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Re: [Xen-devel] [PATCH] TSC scaling for live migration betweenplatforms

To: "Xiantao Zhang" <xiantao.zhang@xxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] TSC scaling for live migration betweenplatforms with different TSC frequecies
From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Date: Thu, 18 Jun 2009 08:37:58 +0100
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
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>>> "Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx> 18.06.09 04:56 >>>
>PATCH 0003-- Scaling host TSC freqeuncy patch. 

>+int hvm_gtsc_need_scale(struct domain *d)
>+{
>+    uint32_t gtsc_khz;
>+
>+    gtsc_khz = d->arch.hvm_domain.gtsc_khz / 1000;

Can the variable please be renamed to what it contains (i.e. gtsc_mhz)?

> u64 hvm_get_guest_tsc(struct vcpu *v)
> {
>-    u64 host_tsc;
>-
>-    if ( opt_softtsc )
>-        host_tsc = hvm_get_guest_time(v);
>-    else
>-        rdtscll(host_tsc);
>-
>-    return host_tsc + v->arch.hvm_vcpu.cache_tsc_offset;
>+    u64 host_tsc, scaled_htsc;
>+
>+    rdtscll(host_tsc);
>+    scaled_htsc = hvm_h2g_scale_tsc(v, host_tsc);
>+
>+    return scaled_htsc + v->arch.hvm_vcpu.cache_tsc_offset;
> }
> 
> void hvm_migrate_timers(struct vcpu *v)

I'm getting the impression that the opt_softtsc functionality got lost here.

>+        printk("Migrate to a platform with different freq:%ldMhz, "
>+            "expected freq:%dMhz, enable rdtsc exiting!\n",
>+                    cpu_khz / 1000, hdr->gtsc_khz / 1000);

gdprintk()? At least, I think, any guest related printk-s should identify which
guest they're about.

Jan


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