Increasing MAXPHYS

Alan Cox alan.l.cox at gmail.com
Sat Mar 20 19:38:19 UTC 2010


2010/3/20 Alexander Motin <mav at freebsd.org>

> Hi.
>
> With set of changes done to ATA, CAM and GEOM subsystems last time we
> may now get use for increased MAXPHYS (maximum physical I/O size) kernel
> constant from 128K to some bigger value.


[snip]


> All above I have successfully tested last months with MAXPHYS of 1MB on
> i386 and amd64 platforms.
>
> So my questions are:
> - does somebody know any issues denying increasing MAXPHYS in HEAD?
> - are there any specific opinions about value? 512K, 1MB, MD?
>
>
For now, I think it should machine-dependent.  The virtual memory system
should have no problems with MAXPHYS of 1MB on amd64 and ia64.

Alan


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