1. 10 Apr, 2009 1 commit
    • Tejun Heo's avatar
      percpu: unbreak alpha percpu · 066123a5
      Tejun Heo authored
      
      
      For the time being, move the generic percpu_*() accessors to
      linux/percpu.h.
      
      asm-generic/percpu.h is meant to carry generic stuff for low level
      stuff - declarations, definitions and pointer offset calculation
      and so on but not for generic interface.
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      066123a5
  2. 09 Apr, 2009 1 commit
    • Heiko Carstens's avatar
      mutex: have non-spinning mutexes on s390 by default · 36cd3c9f
      Heiko Carstens authored
      
      
      Impact: performance regression fix for s390
      
      The adaptive spinning mutexes will not always do what one would expect on
      virtualized architectures like s390. Especially the cpu_relax() loop in
      mutex_spin_on_owner might hurt if the mutex holding cpu has been scheduled
      away by the hypervisor.
      
      We would end up in a cpu_relax() loop when there is no chance that the
      state of the mutex changes until the target cpu has been scheduled again by
      the hypervisor.
      
      For that reason we should change the default behaviour to no-spin on s390.
      
      We do have an instruction which allows to yield the current cpu in favour of
      a different target cpu. Also we have an instruction which allows us to figure
      out if the target cpu is physically backed.
      
      However we need to do some performance tests until we can come up with
      a solution that will do the right thing on s390.
      Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Cc: Christian Borntraeger <borntraeger@de.ibm.com>
      LKML-Reference: <20090409184834.7a0df7b2@osiris.boeblingen.de.ibm.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      36cd3c9f
  3. 08 Apr, 2009 2 commits
  4. 07 Apr, 2009 36 commits