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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v10 10/11] libxl/xl: make it possible to specify soft-affinity in domain config file
To do so, we add the vcpu_soft_affinity array to build_info, and
treat it much like vcpu_hard_affinity. The new config option is
called "cpus_soft".
Note that the vcpu_hard_affinity array, introduced in a previous
patch, and the vcpu_soft_affinity array, introduced here, share
the same LIBXL_HAVE_xxx macro, in libxl.h. That is called
LIBXL_HAVE_BUILDINFO_VCPU_AFFINITY_ARRAYS, and was introduced
together with vcpu_hard_affinity, but only inside a comment.
In this change, we uncomment, and hence properly define it.
Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
---
Changes from v9:
* patch reworked again, due to changes in the preceding ones
in the series. The structure is similar, it's still based
on adding some indirection, so that the same code can be
used to pars and enact both hard and soft affinity, but
the code did change, I'm afraid.
Changes from v8:
* fix a type in the LIBXL_HAVE_xxx macro name.
Changes from v7:
* WARNING: this patch underwent quite a fundamental rework,
given it's now building on top of Wei's "push vcpu affinity
to libxl" patch. That's why I think it should be re-reviewed
almost from scratch (sorry! :-P), and that's why I did not
add IanC's ack, although he provided it to the v7 version
of it.
Changes from v6:
* update and improve the changelog.
Changes from v4:
* fix typos and rephrase docs, as suggested during review;
* more refactoring, i.e., more addressing factor of potential
common code, as requested during review.
Changes from v3:
* fix typos and language issues in docs and comments, as
suggested during review;
* common code to soft and hard affinity parsing factored
together, as requested uring review.
Changes from v2:
* use the new libxl API. Although the implementation changed
only a little bit, I removed IanJ's Acked-by, although I am
here saying that he did provided it, as requested.
---
docs/man/xl.cfg.pod.5 | 23 ++++++++++++++++++++---
tools/libxl/libxl.h | 3 +--
tools/libxl/libxl_dom.c | 31 +++++++++++++++++++++++++------
tools/libxl/libxl_types.idl | 1 +
tools/libxl/xl_cmdimpl.c | 39 ++++++++++++++++++++++++++++++---------
5 files changed, 77 insertions(+), 20 deletions(-)
diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index af48622..25a4ff7 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -152,19 +152,36 @@ run on cpus 3,4,6,7,8 of the host.
=back
If this option is not specified, no vcpu to cpu pinning is established,
-and the vcpus of the guest can run on all the cpus of the host.
+and the vcpus of the guest can run on all the cpus of the host. If this
+option is specified, the intersection of the vcpu pinning mask, provided
+here, and the soft affinity mask, provided via B<cpus\_soft=> (if any),
+is utilized to compute the domain node-affinity, for driving memory
+allocations.
If we are on a NUMA machine (i.e., if the host has more than one NUMA
node) and this option is not specified, libxl automatically tries to
place the guest on the least possible number of nodes. That, however,
will not affect vcpu pinning, so the guest will still be able to run on
-all the cpus, it will just prefer the ones from the node it has been
-placed on. A heuristic approach is used for choosing the best node (or
+all the cpus. A heuristic approach is used for choosing the best node (or
set of nodes), with the goals of maximizing performance for the guest
and, at the same time, achieving efficient utilization of host cpus
and memory. See F<docs/misc/xl-numa-placement.markdown> for more
details.
+=item B<cpus_soft="CPU-LIST">
+
+Exactly as B<cpus=>, but specifies soft affinity, rather than pinning
+(hard affinity). When using the credit scheduler, this means what cpus
+the vcpus of the domain prefer.
+
+A C<CPU-LIST> is specified exactly as above, for B<cpus=>.
+
+If this option is not specified, the vcpus of the guest will not have
+any preference regarding on what cpu to run. If this option is specified,
+the intersection of the soft affinity mask, provided here, and the vcpu
+pinning, provided via B<cpus=> (if any), is utilized to compute the
+domain node-affinity, for driving memory allocations.
+
=back
=head3 CPU Scheduling
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index d63cd11..e0720f1 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -361,8 +361,7 @@ typedef struct libxl__ctx libxl_ctx;
* Each bitmap should be big enough to accommodate the maximum number of
* PCPUs of the host.
*/
-/* to be uncommented when soft array added */
-/* #define LIBXL_HAVE_BUILDINFO_VCPU_AFFINITY_ARRAYS 1 */
+#define LIBXL_HAVE_BUILDINFO_VCPU_AFFINITY_ARRAYS 1
/*
* LIBXL_HAVE_BUILDINFO_USBDEVICE_LIST
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index 81e77c0..076573a 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -272,18 +272,37 @@ int libxl__build_pre(libxl__gc *gc, uint32_t domid,
if (info->nodemap.size)
libxl_domain_set_nodeaffinity(ctx, domid, &info->nodemap);
/* As mentioned in libxl.h, vcpu_hard_array takes precedence */
- if (info->num_vcpu_hard_affinity) {
- int i;
+ if (info->num_vcpu_hard_affinity || info->num_vcpu_soft_affinity) {
+ libxl_bitmap *hard_affinity, *soft_affinity;
+ int i, n_vcpus;
+
+ n_vcpus = info->num_vcpu_hard_affinity > info->num_vcpu_soft_affinity ?
+ info->num_vcpu_hard_affinity : info->num_vcpu_soft_affinity;
+
+ for (i = 0; i < n_vcpus; i++) {
+ /*
+ * Prepare hard and soft affinity pointers in a way that allows
+ * us to issue only one call to libxl_set_vcpuaffinity(), setting,
+ * for each vcpu, both hard and soft affinity "atomically".
+ */
+ hard_affinity = NULL;
+ if (info->num_vcpu_hard_affinity &&
+ i < info->num_vcpu_hard_affinity)
+ hard_affinity = &info->vcpu_hard_affinity[i];
+
+ soft_affinity = NULL;
+ if (info->num_vcpu_soft_affinity &&
+ i < info->num_vcpu_soft_affinity)
+ soft_affinity = &info->vcpu_soft_affinity[i];
- for (i = 0; i < info->num_vcpu_hard_affinity; i++) {
if (libxl_set_vcpuaffinity(ctx, domid, i,
- &info->vcpu_hard_affinity[i],
- NULL)) {
+ hard_affinity, soft_affinity)) {
LOG(ERROR, "setting affinity failed on vcpu `%d'", i);
return ERROR_FAIL;
}
}
- } else if (info->cpumap.size) {
+ }
+ if (info->cpumap.size && !info->num_vcpu_hard_affinity) {
/*
* Although info->cpumap is DEPRECATED, we still want old
* applications that may be using it to continue working.
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 477b2a6..18355d9 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -310,6 +310,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
# will prevail.
("nodemap", libxl_bitmap),
("vcpu_hard_affinity", Array(libxl_bitmap, "num_vcpu_hard_affinity")),
+ ("vcpu_soft_affinity", Array(libxl_bitmap, "num_vcpu_soft_affinity")),
("numa_placement", libxl_defbool),
("tsc_mode", libxl_tsc_mode),
("max_memkb", MemKB),
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 8c94745..462da05 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -694,9 +694,10 @@ static void parse_top_level_sdl_options(XLU_Config *config,
static void parse_vcpu_affinity(XLU_Config *config, XLU_ConfigList *cpus,
libxl_domain_build_info *b_info,
- const char *buf, int num_cpus)
+ const char *buf, int num_cpus, bool is_hard)
{
- const char *buf2 = NULL; //XXX Trick the compiler!!!
+ const char *buf2 = NULL; /* initialize to trick gcc >= 4.9.0. See below */
+ libxl_bitmap *vcpu_affinity_array;
int j = 0;
/*
@@ -714,24 +715,37 @@ static void parse_vcpu_affinity(XLU_Config *config,
XLU_ConfigList *cpus,
if (num_cpus > b_info->max_vcpus || buf)
num_cpus = b_info->max_vcpus;
- b_info->vcpu_hard_affinity = xmalloc(num_cpus * sizeof(libxl_bitmap));
+ if (is_hard) {
+ b_info->num_vcpu_hard_affinity = num_cpus;
+ b_info->vcpu_hard_affinity = xmalloc(num_cpus * sizeof(libxl_bitmap));
+ vcpu_affinity_array = b_info->vcpu_hard_affinity;
+ } else {
+ b_info->num_vcpu_soft_affinity = num_cpus;
+ b_info->vcpu_soft_affinity = xmalloc(num_cpus * sizeof(libxl_bitmap));
+ vcpu_affinity_array = b_info->vcpu_soft_affinity;
+ }
while ((buf || (buf2 = xlu_cfg_get_listitem(cpus, j)) != NULL) &&
j < num_cpus) {
- libxl_bitmap_init(&b_info->vcpu_hard_affinity[j]);
- if (libxl_cpu_bitmap_alloc(ctx,
- &b_info->vcpu_hard_affinity[j], 0)) {
+ libxl_bitmap_init(&vcpu_affinity_array[j]);
+ if (libxl_cpu_bitmap_alloc(ctx, &vcpu_affinity_array[j], 0)) {
fprintf(stderr, "Unable to allocate cpumap for vcpu %d\n", j);
exit(1);
}
- if (vcpupin_parse(buf ? buf : buf2, &b_info->vcpu_hard_affinity[j]))
+ /*
+ * If buf2 is not initialized above, gcc >= 4.9.0 complains with
+ * a '[-Werror=maybe-uninitialized]'. That can't happen, though, since
+ * we use buf2 only if buf is NULL, and if we are here and buf is NULL,
+ * it means buf2 is non-NULL, and contains the j-eth element of the
+ * list, as per the condition of the while().
+ * */
+ if (vcpupin_parse(buf ? buf : buf2, &vcpu_affinity_array[j]))
exit(1);
j++;
}
- b_info->num_vcpu_hard_affinity = num_cpus;
/* We have a list of cpumaps, disable automatic placement */
libxl_defbool_set(&b_info->numa_placement, false);
@@ -847,7 +861,14 @@ static void parse_config_data(const char *config_source,
buf = NULL; num_cpus = 0;
if (!xlu_cfg_get_list (config, "cpus", &cpus, &num_cpus, 1) ||
!xlu_cfg_get_string (config, "cpus", &buf, 0))
- parse_vcpu_affinity(config, cpus, b_info, buf, num_cpus);
+ parse_vcpu_affinity(config, cpus, b_info, buf,
+ num_cpus, /* is_hard */ true);
+
+ buf = NULL; num_cpus = 0;
+ if (!xlu_cfg_get_list (config, "cpus_soft", &cpus, &num_cpus, 1) ||
+ !xlu_cfg_get_string (config, "cpus_soft", &buf, 0))
+ parse_vcpu_affinity(config, cpus, b_info, buf,
+ num_cpus, /* is_hard */ false);
if (!xlu_cfg_get_long (config, "memory", &l, 0)) {
b_info->max_memkb = l * 1024;
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