiquitous
qsort() routine found in standard C libraries.
The lack
signature table then a single byte literal is
emitted and the search continues at the next
byte13 . At first glance this search algorithm
appears to be O(n 2 ) in the file size, because for
a fixed bl
showing how it can be implemented with
minimal memory overhead. Each stage of the
algorithm is analyzed more carefully resulting in
a more accurate estimate of the expected
running time of the algorit
in the next chapter. 14It rises as n or n
depending on the definition of optimal. 3.3
Choosing the block size 58 some extra memory
and bookkeeping. 3.2.7 Reconstructing the file
One of the simplest pa
A and uses these to construct ai . For this
algorithm to be effective and efficient we need
the following conditions: the signature R
needs to be cheap to compute at every byte
offset in a file; 6 I c