From b4d3bc3dbbdf4c4a81b4bf16cf080404d20333b9 Mon Sep 17 00:00:00 2001 From: "iap10@freefall.cl.cam.ac.uk" Date: Thu, 31 Mar 2005 21:22:05 +0000 Subject: [PATCH] bitkeeper revision 1.1159.278.1 (424c69fdsFkm7FZ7SYMwK1Y6v6p1Og) Make default CPU placement of domains a bit smarter on systems with hyperthreading: only dom0 gets to use hyperthreading by default, we effectively ignore it on all other CPUs by allocating domains to the same hyperthread. If you don't like this, use 'xm pincpu' to change it. [note: we probably need to make pincpu more expressive, providing a list of CPUs that the domain can be scheduled on.] Signed-off-by: ian@xensource.com --- xen/common/dom0_ops.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/xen/common/dom0_ops.c b/xen/common/dom0_ops.c index e5b9f1d1e7..3af35e39e0 100644 --- a/xen/common/dom0_ops.c +++ b/xen/common/dom0_ops.c @@ -161,7 +161,7 @@ long do_dom0_op(dom0_op_t *u_dom0_op) case DOM0_CREATEDOMAIN: { struct domain *d; - unsigned int pro = 0; + unsigned int pro; domid_t dom; dom = op->u.createdomain.domain; @@ -178,16 +178,22 @@ long do_dom0_op(dom0_op_t *u_dom0_op) { /* Do an initial placement. Pick the least-populated CPU. */ struct domain *d; - unsigned int i, cnt[NR_CPUS] = { 0 }; + unsigned int i, ht, cnt[NR_CPUS] = { 0 }; read_lock(&domlist_lock); for_each_domain ( d ) cnt[d->processor]++; read_unlock(&domlist_lock); - for ( i = 0; i < smp_num_cpus; i++ ) - if ( cnt[i] < cnt[pro] ) - pro = i; + /* If we're on a HT system, we only use the first HT for dom0, + other domains will all share the second HT of each CPU. + Since dom0 is on CPU 0, we favour high numbered CPUs in + the event of a tie */ + ht = opt_noht ? 1 : ht_per_core; + pro = ht-1; + for ( i = pro; i < smp_num_cpus; i += ht ) + if ( cnt[i] <= cnt[pro] ) + pro = i; } else pro = op->u.createdomain.cpu % smp_num_cpus; -- 2.30.2