1. 18 Feb, 2008 1 commit
    • Jeremy Kerr's avatar
      [POWERPC] spufs: fix scheduler starvation by idle contexts · 4ef11014
      Jeremy Kerr authored
      2.6.25 has a regression where we can starve the scheduler by creating
      (N_SPES+1) contexts, then running them one at a time.
      
      The final context will never be run, as the other contexts are loaded on
      the SPEs, none of which are repoted as free (ie, spu->alloc_state !=
      SPU_FREE), so spu_get_idle() doesn't give us a spu to run on. Because
      all of the contexts are stopped, none are descheduled by the scheduler
      tick, as spusched_tick returns if spu_stopped(ctx).
      
      This change replaces the spu_stopped() check with checking for SCHED_IDLE
      in ctx->policy. We set a context's policy to SCHED_IDLE when we're not
      in spu_run(). We also favour SCHED_IDLE contexts when looking for contexts
      to unbind, but leave their timeslice intact for later resumption.
      
      This patch fixes the following test in the spufs-testsuite:
        tests/20-scheduler/02-yield-starvation
      Signed-off-by: default avatarJeremy Kerr <jk@ozlabs.org>
      4ef11014
  2. 15 Feb, 2008 39 commits