On Mon, Sep 21, 2015 at 09:36:15AM -0700, Linus Torvalds wrote: > On Mon, Sep 21, 2015 at 1:46 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote: > > > > Linus, what's your preference? > > So quite frankly, is there any reason we don't just implement > native_read_msr() as just > > unsigned long long native_read_msr(unsigned int msr) > { > int err; > unsigned long long val; > > val = native_read_msr_safe(msr, &err); > WARN_ON_ONCE(err); > return val; > } > > Note: no inline, no nothing. Just put it in arch/x86/lib/msr.c, and be > done with it. I don't see the downside. > > How many msr reads are <i>so</i> critical that the function call > overhead would matter? Get rid of the inline version of the _safe() > thing too, and put that thing there too. There are a few in the perf code, and esp. on cores without a stack engine the call overhead is noticeable. Also note that the perf MSRs are generally optimized MSRs and less slow (we cannot say fast, they're still MSRs) than regular MSRs. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html