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GeneralRe: I need help with win32 api edit controls Pin
Michael Dunn30-Jan-07 7:29
sitebuilderMichael Dunn30-Jan-07 7:29 
QuestionNeed help with CXX0033: Error: error in OMF type information Pin
Sebastian Schneider29-Jan-07 23:48
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AnswerRe: Need help with CXX0033: Error: error in OMF type information Pin
Sebastian Schneider30-Jan-07 1:37
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QuestionReading disk data from multiple processes. Pin
Bartosz Bien29-Jan-07 22:08
Bartosz Bien29-Jan-07 22:08 
JokeRe: Reading disk data from multiple processes. Pin
Nibu babu thomas29-Jan-07 22:14
Nibu babu thomas29-Jan-07 22:14 
GeneralRe: Reading disk data from multiple processes. Pin
Bartosz Bien29-Jan-07 22:28
Bartosz Bien29-Jan-07 22:28 
AnswerRe: Reading disk data from multiple processes. Pin
Michael Dunn29-Jan-07 22:38
sitebuilderMichael Dunn29-Jan-07 22:38 
AnswerRe: Reading disk data from multiple processes. Pin
James R. Twine30-Jan-07 1:08
James R. Twine30-Jan-07 1:08 
   I would guess that the load times are increased because the drive is having to jump back and forth on the disk to find un-cached data.

   Depending on the size of the data, if it is the same data or different data for each process, and the type of reading going on (sequential vs. random), some of the following might work:

     1: Use a memory mapped file (MMF) - this eliminates the secondary memory buffer (and possibly "chunking") normally used to read data from disk.  Internally, file data is also paged-in in the most efficient manner.  Multiple processes can even use the same memory mapped object (if it is named), reducing the overhead of creating and destroying the file object within each object.

     2: You can also use a MMF to create a private cache for the file data.  You can create a pagefile-based MMF, which is basically a shared memory implementation, copy the file-based data into the MMF's memory, and then share it across all of the processes.  While there will be some paging taking place, it should still be much less than that involved for hitting the disk for the pagefile and the on-disk data each time.

     3: Regardless of going the MMF route or not, if reading sequentially use the appropriate flags when calling ::CreateFile(...) to improve read performance.

     4: If not using a MMF solution, having each process read that file one-at-a-time sequentially from beginning to end, should offer a performance benefit as well.

   Peace!

-=- James
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QuestionAuto view CD Pin
hoa_nguyen29-Jan-07 21:59
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QuestionStandalone MFC/SDI App with static linking Pin
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