From: Jan Beulich <jbeulich@suse.com>
Date: Fri, 23 Aug 2013 13:07:00 +0000 (+0200)
Subject: domctl: replace cpumask_weight() uses
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~6463
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=30e9a840b822ea57319abc0d136945a150fb915b;p=xen.git

domctl: replace cpumask_weight() uses

In one case it could easily be replaced by range checking the result of
a subsequent operation, and in general cpumask_next(), not always
needing to scan the whole bitmap, is more efficient than the specific
uses of cpumask_weight() here. (When running on big systems, operations
on CPU masks aren't cheap enough to use them carelessly.)

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>
---

diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index c653efb74b..9760d50955 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -230,15 +230,15 @@ static unsigned int default_vcpu0_location(cpumask_t *online)
      */
     cpumask_copy(&cpu_exclude_map, per_cpu(cpu_sibling_mask, 0));
     cpu = cpumask_first(&cpu_exclude_map);
-    if ( cpumask_weight(&cpu_exclude_map) > 1 )
-        cpu = cpumask_next(cpu, &cpu_exclude_map);
-    ASSERT(cpu < nr_cpu_ids);
+    i = cpumask_next(cpu, &cpu_exclude_map);
+    if ( i < nr_cpu_ids )
+        cpu = i;
     for_each_cpu(i, online)
     {
         if ( cpumask_test_cpu(i, &cpu_exclude_map) )
             continue;
         if ( (i == cpumask_first(per_cpu(cpu_sibling_mask, i))) &&
-             (cpumask_weight(per_cpu(cpu_sibling_mask, i)) > 1) )
+             (cpumask_next(i, per_cpu(cpu_sibling_mask, i)) < nr_cpu_ids) )
             continue;
         cpumask_or(&cpu_exclude_map, &cpu_exclude_map,
                    per_cpu(cpu_sibling_mask, i));