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Subject: Re: Is this true?

Author: Robert Hyatt

Date: 05:51:59 04/25/00

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On April 25, 2000 at 07:21:57, Laurence Chen wrote:

>On April 25, 2000 at 03:26:55, Jouni Uski wrote:
>
>>Even if You have dual prosessor mainboard and Windows NT You can't play
>>engine-engine matches with ponder on!? Reason: if both engines are using same TB
>>path so there is conflict, when they access them simultaneously...
>>
>>Jouni
>I find this hard to believe.  Does anyone has proof?  From my own experience, I
>know that multiple users can read the same files, but only one user can write to
>the file.  If a file is open for editing, all other users can only read it.
>Laurence


That isn't the real issue.  A disk is a serially-accessible device.  If I do
a read, my process blocks waiting on the I/O.  If you do a read, you block
waiting on (a) for me to finish my I/O, then you stay blocked waiting on the
drive itself.  I don't think this is serious since both are affected in a
similar way.  And once you read the database, if the other program needs the
same block (not too uncommon) then the file cache will avoid the second read,
and the associated penalty.



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