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Topic: Block size


  
  cutting cinder block
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www.cutting-cinder-block.com   (261 words)

  
  Block size (cryptography) - Wikipedia, the free encyclopedia
Both the input (plaintext) and output (ciphertext) are the same length; the output cannot be shorter than the input — this is logically required by the Pigeonhole principle and the fact that the cipher must be invertible — and it is simply undesireable for the output to be longer than the input.
Until the announcement of NIST's AES contest, the majority of block ciphers followed the example of the DES in using a block size of 64 bits (8 bytes).
The winner of the AES contest, Rijndael, supports block sizes of 128, 192, and 256 bits, although the extra block sizes were not adopted by the AES standard.
en.wikipedia.org /wiki/Block_size_(cryptography)   (370 words)

  
 Block cipher - Wikipedia, the free encyclopedia   (Site not responding. Last check: 2007-10-19)
In cryptography, a block cipher is a symmetric key cipher which operates on fixed-length groups of bits, termed blocks, with an unvarying transformation.
Block ciphers can be contrasted with stream ciphers; a stream cipher operates on individual digits one at a time, and the transformation varies during the encryption.
The block size, n, is typically 64 or 128 bits, although some ciphers have a variable block size.
en.wikipedia.org /wiki/Block_cipher   (937 words)

  
 GNU Core-utils: Block size   (Site not responding. Last check: 2007-10-19)
The default block size is chosen by examining the following environment variables in turn; the first one that is set determines the block size.
This specifies the default block size for the
Integers may be followed by suffixes that are upward compatible with the SI prefixes for decimal multiples and with the IEC 60027-2 prefixes for binary multiples.
www.gnu.org /software/coreutils/manual/html_node/coreutils_4.html   (383 words)

  
 Log block size   (Site not responding. Last check: 2007-10-19)
Although the size of redo entries is measured in bytes, LGWR writes the redo to the log files on disk in blocks.
The log block size is the unit for the setting of the log_checkpoint_interval, _log_io_size and max_dump_file_size parameters.
There is a 16 byte header for each log block, and the size of the data area is approximately the number of bytes of redo generated (redo size) plus the number of bytes of redo space left unused (redo wastage) divided by the number of log blocks written (redo blocks written).
www.ixora.com.au /notes/log_block_size.htm   (322 words)

  
 Info Node: (coreutils.info)Block size
For `ls' file sizes, the block size defaults to 1 byte.
A block size specification can be a positive integer specifying the number of bytes per block, or it can be `human-readable' or `si' to select a human-readable format.
With human-readable formats, output sizes are followed by a size letter such as `M' for megabytes.
www.cs.vassar.edu /cgi-bin/info.cgi?(coreutils)Block+size   (536 words)

  
 Block Ciphers
The general operation of all block ciphers is the same - a given number of bits of plaintext (a block) is encrypted into a block of ciphertext of the same size.
The disadvantage of CBC is that the encryption of a data block becomes dependent on all the blocks prior to it.
To decrypt, the ciphertext is broken into L and R blocks, and the key and the R block are run through the hash function to get the same hash result used in the last cycle of encryption; notice that the R block was unchanged in the last encryption cycle.
www.freesoft.org /CIE/Topics/143.htm   (1497 words)

  
 Block-size of 2,500,000 terms
The block size is : 2500000 terms Total number of blocks used: 1238 Total number of terms in the series: 3095000000 Computed value of pi : 3.14159265349124e+00 Machine value of pi : 3.14159265358979e+00 difference : 0.00000000009856 difference : 9.85553860743948e-11 Total execution time is : 55.957 seconds.
The block size is : 2500000 terms Total number of blocks used: 1238 Total number of terms in the series: 3095000000 Computed value of pi : 3.14159265349123e+00 Machine value of pi : 3.14159265358979e+00 difference : 0.00000000009856 difference : 9.85647119478017e-11 Total execution time is : 30.848 seconds.
The block size is : 2500000 terms Total number of blocks used: 1240 Total number of terms in the series: 3100000000 Computed value of pi : 3.14159265349472e+00 Machine value of pi : 3.14159265358979e+00 difference : 0.00000000009507 difference : 9.50732825799605e-11 Total execution time is : 16.676 seconds.
www.cs.iastate.edu /~cs425/homework/Example/node11.html   (354 words)

  
 Block-size of 5,000,000 terms
The block size is : 5000000 terms Total number of blocks used: 619 Total number of terms in the series: 3095000000 Computed value of pi : 3.14159265349072e+00 Machine value of pi : 3.14159265358979e+00 difference : 0.00000000009907 difference : 9.90700854686111e-11 Total execution time is : 55.930 seconds.
The block size is : 5000000 terms Total number of blocks used: 620 Total number of terms in the series: 3100000000 Computed value of pi : 3.14159265349421e+00 Machine value of pi : 3.14159265358979e+00 difference : 0.00000000009558 difference : 9.55786561007699e-11 Total execution time is : 29.578 seconds.
The block size is : 5000000 terms Total number of blocks used: 620 Total number of terms in the series: 3100000000 Computed value of pi : 3.14159265349421e+00 Machine value of pi : 3.14159265358979e+00 difference : 0.00000000009558 difference : 9.55791001899797e-11 Total execution time is : 15.352 seconds.
www.cs.iastate.edu /~cs425/homework/Example/node12.html   (354 words)

  
 Use a large database block size
The degree of block chaining in the data dictionary clusters is reduced, as is the risk of block chaining in hash clusters used by the application for efficient primary key based look ups.
The size of the transaction tables in the rollback segment header blocks is increased.
Also, because using a smaller block size for tables reduces the data density, increases the risk of chaining, and makes sequential processing less efficient, there are many cases in which it is better to follow the general principle of using a large block size.
www.ixora.com.au /tips/block_size.htm   (1346 words)

  
 Choice of Block Size
The computational blocking factor is chosen to be the same as the distribution block size.
Therefore, the larger the block size, the greater the necessary workspace, i.e the smaller the largest solvable problem on a given grid of processes.
Therefore, it is good practice to choose the block size to be the problem size for which the BLAS matrix-multiply GEMM routine achieves 90 % of its reachable peak.
www.netlib.org /utk/papers/sc96-scalapack/NODE22.HTM   (453 words)

  
 What is tape block size of 0?   (Site not responding. Last check: 2007-10-19)
as fixed block size, whether it is or not.
size, and the size passed to write becomes the physical block size.
Then if you use a sensible block size to dd, all should be wonderful.
www.unixguide.net /ibm/faq/faq1.205.shtml   (169 words)

  
 RSA Security - 2.1.4 What is a block cipher?
A block cipher is a type of symmetric-key encryption algorithm that transforms a fixed-length block of plaintext (unencrypted text) data into a block of ciphertext (encrypted text) data of the same length.
The fixed length is called the block size, and for many block ciphers, the block size is 64 bits.
For those with a mathematical background (see Appendix A): Since different plaintext blocks are mapped to different ciphertext blocks (to allow unique decryption), a block cipher effectively provides a permutation (one to one reversible correspondence) of the set of all possible messages.
www.rsasecurity.com /rsalabs/node.asp?id=2168   (342 words)

  
 Memory Hierarchy with a Variable Block Size   (Site not responding. Last check: 2007-10-19)
The use of individual words within a block as well as the presence of an "adjecent" block of the same size are used to indicate whether to grow or shrink the block by a factor of 2x.
Block size is allowed to vary from 8B to 256B for L1 caches and 64B to 512B for the L2 caches.
In this case the decision to change the block size is made by software, the hardware simply supports multiple sizes and has an interface allowing the software to change it.
www.ics.uci.edu /~alexv/Adaptive.html   (475 words)

  
 AskTom "Recommendations on Block Size"   (Site not responding. Last check: 2007-10-19)
You now have to size buffer caches for each individual type (and a buffer cache is a pretty impressively robust thing -- it keeps that which you use and loses that which you don't).
Additionally the 4k block size would not be my first choice for this database, but changing it is a medium- to long-term strategy.
IMHO, this case calls for 4k block size to reduce amount of dbwr writes to disk (because dbwr is working in a blocks).
asktom.oracle.com /pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:37335239610842   (1186 words)

  
 Block Size.   (Site not responding. Last check: 2007-10-19)
As the block size increases, the length of the Arnoldi reduction
One of the benefits of block methods is that they are more reliable for computing approximations to the clustered and/or multiple eigenvalues using a relatively large convergence criterion.
Note that the block size used may be varied during each restart.
www.cs.utk.edu /~dongarra/etemplates/node238.html   (144 words)

  
 Hydrogenaudio Forums -> Block size of various AAC coders
I understood that the block size was 1024 samples for a long block and 128 samples for a short block.
In a 3GPP paper that describes the enhanced AAC + coder, the block size is 2048 samples for a long block and 256 samples for a short block.
So, 2048/256 are the sizes of the transform windows and 1024/128 are actually the block sizes.
www.hydrogenaudio.org /forums/index.php?showtopic=28263   (403 words)

  
 Oracle9i multiple block size blocksize db_cache_size
Prior to Oracle9i, your entire Oracle database had to have a single block size and this block size was determined at the time that the database was created.
Remember, the block size of the data dictionary is not as important as ensuring that the data buffer associated with the SYSTEM tablespace has enough RAM to fully-cache all data dictionary blocks.
Average row length determines block size - The block size for a tables’ tablespace should always be greater than the average row length for the table (dba_tables.avg_row_len).
www.oracle-training.cc /oracle_tips_block_sizes.htm   (590 words)

  
 Huge Block Size Discussion
Thus, if we have a large block, ECB becomes practical, which could be useful in certain situations, and this *is* evidence that the ciphering block size could usefully be larger.
The very need to chain small blocks is itself mainly a consequence of tiny block size, and its general use an admission of the known weakness of small blocks.
Block ciphers with small block sizes are more versitile, and we know all about using feedback mechanisms to encrypt large blocks of plaintext will small block ciphers.
www.ciphersbyritter.com /NEWS/HUGEBLK.HTM   (20064 words)

  
 Determining the Block Size for Block Algorithms   (Site not responding. Last check: 2007-10-19)
The intention behind the design of LAPACK is that the choice of block size should be hidden from users as much as possible, but at the same time easily accessible to installers of the package when tuning LAPACK for a particular machine.
Some LAPACK routines require a work array whose size is proportional to the block size (see subsection 5.1.7).
Thus, the routine uses the largest block size allowed by the amount of workspace supplied, as long as this is likely to give better performance than the unblocked algorithm.
www.go.dlr.de:8081 /pdinfo_dv/lapack_lug_dlr/node120.html   (481 words)

  
 mhash_get_block_size
mhash_get_block_size -- Get the block size of the specified hash
is used to get the size of a block of the specified
and returns the size in bytes or false, if the
www.norrnod.se /norrnod/dokumentation/php3/function.mhash-get-block-size.html   (32 words)

  
 [hfs-user] Device (Driver) Descriptor Block and block size   (Site not responding. Last check: 2007-10-19)
This block size is only used in this DDB and in the partition table (the fourth unsigned long).
This block size doesn't have anything to do with the allocation block/cluster size, that is with the size of the chunks used to manage the data space in the allocation bitmaps.
For such volumes, keeping the allocation block size to 0x800 bytes is an advantage, in particular if you build hybrid data structures with an ISO/Joliet catalog pointing to the same data pool.
www.mars.org /mailman/public/hfs-user/2004/000364.html   (430 words)

  
 Database block size = File system buffer size
If the database block size is smaller than the file system buffer size, then DBWn has to perform partial block writes.
(Foreground processes are seldom directly affected by partial block writes because their writes, normally to temporary segments, are typically large relative to the database block size).
If the database block size is larger than the file system buffer size, then all single block reads and writes are split into a series of distinct physical I/O operations - one for each file system buffer addressed - and these I/O operations are performed one at a time.
www.ixora.com.au /tips/buffered_block_size.htm   (424 words)

  
 ► » I/O Block Size   (Site not responding. Last check: 2007-10-19)
On our AIX boxes the I/O block size is 512bytes.
Block: A contiguous, 512-byte region of a physical volume that
The default block size is 4096 bytes, since
www.all-unix.org /-IO-Block-Size-9145302.html   (121 words)

  
 Line (Block) Size Choice for CPU Cache Memories   (Site not responding. Last check: 2007-10-19)
The line (block) size of a cache memory is one of the parameters that most strongly affects cache performance.
The change in cache miss ratio as the line size varies is found to be relatively stable across workloads, and tables of this function are presented for instruction caches, data caches, and unified caches.
Longer line sizes are suitable for mainframes because of the higher bandwidth to main memory.
sunsite.berkeley.edu /TechRepPages/CSD-85-239   (312 words)

  
 5.3.4 Effect of block size   (Site not responding. Last check: 2007-10-19)
The relative locality of memory references of various programs is reflected in the block size at which the corresponding miss rate is minimum.
Notice that, for SIS the decrease in miss rate with the increase in block size is quite dramatic.
Contrasting this with the behavior in the previous subsection, we conclude that the cache size increase and block size increase affect the miss rate in different ways for different programs.
www-cad.eecs.berkeley.edu /~rajeev/cs252/report/main/node30.html   (189 words)

  
 3-Way
3-Way has a block size of 96 bits, notably not a power of two such as the more common 64 or 128 bits.
The figure 96 arises from the use of three 32 bit words in the algorithm, from which also is derived the cipher's name.
When 3-Way was invented, 96-bit keys and blocks were quite strong, but more recent ciphers have a 128-bit block, and few now have keys shorter than 128 bits.
encycl.opentopia.com /term/3-Way   (219 words)

  
 Wavelet Regression via Block Thresholding: Adaptivity and the Choice of Block Size and Threshold Level - Cai ...   (Site not responding. Last check: 2007-10-19)
Abstract: We consider block thresholding rules for wavelet regression and derive an "optimal " block thresholding estimator that is fully specified and easy to implement, at a computational cost of O(n).
The results show that there are conflicting requirements on block size for achieving the global and local adaptivity.
Wavelet regression via block thresholding: adaptivity and the choice of block size and threshold level.
citeseer.ist.psu.edu /207142.html   (657 words)

  
 Block Size on RAID Disk Array? - TechIMO Forums
I would think that 16 would waste less space since the total #/size of the blocks could be within 16k of the actual size of the data.
It indicates that a small block size would be used for a file server where there were numerous small files.
A medium block size is used for a typical home computer where there is usually a combination of both large and small files.
www.techimo.com /forum/showthread.php?t=69897   (790 words)

  
 [mythtv] Re: [PATCH] Increase block size
1st safe_read request blocks 1,2,3 return block 1 2nd safe_read block 2 and part of 3 available request block 4 return block 2 3rd safe_read block 3 and part of 4 available request block 5 return block 3 This way safe_read would never stall because there were more bytesAvailable than the current read.
If the block size was 64000 it would again take 0.25sec.
An unstated benefit of the QSD patch was that the smaller block size sped up channel changes for everyone to various degrees but, as you are well aware, the smaller block size caused other problems at higher bitrates.
www.mythtv.org /pipermail/mythtv-dev/2003-December/017098.html   (873 words)

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