cvs commit: src/sys/sys xio.h src/sys/kern kern_xio.c

[Matthew Dillon]

dillon      2004/03/31 11:24:17 PST

DragonFly src repository

  Added files:
    sys/sys              xio.h 
    sys/kern             kern_xio.c 
  Log:
  Initial XIO implementation.  XIOs represent data through a list of VM pages
  rather then mapped KVM, allowing them to be passed between threads without
  having to worry about KVM mapping overheads, TLB invalidation, and so forth.
  
  This initial implementation supports creating XIOs from user or kernel data
  and copying from an XIO to a user or kernel buffer or a uio.  XIO are intended
  to be used with CAPS, PIPES, VFS, DEV, and other I/O paths.
  
  The XIO concept is an outgrowth of Alan Cox'es unique use of target-side
  SF_BUF mapping to improve pipe performance.