Messages in this thread | | | Date | Thu, 20 Mar 2008 12:02:40 -0700 | From | Ravikiran G Thirumalai <> | Subject | Re: [patch 4/4] x86: apic_is_clustered_box to indicate unsynched TSC's on multiboard vSMP systems |
| |
On Thu, Mar 20, 2008 at 12:53:25AM -0700, Yinghai Lu wrote: >On Thu, Mar 20, 2008 at 12:45 AM, Ravikiran G Thirumalai ><kiran@scalex86.org> wrote: >> Indicate TSCs are unreliable as time sources if the platform is >> a multi chassi ScaleMP vSMPowered machine. >> >> Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org> >> >> Index: linux.git.trees/arch/x86/kernel/apic_64.c >> =================================================================== >> --- linux.git.trees.orig/arch/x86/kernel/apic_64.c 2008-03-19 20:42:28.187659497 -0700 >> +++ linux.git.trees/arch/x86/kernel/apic_64.c 2008-03-19 21:24:17.705515003 -0700 >> @@ -1208,7 +1208,7 @@ __cpuinit int apic_is_clustered_box(void >> * will be [4, 0x23] or [8, 0x27] could be thought to >> * vsmp box still need checking... >> */ >> - if (!is_vsmp_box() && (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)) >> + if ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) && !is_vsmp_box()) >> return 0; > >why? > >> >> bios_cpu_apicid = x86_bios_cpu_apicid_early_ptr; >> @@ -1248,6 +1248,12 @@ __cpuinit int apic_is_clustered_box(void >> ++zeros; >> } >> >> + /* ScaleMP vSMPowered boxes have one cluster per board and TSCs are >> + * not guaranteed to be synced between boards >> + */ >> + if (is_vsmp_box() && clusters > 1) >> + return 1; > >you still call that for intel box.
Yes. The first call is to state that TSC's are synced if it is an AMD box and if it is _not_ a vSMPowered box (for the apic id lifting case on Sun boxes), the second call is for _any_ vSMPowered system with more than one board -- TSC's are not guaranteed to be synched in that case. Both these calls are needed.
Thanks, Kiran
| |