1. 10 5月, 2010 2 次提交
  2. 08 5月, 2010 1 次提交
    • T
      cpu_stop: add dummy implementation for UP · bbf1bb3e
      Tejun Heo 提交于
      When !CONFIG_SMP, cpu_stop functions weren't defined at all which
      could lead to build failures if UP code uses cpu_stop facility.  Add
      dummy cpu_stop implementation for UP.  The waiting variants execute
      the work function directly with preempt disabled and
      stop_one_cpu_nowait() schedules a workqueue work.
      
      Makefile and ifdefs around stop_machine implementation are updated to
      accomodate CONFIG_SMP && !CONFIG_STOP_MACHINE case.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Reported-by: NIngo Molnar <mingo@elte.hu>
      bbf1bb3e
  3. 07 5月, 2010 3 次提交
    • T
      sched: replace migration_thread with cpu_stop · 969c7921
      Tejun Heo 提交于
      Currently migration_thread is serving three purposes - migration
      pusher, context to execute active_load_balance() and forced context
      switcher for expedited RCU synchronize_sched.  All three roles are
      hardcoded into migration_thread() and determining which job is
      scheduled is slightly messy.
      
      This patch kills migration_thread and replaces all three uses with
      cpu_stop.  The three different roles of migration_thread() are
      splitted into three separate cpu_stop callbacks -
      migration_cpu_stop(), active_load_balance_cpu_stop() and
      synchronize_sched_expedited_cpu_stop() - and each use case now simply
      asks cpu_stop to execute the callback as necessary.
      
      synchronize_sched_expedited() was implemented with private
      preallocated resources and custom multi-cpu queueing and waiting
      logic, both of which are provided by cpu_stop.
      synchronize_sched_expedited_count is made atomic and all other shared
      resources along with the mutex are dropped.
      
      synchronize_sched_expedited() also implemented a check to detect cases
      where not all the callback got executed on their assigned cpus and
      fall back to synchronize_sched().  If called with cpu hotplug blocked,
      cpu_stop already guarantees that and the condition cannot happen;
      otherwise, stop_machine() would break.  However, this patch preserves
      the paranoid check using a cpumask to record on which cpus the stopper
      ran so that it can serve as a bisection point if something actually
      goes wrong theree.
      
      Because the internal execution state is no longer visible,
      rcu_expedited_torture_stats() is removed.
      
      This patch also renames cpu_stop threads to from "stopper/%d" to
      "migration/%d".  The names of these threads ultimately don't matter
      and there's no reason to make unnecessary userland visible changes.
      
      With this patch applied, stop_machine() and sched now share the same
      resources.  stop_machine() is faster without wasting any resources and
      sched migration users are much cleaner.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Acked-by: NPeter Zijlstra <peterz@infradead.org>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Dipankar Sarma <dipankar@in.ibm.com>
      Cc: Josh Triplett <josh@freedesktop.org>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Dimitri Sivanich <sivanich@sgi.com>
      969c7921
    • T
      stop_machine: reimplement using cpu_stop · 3fc1f1e2
      Tejun Heo 提交于
      Reimplement stop_machine using cpu_stop.  As cpu stoppers are
      guaranteed to be available for all online cpus,
      stop_machine_create/destroy() are no longer necessary and removed.
      
      With resource management and synchronization handled by cpu_stop, the
      new implementation is much simpler.  Asking the cpu_stop to execute
      the stop_cpu() state machine on all online cpus with cpu hotplug
      disabled is enough.
      
      stop_machine itself doesn't need to manage any global resources
      anymore, so all per-instance information is rolled into struct
      stop_machine_data and the mutex and all static data variables are
      removed.
      
      The previous implementation created and destroyed RT workqueues as
      necessary which made stop_machine() calls highly expensive on very
      large machines.  According to Dimitri Sivanich, preventing the dynamic
      creation/destruction makes booting faster more than twice on very
      large machines.  cpu_stop resources are preallocated for all online
      cpus and should have the same effect.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Acked-by: NRusty Russell <rusty@rustcorp.com.au>
      Acked-by: NPeter Zijlstra <peterz@infradead.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Dimitri Sivanich <sivanich@sgi.com>
      3fc1f1e2
    • T
      cpu_stop: implement stop_cpu[s]() · 1142d810
      Tejun Heo 提交于
      Implement a simplistic per-cpu maximum priority cpu monopolization
      mechanism.  A non-sleeping callback can be scheduled to run on one or
      multiple cpus with maximum priority monopolozing those cpus.  This is
      primarily to replace and unify RT workqueue usage in stop_machine and
      scheduler migration_thread which currently is serving multiple
      purposes.
      
      Four functions are provided - stop_one_cpu(), stop_one_cpu_nowait(),
      stop_cpus() and try_stop_cpus().
      
      This is to allow clean sharing of resources among stop_cpu and all the
      migration thread users.  One stopper thread per cpu is created which
      is currently named "stopper/CPU".  This will eventually replace the
      migration thread and take on its name.
      
      * This facility was originally named cpuhog and lived in separate
        files but Peter Zijlstra nacked the name and thus got renamed to
        cpu_stop and moved into stop_machine.c.
      
      * Better reporting of preemption leak as per Peter's suggestion.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Acked-by: NPeter Zijlstra <peterz@infradead.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Dimitri Sivanich <sivanich@sgi.com>
      1142d810
  4. 28 4月, 2010 1 次提交
  5. 25 4月, 2010 2 次提交
  6. 24 4月, 2010 1 次提交
  7. 23 4月, 2010 2 次提交
  8. 22 4月, 2010 4 次提交
  9. 20 4月, 2010 2 次提交
  10. 19 4月, 2010 2 次提交
  11. 16 4月, 2010 1 次提交
  12. 15 4月, 2010 1 次提交
  13. 14 4月, 2010 2 次提交
    • D
      rcu: Better explain the condition parameter of rcu_dereference_check() · c08c68dd
      David Howells 提交于
      Better explain the condition parameter of
      rcu_dereference_check() that describes the conditions under
      which the dereference is permitted to take place (and
      incorporate Yong Zhang's suggestion).  This condition is only
      checked under lockdep proving.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: laijs@cn.fujitsu.com
      Cc: dipankar@in.ibm.com
      Cc: mathieu.desnoyers@polymtl.ca
      Cc: josh@joshtriplett.org
      Cc: dvhltc@us.ibm.com
      Cc: niv@us.ibm.com
      Cc: peterz@infradead.org
      Cc: rostedt@goodmis.org
      Cc: Valdis.Kletnieks@vt.edu
      Cc: eric.dumazet@gmail.com
      LKML-Reference: <1270852752-25278-2-git-send-email-paulmck@linux.vnet.ibm.com>
      Signed-off-by: NIngo Molnar <mingo@elte.hu>
      c08c68dd
    • P
      rcu: Add rcu_access_pointer and rcu_dereference_protected · b62730ba
      Paul E. McKenney 提交于
      This patch adds variants of rcu_dereference() that handle
      situations where the RCU-protected data structure cannot change,
      perhaps due to our holding the update-side lock, or where the
      RCU-protected pointer is only to be fetched, not dereferenced.
      These are needed due to some performance concerns with using
      rcu_dereference() where it is not required, aside from the need
      for lockdep/sparse checking.
      
      The new rcu_access_pointer() primitive is for the case where the
      pointer is be fetch and not dereferenced.  This primitive may be
      used without protection, RCU or otherwise, due to the fact that
      it uses ACCESS_ONCE().
      
      The new rcu_dereference_protected() primitive is for the case
      where updates are prevented, for example, due to holding the
      update-side lock.  This primitive does neither ACCESS_ONCE() nor
      smp_read_barrier_depends(), so can only be used when updates are
      somehow prevented.
      Suggested-by: NDavid Howells <dhowells@redhat.com>
      Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: laijs@cn.fujitsu.com
      Cc: dipankar@in.ibm.com
      Cc: mathieu.desnoyers@polymtl.ca
      Cc: josh@joshtriplett.org
      Cc: dvhltc@us.ibm.com
      Cc: niv@us.ibm.com
      Cc: peterz@infradead.org
      Cc: rostedt@goodmis.org
      Cc: Valdis.Kletnieks@vt.edu
      Cc: dhowells@redhat.com
      Cc: eric.dumazet@gmail.com
      LKML-Reference: <1270852752-25278-1-git-send-email-paulmck@linux.vnet.ibm.com>
      Signed-off-by: NIngo Molnar <mingo@elte.hu>
      b62730ba
  14. 12 4月, 2010 1 次提交
    • T
      NFSv4: fix delegated locking · 0df5dd4a
      Trond Myklebust 提交于
      Arnaud Giersch reports that NFSv4 locking is broken when we hold a
      delegation since commit 8e469ebd (NFSv4:
      Don't allow posix locking against servers that don't support it).
      
      According to Arnaud, the lock succeeds the first time he opens the file
      (since we cannot do a delegated open) but then fails after we start using
      delegated opens.
      
      The following patch fixes it by ensuring that locking behaviour is
      governed by a per-filesystem capability flag that is initially set, but
      gets cleared if the server ever returns an OPEN without the
      NFS4_OPEN_RESULT_LOCKTYPE_POSIX flag being set.
      Reported-by: NArnaud Giersch <arnaud.giersch@iut-bm.univ-fcomte.fr>
      Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
      Cc: stable@kernel.org
      0df5dd4a
  15. 10 4月, 2010 4 次提交
  16. 09 4月, 2010 1 次提交
  17. 08 4月, 2010 1 次提交
  18. 07 4月, 2010 7 次提交
  19. 06 4月, 2010 2 次提交