Messages in this thread | | | Date | Mon, 17 Jun 2019 15:48:20 -0700 | From | Fenghua Yu <> | Subject | Re: [PATCH v4 3/5] x86/umwait: Add sysfs interface to control umwait C0.2 state |
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On Sun, Jun 09, 2019 at 09:26:29PM -0700, Andy Lutomirski wrote: > On Sun, Jun 9, 2019 at 9:14 PM Fenghua Yu <fenghua.yu@intel.com> wrote: > > > > On Sat, Jun 08, 2019 at 03:52:03PM -0700, Andy Lutomirski wrote: > > > On Fri, Jun 7, 2019 at 3:10 PM Fenghua Yu <fenghua.yu@intel.com> wrote: > > > > > > > > C0.2 state in umwait and tpause instructions can be enabled or disabled > > > > on a processor through IA32_UMWAIT_CONTROL MSR register. > > > > > > > > > > > +static u32 get_umwait_control_c02(void) > > > > +{ > > > > + return umwait_control_cached & MSR_IA32_UMWAIT_CONTROL_C02; > > > > +} > > > > + > > > > +static u32 get_umwait_control_max_time(void) > > > > +{ > > > > + return umwait_control_cached & MSR_IA32_UMWAIT_CONTROL_MAX_TIME; > > > > +} > > > > + > > > > > > I'm not convinced that these helpers make the code any more readable. > > > > The helpers reduce length of statements that call them. Otherwise, all of > > the statements would be easily over 80 characters. > > > > Plus, each of the helpers is called multiple places in #0003 and #0004. > > So the helpers make the patches smaller and cleaner. > > > > I was imagining things like: > > umwait_control_cached &= ~MSR_IA32_UMWAIT_CONTROL_C02; > if (whatever condition) > umwait_control_cached |= MSR_IA32_UMWAIT_CONTROL_C02; > umwait_control_cached &= ~MSR_IA32_UMWAIT_CONTROL_MAX_TIME; > umwait_control_cached |= new_max_time;
How about this statement? With the helpers: umwait_control_cached = max_time | get_umwait_control_c02(); If there is no helpers, the above statement will need two statements: umwait_control_cached &= ~MSR_IA32_UMWAIT_CONTROL_MAX_TIME; umwait_control_cached |= max_time;
Another example: With the helpers: if (umwait_control_c02 == get_umwait_control_c02()) If no helpers, the above statement will be long: if (umwait_control_c02 == (umwait_control_cached & MSR_IA32_UMWAIT_CONTROL_C02_DISABLED))
There are quite a few places like above examples.
The helpers can reduce the length of those long lines and make code more readable and shorter, right?
Can I still keep the helpers?
Thanks.
-Fenghua
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