Darrio Faggioli
2012-May-09 12:46 UTC
[PATCH v2] libxl: use xc_topologyinfo to figure out how many CPUs we actually have
Within libxl_get_cpu_topology(), considering all the CPUs the hypervisor
supports to be valid topology entries might lead to misleading and incorrect
behaviours, e.g., the output of `xl info -n'' below on a 16 cores
machine:
...
cpu_topology :
cpu: core socket node
0: 0 1 0
1: 0 1 0
2: 1 1 0
3: 1 1 0
4: 9 1 0
5: 9 1 0
6: 10 1 0
7: 10 1 0
8: 0 0 1
9: 0 0 1
10: 1 0 1
11: 1 0 1
12: 9 0 1
13: 9 0 1
14: 10 0 1
15: 10 0 1
16: 0 0 0
17: 0 0 0
18: 0 0 0
19: 0 0 0
20: 0 0 0
...
...
62: 0 0 0
63: 0 0 0
However, xc_topologyinfo() tells us (in max_cpu_index) how many entries
arrays it returns corresponds to actually valid CPUs, so let''s use that
information.
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -2895,6 +2895,9 @@ libxl_cputopology *libxl_get_cpu_topolog
goto fail;
}
+ if (tinfo.max_cpu_index < max_cpus - 1)
+ max_cpus = tinfo.max_cpu_index + 1;
+
ret = malloc(sizeof(libxl_cputopology) * max_cpus);
if (ret == NULL) {
LIBXL__LOG_ERRNOVAL(ctx, XTL_ERROR, ENOMEM,
Ian Jackson
2012-May-11 11:40 UTC
Re: [PATCH v2] libxl: use xc_topologyinfo to figure out how many CPUs we actually have
Darrio Faggioli writes ("[Xen-devel] [PATCH v2] libxl: use xc_topologyinfo
to figure out how many CPUs we actually have"):> Within libxl_get_cpu_topology(), considering all the CPUs the hypervisor
> supports to be valid topology entries might lead to misleading and
incorrect
> behaviours, e.g., the output of `xl info -n'' below on a 16 cores
machine:
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>