On Mon, 27 Aug 2007, Mathieu Desnoyers wrote: > * Christoph Lameter ([EMAIL PROTECTED]) wrote: > > On Mon, 27 Aug 2007, Peter Zijlstra wrote: > > > > > So, if the fast path can be done with a preempt off, it might be doable > > > to suffer the slow path with a per cpu lock like that. > > > > Sadly the cmpxchg_local requires local per cpu data access. Isnt there > > some way to make this less expensive on RT? Acessing cpu local memory is > > really good for performance on NUMA since the data is optimally placed and > > one can avoid/reduce locking if the process stays tied to the processor. > > > > On the slow path, in slab_new, we already have to reenable interrupts > because we can sleep. If we make sure that whenever we return to an irq > disable code path we take the current per-cpu data structure again, can > we make the preempt-disable/irq-disabled code paths O(1) ?
Not sure exactly what you are getting at? This would mean running __alloc_pages tied to one processor even though waiting is possible? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
