Messages in this thread | | | Date | Tue, 30 Nov 2010 15:03:20 -0600 (CST) | From | Christoph Lameter <> | Subject | Re: [thisops uV3 15/18] Xen: Use this_cpu_ops |
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On Tue, 30 Nov 2010, Jeremy Fitzhardinge wrote:
> On 11/30/2010 11:07 AM, Christoph Lameter wrote: > > static irqreturn_t xen_timer_interrupt(int irq, void *dev_id) > > { > > - struct clock_event_device *evt = &__get_cpu_var(xen_clock_events); > > irqreturn_t ret; > > > > ret = IRQ_NONE; > > - if (evt->event_handler) { > > - evt->event_handler(evt); > > + if (__this_cpu_read(xen_clock_events.event_handler)) { > > + __this_cpu_read(xen_clock_events.event_handler)(evt); > > Really? What code does this generate? If this is generating two > segment-prefixed reads rather than getting the address and doing normal > reads on it, then I don't think it is an improvement.
Lets drop that hunk. No point to do optimizations at that location then.
evt is also not defined then. Without the evt address determination via __get_cpu_var we have at least 2 prefixed load and one address calculation to figure out the parameter to pass. No win.
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