On Mon, Mar 26, 2012 at 7:02 PM, Blue Swirl <blauwir...@gmail.com> wrote: [...] > At least stack protector is protecting more code than before (for > example TLB miss handler), but could overhead from that amount to 5%? > > Otherwise there should be just a few extra register moves here and > there, that should be cheap on modern processors.
The extra moves might be cheap but their cost is obviously not 0: on top of using extra CPU core resources, code size is increased which results in more instruction cache misses. I didn't like the idea when we discussed it back in May, now it looks like we have concrete evidence the speed impact is measurable (though I'd like some more numbers than the rough 5% estimate I gave). Laurent
