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

[Alan Cox]

On Sat, Mar 27, 2004 at 02:05:56PM -0600, Mike Silbersack wrote:
> 
> 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. :)
> 

I hope this also serves to motivate people to work on eliminating the
buffer map.  Consider uiomove_fromphys() as my contribution to that
effort.  :-)

Alan