PIPE_SIZE aspects

[Ad van den Broek]

I searched the net regarding PIPE_SIZE aspects.
This is what I found:

* The constant PIPE_SIZE
establishes the number of bytes allocated for a pipe
(the size of the pipe buffer)

* The default of PIPE_SIZE (in Linux 2.4) is PAGE_SIZE.
* The default of PIPE_SIZE (in Linux 2.6) is 64K.

* PAGE_SIZE (in Linux 2.4) is CPU/hw depending,
  may not be changed and is 4K for x86.
* PAGE_SIZE (in Linux 2.6) is 64K.

* PIPE_SIZE can be changed in Linux 2.4,
  but it should be NOT larger than PAGE_SIZE
  or a patch should be implemented

 I found a patch (I believe the author is Julian Bradfield) at
 http://lse.sourceforge.net/pipe/2.4.9-pipe.patch
 and this patch is modified by Manfred Spraul which version can be found at
 http://linuxperf.sourceforge.net/patches/2.4.13-largepipe.patch
 It is tested with PIPE_SIZE from 1 upto 2,4,8 pages.
 and the result is at http://lse.sourceforge.net/pipe/pipe-report.txt


My questions:
 Is the above info correct ?
 Is the large pipe patch still correct for last 2.4.x versions ?
 Is such a patch also required/possible in Linux 2.6
 to allow PIPE_SIZE > PAGE_SIZE or is that different in 2.6 ?



-- 

With best regards,
Ad van den Broek
The Netherlands
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