Re: [PATCH 1/4] ACPI: Add acpi_pr_() interfaces

Toshi Kani
2012-07-24T16:13:08Z

On Tue, 2012-07-24 at 09:55 -0600, Toshi Kani wrote:
> On Thu, 2012-07-19 at 17:43 -0600, Toshi Kani wrote:
> > On Thu, 2012-07-19 at 16:32 -0600, Shuah Khan wrote:
> > > On Thu, 2012-07-19 at 14:51 -0600, Toshi Kani wrote:
> > >
> > > > If your concern is actually a performance bottleneck in acpi_get_name()
> > > > you found in the code, you should report it to the ACPI CA team.
> > >
> > > I have tried my best to get you to understand the problems in bigger
> > > picture your patch set can exacerbate. Looking to somebody else to fix
> > > the problems doesn't help. It doesn't look like we can come to an
> > > agreement here, we just have to agree to disagree.
> >
> > I am not asking someone to fix it. I tried my best to explain that
> > acpi_get_name() does not lead any performance issue when it is called in
> > the error paths of ACPI drivers, and why we have to call it to obtain an
> > object path info for error analysis. If you still believe there is a
> > performance issue in calling acpi_get_name() under this context, please
> > help us understand where the performance bottleneck is in the code. (I
> > hope you just concerned it because it has "acpi_" prefix...) I will then
> > work on the issue with the ACPI CA team.
>
> I have measured acpi_pr_<level>() to make sure my statement is correct.
> Here are the results:
>
> Avg. acpi_get_name() 587 ns
> Avg. printk() 3420 ns
> Avg. kfree() 238 ns
> Avg. acpi_get_time()+kfree() 825 ns
>
> The results indicate that acpi_pr_<level>() has 20% increase of the time

Oops, I should have stated that it is 24% increase to printk(), or 20%
of time in acpi_pr_<level>().

-Toshi

> compared to the regular printk(), which is less than 1 us. I believe
> the results endorse my statement, and may not cause any performance
> issue to the error paths of the ACPI drivers.
>
> -Toshi
>
>
> > Thanks,
> > -Toshi
> >
> >
> >
> > > caio,
> > > -- Shuah
> > >
> >
>