ping
On 06/23/2014 08:35 AM, Oren Twaig wrote:
> Remove invalid code which caused TSC to be declared as "unstable" on vSMP
> Foundation box even if it was stable and let the kernel decide for itself.
>
> 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.
>
> Signed-off-by: Oren Twaig
> Acked-by: Shai Fultheim
> ---
> arch/x86/include/asm/apic.h |8 --
> arch/x86/kernel/apic/apic.c | 60
> +--
> 2 files changed, 1 insertion(+), 67 deletions(-)
>
> 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
> #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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