Messages in this thread | | | Subject | Re: Perhaps a side effect regarding NMI returns | From | Steven Rostedt <> | Date | Tue, 29 Nov 2011 17:51:26 -0500 |
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On Tue, 2011-11-29 at 17:14 -0500, Jason Baron wrote: > On Tue, Nov 29, 2011 at 03:58:21PM -0500, Steven Rostedt wrote:
> > But people don't like the overhead that stop_machine() causes, and I > > have code that can make the modifications for ftrace with break points. > > By adding a break point, syncing, then modifying the code and break > > But if there's still has to be some sort of 'syncing' after we add a break > point, how much are we going to save? Or I guess your're using an IPI?
Well, anything is better than stop machine, event synchronize_sched() ;)
But the code I have in ftrace does bulk changes. It adds a break point to all functions, then it does the sync, then it updates all the points to the new code.
Looking at my code, here's what I did after setting up the breakpoints:
static void do_sync_core(void *data) { sync_core(); }
static void run_sync(void) { int enable_irqs = irqs_disabled();
/* We may be called with interrupts disbled. */ if (enable_irqs) local_irq_enable(); on_each_cpu(do_sync_core, NULL, 1); if (enable_irqs) local_irq_disable(); }
Note, it's fine to enable interrupts here, it's only used by ftrace.
-- Steve
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