Messages in this thread | | | Date | Sat, 5 Jun 2010 00:13:18 +1000 | From | Nick Piggin <> | Subject | Re: [patch 2/4] lglock: introduce special lglock and brlock spin locks |
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On Fri, Jun 04, 2010 at 09:56:03AM +0200, Eric Dumazet wrote: > Le vendredi 04 juin 2010 à 16:43 +1000, Nick Piggin a écrit : > > pièce jointe document texte brut (kernel-introduce-brlock.patch) > > This patch introduces "local-global" locks (lglocks). These can be used to: > > > > - Provide fast exclusive access to per-CPU data, with exclusive access to > > another CPU's data allowed but possibly subject to contention, and to provide > > very slow exclusive access to all per-CPU data. > > - Or to provide very fast and scalable read serialisation, and to provide > > very slow exclusive serialisation of data (not necessarily per-CPU data). > > > > Brlocks are also implemented as a short-hand notation for the latter use > > case. > > > > Thanks to Paul for local/global naming convention. > > > > Cc: linux-kernel@vger.kernel.org > > Cc: linux-fsdevel@vger.kernel.org > > Cc: Al Viro <viro@ZenIV.linux.org.uk> > > Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> > > Cc: Frank Mayhar <fmayhar@google.com>, > > Cc: John Stultz <johnstul@us.ibm.com> > > Cc: Andi Kleen <ak@linux.intel.com> > > Signed-off-by: Nick Piggin <npiggin@suse.de> > > --- > > include/linux/lglock.h | 165 +++++++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 165 insertions(+) > > > > IMHO some changes in Documentation/ would be needed
I wonder where, and what?
> > + void name##_global_lock(void) { \ > > + int i; \ > > + preempt_disable(); \ > > + rwlock_acquire(&name##_lock_dep_map, 0, 0, _RET_IP_); \ > > + for_each_online_cpu(i) { \ > > for_each_possible_cpu()
Oh good spotting. brlock does not need this but lglock does if it protects offline cpu data too. Maybe better to move file handles in the event of hotplug.
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