[Xen-devel] [PATCH] Allow get idle time stats by mask

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

More specifically, here is what I meant. Build tested.

Allow dom0 to request idle stats by mask, which is required
by sw coordination model. Also NOW() is stamped for caller
to cal sample period.

Signed-off-by Kevin Tian <kevin.tian@xxxxxxxxx>

diff -r 17f3e4f7bbe6 xen/arch/x86/platform_hypercall.c
--- a/xen/arch/x86/platform_hypercall.c Mon Oct 22 17:44:07 2007 -0400
+++ b/xen/arch/x86/platform_hypercall.c Tue Oct 23 16:53:43 2007 -0400
@@ -293,19 +293,23 @@ ret_t do_platform_op(XEN_GUEST_HANDLE(xe
 
     case XENPF_getidletime:
     {
-        uint32_t i, nr_cpus;
+        uint32_t i;
         uint64_t idletime;
         struct vcpu *v;
+        struct xenctl_cpumap ctlmap;
+        cpumask_t cpumap;
         XEN_GUEST_HANDLE(uint64_t) idletimes;
 
         ret = -ENOSYS;
         if ( cpufreq_controller != FREQCTL_dom0_kernel )
             break;
 
+        ctlmap.nr_cpus = op->u.getidletime.nr_cpus;
+        guest_from_compat_handle(ctlmap.bitmap, op->u.getidletime.bitmap);
+        xenctl_cpumap_to_cpumask(&cpumap, &ctlmap);
         guest_from_compat_handle(idletimes, op->u.getidletime.idletime);
-        nr_cpus = min_t(uint32_t, op->u.getidletime.max_cpus, NR_CPUS);
-
-        for ( i = 0; i < nr_cpus; i++ )
+
+        for_each_cpu_mask(i, cpumap)
         {
             /* Assume no holes in idle-vcpu map. */
             if ( (v = idle_vcpu[i]) == NULL )
@@ -318,9 +322,12 @@ ret_t do_platform_op(XEN_GUEST_HANDLE(xe
             ret = -EFAULT;
             if ( copy_to_guest_offset(idletimes, i, &idletime, 1) )
                 goto out;
-        }
-
-        op->u.getidletime.nr_cpus = i;
+
+            cpu_clear(i, cpumap);
+        }
+
+        op->u.getidletime.now = NOW();
+        cpumask_to_xenctl_cpumap(&ctlmap, &cpumap);
         ret = copy_to_guest(u_xenpf_op, op, 1) ? -EFAULT : 0;
     }
     break;
diff -r 17f3e4f7bbe6 xen/include/public/platform.h
--- a/xen/include/public/platform.h     Mon Oct 22 17:44:07 2007 -0400
+++ b/xen/include/public/platform.h     Tue Oct 23 16:12:22 2007 -0400
@@ -176,11 +176,12 @@ DEFINE_XEN_GUEST_HANDLE(xenpf_change_fre
 
 #define XENPF_getidletime         53
 struct xenpf_getidletime {
-    /* IN variables. */
-    uint32_t max_cpus;
+    /* IN variables */
+    XEN_GUEST_HANDLE(uint8_t) bitmap;
+    uint32_t nr_cpus;
     XEN_GUEST_HANDLE(uint64_t) idletime;
-    /* OUT variables. */
-    uint32_t nr_cpus;
+    /* OUT variables */
+    uint64_t now;
 };
 typedef struct xenpf_getidletime xenpf_getidletime_t;
 DEFINE_XEN_GUEST_HANDLE(xenpf_getidletime_t);

>From: Tian, Kevin
>Sent: 2007年10月24日 11:08
>To: Mark Langsdorf; xen-devel@xxxxxxxxxxxxxxxxxxx
>Subject: RE: [Xen-devel] [PATCH][cpufreq] Xen support for the
>ondemandgovernor [1/2] (hypervisor code)
>
>>From: Mark Langsdorf
>>Sent: 2007年10月24日 6:00
>>
>>Modify the cpufreq ondemand governor so that it can get idle and
>>total ticks from the Xen hypervisor.  Linux and Xen have different
>>ideas of what an idle tick is, so the Xen values for both have to
>>be returned in the same platform hypercall.
>>
>>Signed-off-by: Mark Langsdorf <mark.langsdorf@xxxxxxx>
>
>I would suggest adding bit mask info into getidletime, and then only
>fetching idle stats of concerned cpus. Currently [0-max_cpus] is
>overkill when on-demand governor only takes care of one cpu (hw
>coordination) or sibling cores (sw coordination).
>
>Also there's no need to return total time for each concerned cpu. For
>sw coordination model, on-demand governor only runs on one cpu
>and getidletime is only called on that agent cpu which takes care of
>all the rest idle stats. Naturally elapsed cycles since last sample point
>should be same on all affected cpus and it's useless to cal for them
>individually. You just need to stamp NOW() for the sample point.
>
>Thanks,
>Kevin
>
>_______________________________________________
>Xen-devel mailing list
>Xen-devel@xxxxxxxxxxxxxxxxxxx
>http://lists.xensource.com/xen-devel

Attachment: getidletime_mask.patch
Description: getidletime_mask.patch

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