[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] X86: Prefer TSC-deadline timer in Xen
At 14:54 +0100 on 28 Oct (1288277689), Wei, Gang wrote: > > From: Jan Beulich [mailto:JBeulich@xxxxxxxxxx], October 28, 2010 7:43 PM > > >>> On 28.10.10 at 11:48, "Wei, Gang" <gang.wei@xxxxxxxxx> wrote: > > >> From: Jan Beulich [mailto:JBeulich@xxxxxxxxxx], Thursday, October 28, > > 2010 > > > 3:46 PM > > >> >>> On 28.10.10 at 07:45, "Wei, Gang" <gang.wei@xxxxxxxxx> wrote: > > >> > --- a/xen/arch/x86/apic.c Wed Oct 20 17:26:51 2010 +0100 > > >> > +++ b/xen/arch/x86/apic.c Fri Oct 29 19:24:56 2010 +0800 > > >> > @@ -37,6 +37,15 @@ > > >> > #include <asm/asm_defns.h> /* for BUILD_SMP_INTERRUPT */ > > >> > #include <mach_apic.h> > > >> > #include <io_ports.h> > > >> > + > > >> > +#define APIC_TIMER_MODE_ONESHOT (0 << 17) > > >> > +#define APIC_TIMER_MODE_PERIODIC (1 << 17) > > >> > +#define APIC_TIMER_MODE_TSC_DEADLINE (2 << 17) > > >> > +#define APIC_TIMER_MODE_MASK (3 << 17) > > >> > + > > >> > +static int tdt_enabled; > > >> > +static int tdt_disable; > > >> > +boolean_param("tdt_off", tdt_disable); > > >> > > >> It would be more natural to call the parameter just "tdt", and > > >> use a non-zero initialized variable that gets set to zero when > > >> the user passes "tdt=off" (or another of the boolean false > > >> indicators). Perhaps you could even get away with just the > > >> single "tdt_enabled" variable then. > > > > > > Rename the parameter should be ok. But I prefer to keep two variable there > > > to avoid check both tdt_enabled & > > boot_cpu_has(X86_FEATURE_TSC_DEADLINE) > > > everywhere. > > > > Why? Just clear tdt_enabled when you find > > !boot_cpu_has(X86_FEATURE_TSC_DEADLINE) during initialization. > > > > And btw., this (or if you really want to keep them separate, both) > > variable(s) are pretty reasonable candidates for __read_mostly. > > I still want to keep them because __setup_APIC_LVTT() will be called > multiple times - the first call with tdt_enabled == false, and the > following calls with tdt_enabled == true. Is that important? If so, please add explanatory comments in the appropriate places, because it's not obvious that it's happening, or why. Tim. -- Tim Deegan <Tim.Deegan@xxxxxxxxxx> Principal Software Engineer, XenServer Engineering Citrix Systems UK Ltd. (Company #02937203, SL9 0BG) _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |