RE: [Xen-ia64-devel] [PATCH] fixes DOM0_PHYSINFO hypercall

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Masaki Kanno
>Sent: 2005年12月12日 18:52
>Hi,
>
>This patch fixes DOM0_PHYSINFO hypercall.
>
>However, I found a problem in 'smp_num_siblings'.
>I changed the setting of BIOS to disabled the hyperthread, so I expected
>'smp_num_siblings' to 1.
>But, its value is 2, because the value of log_overview.tpc
>(PAL_LOGICAL_TO_PHYSICAL) is 2.
>Is there any way to know the current setting of the hyperthread?

Hi, Kanno

        That depends on what you wanna that field to be. Current code from 
Linux just uses smp_num_siblings and smp_num_cpu_cores to record physical die 
information, which is retrieved from PAL_LOGICAL_TO_PHYSICAL in boot time. So 
they're exactly same meaning to threads_per_core and cores_per_socket here, 
which stands for static physical capability. That will not be affected by your 
BIOS setting.

        If you want to add a field to indicate active siblings of current 
logical processor (no such field in current phys_info), you should either go to 
cpuinfo_ia64 structure for field num_log which indicating online physical 
threads within this die. More specifically, you can even walk 
cpu_core_map(index) and cpu_sibling_map(index) for more detail online 
information. But it seems num_log should be enough.

        Hope helps.

Thanks,
Kevin
>
>Signed-off-by: Masaki Kanno <kanno.masaki@xxxxxxxxxxxxxx>
>
>Best Regards,
> Kan
>
>
>diff -r 0255f48b757f xen/arch/ia64/xen/dom0_ops.c
>--- a/xen/arch/ia64/xen/dom0_ops.c      Sun Dec  4 19:12:00 2005
>+++ b/xen/arch/ia64/xen/dom0_ops.c      Fri Dec  9 23:49:11 2005
>@@ -200,13 +200,13 @@
>         dom0_physinfo_t *pi = &op->u.physinfo;
>
>         pi->threads_per_core = smp_num_siblings;
>-        pi->cores_per_socket = 1; // FIXME
>+        pi->cores_per_socket = smp_num_cpucores;
>         pi->sockets_per_node =
>             num_online_cpus() / (pi->threads_per_core * pi->cores_per_socket);
>         pi->nr_nodes         = 1;
>         pi->total_pages      = 99;  // FIXME
>         pi->free_pages       = avail_domheap_pages();
>-        pi->cpu_khz          = 100;  // FIXME cpu_khz;
>+        pi->cpu_khz          = local_cpu_data->proc_freq / 1000;
>         memset(pi->hw_cap, 0, sizeof(pi->hw_cap));
>         //memcpy(pi->hw_cap, boot_cpu_data.x86_capability, NCAPINTS*4);
>         ret = 0;
>diff -r 0255f48b757f xen/include/asm-ia64/config.h
>--- a/xen/include/asm-ia64/config.h     Sun Dec  4 19:12:00 2005
>+++ b/xen/include/asm-ia64/config.h     Wed Dec  7 19:48:44 2005
>@@ -129,8 +129,10 @@
> // needed for common/dom0_ops.c until hyperthreading is supported
> #ifdef CONFIG_SMP
> extern int smp_num_siblings;
>+extern int smp_num_cpucores;
> #else
> #define smp_num_siblings 1
>+#define smp_num_cpucores 1
> #endif
>
> // from linux/include/linux/mm.h
>
>
>
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