cvs commit: src/sys/dev/vinum vinumrequest.c vinumvar.h

[Stephen McKay]

mckay       2004-12-12 04:10:52 UTC

  FreeBSD src repository

  Modified files:        (Branch: RELENG_4)
    sys/dev/vinum        vinumrequest.c vinumvar.h 
  Log:
  Merge from, um, oblivion: vinumvar.h 1.49, vinumrequest.c 1.73
  
      When doing round-robin reads from a multi-plex volume, only switch to the
      next plex if the sector to be read isn't nearby the last read sector.
  
      Submitted by:  Vsevolod Lobko <seva at ip.net.ua> via ru@
  
  Not only does this boost multi-access performance, but surprisingly it helps
  single process sequential reads on my IDE disk mirror.  My guess is that the
  read-a-block skip-a-block read-a-block effect of strict round-robin defeats
  some sort of on-disk caching, leading to poor performance.  With this patch,
  longer contiguous reads from a single disk are more common.
  
  /sbin/vinum needs to be rebuilt as this patch changes the size of struct plex.
  
  OK'd by: grog
  
  Revision  Changes    Path
  1.44.2.6  +12 -4     src/sys/dev/vinum/vinumrequest.c
  1.32.2.5  +9 -1      src/sys/dev/vinum/vinumvar.h