On Tue, 26 Jun 2007 19:08:27 +0200 (CEST) Roman Zippel <[EMAIL PROTECTED]> wrote:
> > This current ... interesting piece of Roman about a _single_ trivial > > unlikely() branch in do_gettimeofday() borders on the ridiculous. My > > patch might be wrong for various reasons, but that single > > 'if (unlikely())' statement is not one of those reasons =B-) > > That's even more nonsense, that wasn't what my mail was about and Andrew > understood me correctly, so you could have too. umm, yeah. Ingo went a bit over the top there, IMO. It boils down to: is sys_time() called at more or less than 1/2000th the frequency of gettimeofday(), across the expected lifetime of 2.6.23 and later? Ingo has a couple of (surprising) examples where the sys_time() call frequency _is_ high, but whether that will remain true across 2.6.23 and later is an open question. How does mysql call sys_time() at all, if time(2) uses the vsyscall page?? Will contemporary-to-2.6.23-and-later mysqls do this? All this isn't super-trivial silliness, either. gettimeofday() is, for many workloads, the kernel's most time-critical codepath bar none, I believe. - 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/
