[Xen-changelog] [xen stable-4.6] xen: Remove buggy initial placement algorithm

[patchbot@xxxxxxx]

commit 715242a2764570680c4f9f5b039e390a8a78a642
Author:     George Dunlap <george.dunlap@xxxxxxxxxx>
AuthorDate: Fri Aug 5 13:47:31 2016 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Aug 5 13:47:31 2016 +0200

    xen: Remove buggy initial placement algorithm
    
    The initial placement algorithm sometimes picks cpus outside of the
    mask it's given, does a lot of unnecessary bitmasking, does its own
    separate load calculation, and completely ignores vcpu hard and soft
    affinities.  Just get rid of it and rely on the schedulers to do
    initial placement.
    
    Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxx>
    Reviewed-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: d5438accceecc8172db2d37d98b695eb8bc43afc
    master date: 2016-07-26 10:44:06 +0100
---
 xen/common/domctl.c | 50 +-------------------------------------------------
 1 file changed, 1 insertion(+), 49 deletions(-)

diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index 7f959f3..efed3df 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -216,54 +216,6 @@ void getdomaininfo(struct domain *d, struct 
xen_domctl_getdomaininfo *info)
     memcpy(info->handle, d->handle, sizeof(xen_domain_handle_t));
 }
 
-static unsigned int default_vcpu0_location(cpumask_t *online)
-{
-    struct domain *d;
-    struct vcpu   *v;
-    unsigned int   i, cpu, nr_cpus, *cnt;
-    cpumask_t      cpu_exclude_map;
-
-    /* Do an initial CPU placement. Pick the least-populated CPU. */
-    nr_cpus = cpumask_last(&cpu_online_map) + 1;
-    cnt = xzalloc_array(unsigned int, nr_cpus);
-    if ( cnt )
-    {
-        rcu_read_lock(&domlist_read_lock);
-        for_each_domain ( d )
-            for_each_vcpu ( d, v )
-                if ( !test_bit(_VPF_down, &v->pause_flags)
-                     && ((cpu = v->processor) < nr_cpus) )
-                    cnt[cpu]++;
-        rcu_read_unlock(&domlist_read_lock);
-    }
-
-    /*
-     * If we're on a HT system, we only auto-allocate to a non-primary HT. We
-     * favour high numbered CPUs in the event of a tie.
-     */
-    cpumask_copy(&cpu_exclude_map, per_cpu(cpu_sibling_mask, 0));
-    cpu = cpumask_first(&cpu_exclude_map);
-    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_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));
-        if ( !cnt || cnt[i] <= cnt[cpu] )
-            cpu = i;
-    }
-
-    xfree(cnt);
-
-    return cpu;
-}
-
 bool_t domctl_lock_acquire(void)
 {
     /*
@@ -687,7 +639,7 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) 
u_domctl)
                 continue;
 
             cpu = (i == 0) ?
-                default_vcpu0_location(online) :
+                cpumask_any(online) :
                 cpumask_cycle(d->vcpu[i-1]->processor, online);
 
             if ( alloc_vcpu(d, i, cpu) == NULL )
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.6

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