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Use hardcoded 8192 for PIPE_MINDIRECT, rather than being dependant 

on PAGE_SIZE. The overhead of setting up Page Loan is pretty much constant
irregardless of page size, so it makes more sense to use fixed constant.

According to hbench, the overhead of Page Loan setup is still significantly
bigger than the performance gain for 4096 byte buffers on i386
(PIII/600Mhz). The difference is smaller on 386DX, but Page Loan is
still not faster for this case.

Also, there is some other code out there which expects 4KB writes
to not block even for 'blocking' write, since it works this
way on some other operating systems.
Partially addresses kern/14246 by Andreas Persson.
This commit is contained in:
jdolecek 2001-10-28 20:27:55 +00:00
parent a58e0c8a53
commit 47ea6cbd85
1 changed files with 0 additions and 4 deletions
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4
sys/sys/pipe.h
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@ -62,11 +62,7 @@
* than PIPE_BUF.
*/
#ifndef PIPE_MINDIRECT
#if defined(__FreeBSD__)
#define PIPE_MINDIRECT 8192
#elif defined(__NetBSD__)
#define PIPE_MINDIRECT PAGE_SIZE
#endif
#endif
/*