On Thu 2016-10-27 10:28:01, Peter Zijlstra wrote: > On Wed, Oct 26, 2016 at 10:54:16PM +0200, Pavel Machek wrote: > > Hi! > > > > I'd like to get an interrupt every million cache misses... to do a > > printk() or something like that. As far as I can tell, modern hardware > > should allow me to do that. AFAICT performance events subsystem can do > > something like that, but I can't figure out where the code is / what I > > should call. > > > > Can someone help? > > Can you go back one step and explain why you would want this? What use > is a printk() on every 1e6-th cache miss. > > That is, why doesn't: > > $ perf record -e cache-misses -c 1000000 -a -- sleep 5 > > suffice?
How to work around rowhammer, break my system _and_ make kernel perf
maintainers scream at the same time: (:-) )
I think I got the place now. Let me try...
Thanks,
Pavel
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index d31735f..ce83f5e 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1495,6 +1495,11 @@ perf_event_nmi_handler(unsigned int cmd, struct pt_regs
*regs)
perf_sample_event_took(finish_clock - start_clock);
+ /* Here */
+ {
+ udelay(58000);
+ }
+
return ret;
}
NOKPROBE_SYMBOL(perf_event_nmi_handler);
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
signature.asc
Description: Digital signature
