cvs commit: src/sys/kern subr_param.c sys_pipe.c src/sys/sys pipe.h

Mike Silbersack silby at
Sat Mar 27 12:05:59 PST 2004

On Sat, 27 Mar 2004, Alan Cox wrote:

>   Log:
>   Revise the direct or optimized case to use uiomove_fromphys() by the reader
>   instead of ephemeral mappings using pmap_qenter() by the writer.  The
>   writer is still, however, responsible for wiring the pages, just not
>   mapping them.  Consequently, the allocation of KVA for the direct case is
>   unnecessary.  Remove it and the sysctls limiting it, i.e.,
>   kern.ipc.maxpipekvawired and kern.ipc.amountpipekvawired.  The number
>   of temporarily wired pages is still, however, limited by
>   kern.ipc.maxpipekva.

The best advantage of this change is that the workings of direct mapped
pipes make much more sense to those of us who are not VM experts. :)

Mike "Silby" Silbersack

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