Ping: Re: [PATCH v2] x86, vsmp: Remove is_vsmp_box() from apic_is_clustered_box()

From: Oren Twaig
Date: Sun Jul 13 2014 - 03:08:31 EST


ping
On 07/06/2014 09:33 AM, Oren Twaig wrote:
> Hi,
>
> Quick question: As I'm new at this (submitting patches), what is a reasonable
> time to wait before ping-ing a patch ?
>
> Oren.
>
> On 06/29/2014 01:01 PM, Oren Twaig wrote:
>> When a vSMP Foundation box is detected, the function apic_cluster_num() counts
>> the number of APIC clusters found. If more than one found, a multi board
>> configuration is assumed, and TSC marked as unstable. This behavior is
>> incorrect as vSMP Foundation may use processors from single node only, attached
>> to memory of other nodes - and such node may have more than one APIC cluster
>> (typically any recent intel box has more than single APIC_CLUSTERID(x)).
>>
>> To fix this, we simply remove the code which detects a vSMP Foundation box and
>> affects apic_is_clusted_box() return value. This can be done because later the
>> kernel checks by itself if the TSC is stable using the
>> check_tsc_sync_[source|target]() functions and marks TSC as unstable if needed.
>>
>> Acked-by: Shai Fultheim <shai@xxxxxxxxxxx>
>> Signed-off-by: Oren Twaig <oren@xxxxxxxxxxx>
>> ---
>> diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
>> index 19b0eba..c100694 100644
>> --- a/arch/x86/include/asm/apic.h
>> +++ b/arch/x86/include/asm/apic.h
>> @@ -85,14 +85,6 @@ static inline bool apic_from_smp_config(void)
>> #include <asm/paravirt.h>
>> #endif
>>
>> -#ifdef CONFIG_X86_64
>> -extern int is_vsmp_box(void);
>> -#else
>> -static inline int is_vsmp_box(void)
>> -{
>> - return 0;
>> -}
>> -#endif
>> extern int setup_profiling_timer(unsigned int);
>>
>> static inline void native_apic_mem_write(u32 reg, u32 v)
>> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
>> index ad28db7..2b85bb9 100644
>> --- a/arch/x86/kernel/apic/apic.c
>> +++ b/arch/x86/kernel/apic/apic.c
>> @@ -2451,51 +2451,6 @@ static void apic_pm_activate(void) { }
>>
>> #ifdef CONFIG_X86_64
>>
>> -static int apic_cluster_num(void)
>> -{
>> - int i, clusters, zeros;
>> - unsigned id;
>> - u16 *bios_cpu_apicid;
>> - DECLARE_BITMAP(clustermap, NUM_APIC_CLUSTERS);
>> -
>> - bios_cpu_apicid = early_per_cpu_ptr(x86_bios_cpu_apicid);
>> - bitmap_zero(clustermap, NUM_APIC_CLUSTERS);
>> -
>> - for (i = 0; i < nr_cpu_ids; i++) {
>> - /* are we being called early in kernel startup? */
>> - if (bios_cpu_apicid) {
>> - id = bios_cpu_apicid[i];
>> - } else if (i < nr_cpu_ids) {
>> - if (cpu_present(i))
>> - id = per_cpu(x86_bios_cpu_apicid, i);
>> - else
>> - continue;
>> - } else
>> - break;
>> -
>> - if (id != BAD_APICID)
>> - __set_bit(APIC_CLUSTERID(id), clustermap);
>> - }
>> -
>> - /* Problem: Partially populated chassis may not have CPUs in some of
>> - * the APIC clusters they have been allocated. Only present CPUs have
>> - * x86_bios_cpu_apicid entries, thus causing zeroes in the bitmap.
>> - * Since clusters are allocated sequentially, count zeros only if
>> - * they are bounded by ones.
>> - */
>> - clusters = 0;
>> - zeros = 0;
>> - for (i = 0; i < NUM_APIC_CLUSTERS; i++) {
>> - if (test_bit(i, clustermap)) {
>> - clusters += 1 + zeros;
>> - zeros = 0;
>> - } else
>> - ++zeros;
>> - }
>> -
>> - return clusters;
>> -}
>> -
>> static int multi_checked;
>> static int multi;
>>
>> @@ -2540,20 +2495,7 @@ static void dmi_check_multi(void)
>> int apic_is_clustered_box(void)
>> {
>> dmi_check_multi();
>> - if (multi)
>> - return 1;
>> -
>> - if (!is_vsmp_box())
>> - return 0;
>> -
>> - /*
>> - * ScaleMP vSMPowered boxes have one cluster per board and TSCs are
>> - * not guaranteed to be synced between boards
>> - */
>> - if (apic_cluster_num() > 1)
>> - return 1;
>> -
>> - return 0;
>> + return multi;
>> }
>> #endif
>>
>>
>
>


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