>-----Original Message----- >From: Andi Kleen [mailto:andi@xxxxxxxxxxxxxx] >Sent: Monday, July 06, 2009 4:44 PM >To: Vaidyanathan Srinivasan >Cc: Li, Shaohua; Peter Zijlstra; linux-acpi@xxxxxxxxxxxxxxx; >tglx@xxxxxxxxxxxxx; lenb@xxxxxxxxxx; Pallipadi, Venkatesh; >andi@xxxxxxxxxxxxxx; Ingo Molnar >Subject: Re: [PATCH]new ACPI processor driver to force CPUs idle > >On Mon, Jul 06, 2009 at 11:33:12PM +0530, Vaidyanathan >Srinivasan wrote: >> > > >> > > How do we handle interrupts and timers during this >interval? You seem >> > > to disable interrupts and hold the cpu at idle for 0.95 >sec. It may >> > > cause timeouts and overflows for network interrupts right? >> > The x86 mwait/monitor instruction can detect interrupt and >complete execution >> > even interrupt is disabled, so this isn't an issue. >> >> Cool, this will save a lot of trouble :) > >This is only available in newer Intel CPUs. > This is present in Intel Core/Core 2 and beyond. Shaohua's patch is checking for this in init path > > + if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) || > + !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) > + return; > and -EINVALing when the feature is not present. So, that will disable the feature on older CPUs. Thanks, Venki -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
