> > On Tue, Mar 17, 2015 at 01:45:25AM +0000, Mathieu Desnoyers wrote: [...] > > > > > Would you see it as acceptable if we start by implementing > > > only the non-expedited sys_membarrier() ? > > > > Sure. > > > > > Then we can add > > > the expedited-private implementation after rq->curr becomes > > > available through RCU. > > > > Yeah, or not at all; I'm still trying to get Paul to remove the > > expedited nonsense from the kernel RCU bits; and now you want it in > > userspace too :/ > > The non-expedited case makes sense when we batch RCU work > with call_rcu. However, some users require to use synchronize_rcu() > directly after modifying their data structure. Therefore, the > latency associated with sys_membarrier() then becomes important, > hence the interest for an expedited scheme. > > I agree that we should try to find a way to implement it with > low disturbance on the CPU's rq locks. I'd be certainly > OK with starting with just the non-expedited scheme, and add > the expedited scheme later on. This is why we have the flags > anyway.
Paul, I'm currently reworking the patch to keep only the non-expedited scheme. I don't need to touch the scheduler internals anymore, so should I move the sys_membarrier system call implementation into kernel/rcu/update.c ? Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
