Re: CVS commit: src/sys

[Mindaugas Rasiukevicius <rmind%netbsd.org@localhost>]

"Jukka Ruohonen" <jruoho%netbsd.org@localhost> wrote:
> Module Name:  src
> Committed By: jruoho
> Date:         Fri Feb 25 09:16:00 UTC 2011
> 
> Modified Files:
>       src/sys/arch/x86/acpi: acpi_cpu_md.c
>       src/sys/dev/acpi: acpi_cpu.h acpi_cpu_pstate.c
> 
> Log Message:
> Add preliminary support for the IA32_APERF and IA32_MPERF frequency
> counters. These are not yet used for anything and only Intel is supported
> at the moment.
> 
> ...

From acpicpu_md_pstate_percent():

> +     x86_disable_intr();
> +
> +     aperf = sc->sc_pstate_aperf;
> +     mperf = sc->sc_pstate_mperf;
> +
> +     xc = xc_unicast(0, acpicpu_md_pstate_percent_status, sc, NULL, ci);
> +     xc_wait(xc);
> +
> +     x86_enable_intr();

Why interrupts are disabled here?  Calling xc_wait() with interrupts
disabled is, at minimum, very expensive, and I would say it is wrong.
Note that xc_wait(9) does not necessary spin - it can block.

-- 
Mindaugas