cvs commit: src/sys/dev/ppbus pps.c

[Warner Losh]

imp         2005-04-14 15:56:10 UTC

  FreeBSD src repository

  Modified files:
    sys/dev/ppbus        pps.c 
  Log:
  In ppsintr, we needed ppsdev to get to the softc and nothing else.
  Save a memory dereference in the ISR by passing this in directly.
  Calling pps_capture is MP safe for all other operations on struct
  pps_state, so there's no need to aquire the lock before we do this,
  even from a fast ISR.  Avoid dereferencing sc->ppbus until after
  pps_capture is called as well.  These actions reduce somewhat the
  cache effects that cause variance in interrupt times.  On an
  especially slow test machine (300MHz Cyrix GXm), this reduces the
  interrupt latency about about 10% (from 21us to 19us) and helps a
  little with the variance (although most of the variance seems to be
  caused by lots of interrupt masking).
  
  This also happens fixes one or two of bde's style issues.
  
  Revision  Changes    Path
  1.50      +7 -11     src/sys/dev/ppbus/pps.c