| Message ID | 20221028095225.86118-6-david@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [GIT,PULL,1/8] hw/mem/nvdimm: fix error message for 'unarmed' flag | expand |
Hi,
turning pages back in time,
noticed that in recent qemu-img binaries we include an ELF dependency on libnuma.so that seems unused.
I think it stems from this commit:
commit 10218ae6d006f76410804cc4dc690085b3d008b5
Author: David Hildenbrand <david@redhat.com>
Date: Fri Oct 14 15:47:17 2022 +0200
util: Add write-only "node-affinity" property for ThreadContext
possibly this hunk?
diff --git a/util/meson.build b/util/meson.build
index e97cd2d779..c0a7bc54d4 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -1,5 +1,5 @@
util_ss.add(files('osdep.c', 'cutils.c', 'unicode.c', 'qemu-timer-common.c'))
-util_ss.add(files('thread-context.c'))
+util_ss.add(files('thread-context.c'), numa)
if not config_host_data.get('CONFIG_ATOMIC64')
util_ss.add(files('atomic64.c'))
endif
I wonder if there is some conditional we could use to avoid the apparently useless dependency to libnuma in the qemu-img binary?
Ciao,
Claudio
On 10/28/22 11:52, David Hildenbrand wrote:
> Let's make it easier to pin threads created via a ThreadContext to
> all host CPUs currently belonging to a given set of host NUMA nodes --
> which is the common case.
>
> "node-affinity" is simply a shortcut for setting "cpu-affinity" manually
> to the list of host CPUs belonging to the set of host nodes. This property
> can only be written.
>
> A simple QEMU example to set the CPU affinity to host node 1 on a system
> with two nodes, 24 CPUs each, whereby odd-numbered host CPUs belong to
> host node 1:
> qemu-system-x86_64 -S \
> -object thread-context,id=tc1,node-affinity=1
>
> And we can query the cpu-affinity via HMP/QMP:
> (qemu) qom-get tc1 cpu-affinity
> [
> 1,
> 3,
> 5,
> 7,
> 9,
> 11,
> 13,
> 15,
> 17,
> 19,
> 21,
> 23,
> 25,
> 27,
> 29,
> 31,
> 33,
> 35,
> 37,
> 39,
> 41,
> 43,
> 45,
> 47
> ]
>
> We cannot query the node-affinity:
> (qemu) qom-get tc1 node-affinity
> Error: Insufficient permission to perform this operation
>
> But note that due to dynamic library loading this example will not work
> before we actually make use of thread_context_create_thread() in QEMU
> code, because the type will otherwise not get registered. We'll wire
> this up next to make it work.
>
> Note that if the host CPUs for a host node change due do CPU hot(un)plug
> CPU onlining/offlining (i.e., lscpu output changes) after the ThreadContext
> was started, the CPU affinity will not get updated.
>
> Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
> Acked-by: Markus Armbruster <armbru@redhat.com>
> Message-Id: <20221014134720.168738-5-david@redhat.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
> qapi/qom.json | 9 ++++-
> util/meson.build | 2 +-
> util/thread-context.c | 84 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 93 insertions(+), 2 deletions(-)
>
> diff --git a/qapi/qom.json b/qapi/qom.json
> index 8013ba4b82..20b5735d78 100644
> --- a/qapi/qom.json
> +++ b/qapi/qom.json
> @@ -839,10 +839,17 @@
> # threads created in the thread context (default: QEMU main
> # thread CPU affinity)
> #
> +# @node-affinity: the list of host node numbers that will be resolved to a
> +# list of host CPU numbers used as CPU affinity. This is a
> +# shortcut for specifying the list of host CPU numbers
> +# belonging to the host nodes manually by setting
> +# @cpu-affinity. (default: QEMU main thread affinity)
> +#
> # Since: 7.2
> ##
> { 'struct': 'ThreadContextProperties',
> - 'data': { '*cpu-affinity': ['uint16'] } }
> + 'data': { '*cpu-affinity': ['uint16'],
> + '*node-affinity': ['uint16'] } }
>
>
> ##
> diff --git a/util/meson.build b/util/meson.build
> index e97cd2d779..c0a7bc54d4 100644
> --- a/util/meson.build
> +++ b/util/meson.build
> @@ -1,5 +1,5 @@
> util_ss.add(files('osdep.c', 'cutils.c', 'unicode.c', 'qemu-timer-common.c'))
> -util_ss.add(files('thread-context.c'))
> +util_ss.add(files('thread-context.c'), numa)
> if not config_host_data.get('CONFIG_ATOMIC64')
> util_ss.add(files('atomic64.c'))
> endif
> diff --git a/util/thread-context.c b/util/thread-context.c
> index c921905396..4138245332 100644
> --- a/util/thread-context.c
> +++ b/util/thread-context.c
> @@ -21,6 +21,10 @@
> #include "qemu/module.h"
> #include "qemu/bitmap.h"
>
> +#ifdef CONFIG_NUMA
> +#include <numa.h>
> +#endif
> +
> enum {
> TC_CMD_NONE = 0,
> TC_CMD_STOP,
> @@ -88,6 +92,11 @@ static void thread_context_set_cpu_affinity(Object *obj, Visitor *v,
> int nbits = 0, ret;
> Error *err = NULL;
>
> + if (tc->init_cpu_bitmap) {
> + error_setg(errp, "Mixing CPU and node affinity not supported");
> + return;
> + }
> +
> visit_type_uint16List(v, name, &host_cpus, &err);
> if (err) {
> error_propagate(errp, err);
> @@ -159,6 +168,79 @@ static void thread_context_get_cpu_affinity(Object *obj, Visitor *v,
> qapi_free_uint16List(host_cpus);
> }
>
> +static void thread_context_set_node_affinity(Object *obj, Visitor *v,
> + const char *name, void *opaque,
> + Error **errp)
> +{
> +#ifdef CONFIG_NUMA
> + const int nbits = numa_num_possible_cpus();
> + ThreadContext *tc = THREAD_CONTEXT(obj);
> + uint16List *l, *host_nodes = NULL;
> + unsigned long *bitmap = NULL;
> + struct bitmask *tmp_cpus;
> + Error *err = NULL;
> + int ret, i;
> +
> + if (tc->init_cpu_bitmap) {
> + error_setg(errp, "Mixing CPU and node affinity not supported");
> + return;
> + }
> +
> + visit_type_uint16List(v, name, &host_nodes, &err);
> + if (err) {
> + error_propagate(errp, err);
> + return;
> + }
> +
> + if (!host_nodes) {
> + error_setg(errp, "Node list is empty");
> + goto out;
> + }
> +
> + bitmap = bitmap_new(nbits);
> + tmp_cpus = numa_allocate_cpumask();
> + for (l = host_nodes; l; l = l->next) {
> + numa_bitmask_clearall(tmp_cpus);
> + ret = numa_node_to_cpus(l->value, tmp_cpus);
> + if (ret) {
> + /* We ignore any errors, such as impossible nodes. */
> + continue;
> + }
> + for (i = 0; i < nbits; i++) {
> + if (numa_bitmask_isbitset(tmp_cpus, i)) {
> + set_bit(i, bitmap);
> + }
> + }
> + }
> + numa_free_cpumask(tmp_cpus);
> +
> + if (bitmap_empty(bitmap, nbits)) {
> + error_setg(errp, "The nodes select no CPUs");
> + goto out;
> + }
> +
> + if (tc->thread_id != -1) {
> + /*
> + * Note: we won't be adjusting the affinity of any thread that is still
> + * around for now, but only the affinity of the context thread.
> + */
> + ret = qemu_thread_set_affinity(&tc->thread, bitmap, nbits);
> + if (ret) {
> + error_setg(errp, "Setting CPU affinity failed: %s", strerror(ret));
> + }
> + } else {
> + tc->init_cpu_bitmap = bitmap;
> + bitmap = NULL;
> + tc->init_cpu_nbits = nbits;
> + }
> +out:
> + g_free(bitmap);
> + qapi_free_uint16List(host_nodes);
> +#else
> + error_setg(errp, "NUMA node affinity is not supported by this QEMU");
> +#endif
> +}
> +
> static void thread_context_get_thread_id(Object *obj, Visitor *v,
> const char *name, void *opaque,
> Error **errp)
> @@ -208,6 +290,8 @@ static void thread_context_class_init(ObjectClass *oc, void *data)
> object_class_property_add(oc, "cpu-affinity", "int",
> thread_context_get_cpu_affinity,
> thread_context_set_cpu_affinity, NULL, NULL);
> + object_class_property_add(oc, "node-affinity", "int", NULL,
> + thread_context_set_node_affinity, NULL, NULL);
> }
>
> static void thread_context_instance_init(Object *obj)
On 05.02.24 11:14, Claudio Fontana wrote: > Hi, Hi Claudio, > > turning pages back in time, > > noticed that in recent qemu-img binaries we include an ELF dependency on libnuma.so that seems unused. > > I think it stems from this commit: > > commit 10218ae6d006f76410804cc4dc690085b3d008b5 > Author: David Hildenbrand <david@redhat.com> > Date: Fri Oct 14 15:47:17 2022 +0200 > > util: Add write-only "node-affinity" property for ThreadContext > > > possibly this hunk? > > diff --git a/util/meson.build b/util/meson.build > index e97cd2d779..c0a7bc54d4 100644 > --- a/util/meson.build > +++ b/util/meson.build > @@ -1,5 +1,5 @@ > util_ss.add(files('osdep.c', 'cutils.c', 'unicode.c', 'qemu-timer-common.c')) > -util_ss.add(files('thread-context.c')) > +util_ss.add(files('thread-context.c'), numa) > if not config_host_data.get('CONFIG_ATOMIC64') > util_ss.add(files('atomic64.c')) > endif > > > I wonder if there is some conditional we could use to avoid the apparently useless dependency to libnuma in the qemu-img binary? the simplest change is probably moving the thread-context stuff out of util (as you say, it's currently only used by QEMU itself).
Hello David, It would seem to me that a lot of the calling code like qemu_prealloc_mem for example should be sysemu-only, not used for tools, or user mode either right? And the thread_context.c itself should also be sysemu-only, correct? Thanks, Claudio On 2/5/24 15:15, David Hildenbrand wrote: > On 05.02.24 11:14, Claudio Fontana wrote: >> Hi, > > Hi Claudio, > >> >> turning pages back in time, >> >> noticed that in recent qemu-img binaries we include an ELF dependency on libnuma.so that seems unused. >> >> I think it stems from this commit: >> >> commit 10218ae6d006f76410804cc4dc690085b3d008b5 >> Author: David Hildenbrand <david@redhat.com> >> Date: Fri Oct 14 15:47:17 2022 +0200 >> >> util: Add write-only "node-affinity" property for ThreadContext >> >> >> possibly this hunk? >> >> diff --git a/util/meson.build b/util/meson.build >> index e97cd2d779..c0a7bc54d4 100644 >> --- a/util/meson.build >> +++ b/util/meson.build >> @@ -1,5 +1,5 @@ >> util_ss.add(files('osdep.c', 'cutils.c', 'unicode.c', 'qemu-timer-common.c')) >> -util_ss.add(files('thread-context.c')) >> +util_ss.add(files('thread-context.c'), numa) >> if not config_host_data.get('CONFIG_ATOMIC64') >> util_ss.add(files('atomic64.c')) >> endif >> >> >> I wonder if there is some conditional we could use to avoid the apparently useless dependency to libnuma in the qemu-img binary? > > the simplest change is probably moving the thread-context stuff out of > util (as you say, it's currently only used by QEMU itself). >
On 05.02.24 17:13, Claudio Fontana wrote: > Hello David, > Hi, > It would seem to me that a lot of the calling code like qemu_prealloc_mem for example > should be sysemu-only, not used for tools, or user mode either right? > > And the thread_context.c itself should also be sysemu-only, correct? Yes, both should currently only get used for sysemu only. Memory backends and virtio-mem are sysemu-only.
diff --git a/qapi/qom.json b/qapi/qom.json index 8013ba4b82..20b5735d78 100644 --- a/qapi/qom.json +++ b/qapi/qom.json @@ -839,10 +839,17 @@ # threads created in the thread context (default: QEMU main # thread CPU affinity) # +# @node-affinity: the list of host node numbers that will be resolved to a +# list of host CPU numbers used as CPU affinity. This is a +# shortcut for specifying the list of host CPU numbers +# belonging to the host nodes manually by setting +# @cpu-affinity. (default: QEMU main thread affinity) +# # Since: 7.2 ## { 'struct': 'ThreadContextProperties', - 'data': { '*cpu-affinity': ['uint16'] } } + 'data': { '*cpu-affinity': ['uint16'], + '*node-affinity': ['uint16'] } } ## diff --git a/util/meson.build b/util/meson.build index e97cd2d779..c0a7bc54d4 100644 --- a/util/meson.build +++ b/util/meson.build @@ -1,5 +1,5 @@ util_ss.add(files('osdep.c', 'cutils.c', 'unicode.c', 'qemu-timer-common.c')) -util_ss.add(files('thread-context.c')) +util_ss.add(files('thread-context.c'), numa) if not config_host_data.get('CONFIG_ATOMIC64') util_ss.add(files('atomic64.c')) endif diff --git a/util/thread-context.c b/util/thread-context.c index c921905396..4138245332 100644 --- a/util/thread-context.c +++ b/util/thread-context.c @@ -21,6 +21,10 @@ #include "qemu/module.h" #include "qemu/bitmap.h" +#ifdef CONFIG_NUMA +#include <numa.h> +#endif + enum { TC_CMD_NONE = 0, TC_CMD_STOP, @@ -88,6 +92,11 @@ static void thread_context_set_cpu_affinity(Object *obj, Visitor *v, int nbits = 0, ret; Error *err = NULL; + if (tc->init_cpu_bitmap) { + error_setg(errp, "Mixing CPU and node affinity not supported"); + return; + } + visit_type_uint16List(v, name, &host_cpus, &err); if (err) { error_propagate(errp, err); @@ -159,6 +168,79 @@ static void thread_context_get_cpu_affinity(Object *obj, Visitor *v, qapi_free_uint16List(host_cpus); } +static void thread_context_set_node_affinity(Object *obj, Visitor *v, + const char *name, void *opaque, + Error **errp) +{ +#ifdef CONFIG_NUMA + const int nbits = numa_num_possible_cpus(); + ThreadContext *tc = THREAD_CONTEXT(obj); + uint16List *l, *host_nodes = NULL; + unsigned long *bitmap = NULL; + struct bitmask *tmp_cpus; + Error *err = NULL; + int ret, i; + + if (tc->init_cpu_bitmap) { + error_setg(errp, "Mixing CPU and node affinity not supported"); + return; + } + + visit_type_uint16List(v, name, &host_nodes, &err); + if (err) { + error_propagate(errp, err); + return; + } + + if (!host_nodes) { + error_setg(errp, "Node list is empty"); + goto out; + } + + bitmap = bitmap_new(nbits); + tmp_cpus = numa_allocate_cpumask(); + for (l = host_nodes; l; l = l->next) { + numa_bitmask_clearall(tmp_cpus); + ret = numa_node_to_cpus(l->value, tmp_cpus); + if (ret) { + /* We ignore any errors, such as impossible nodes. */ + continue; + } + for (i = 0; i < nbits; i++) { + if (numa_bitmask_isbitset(tmp_cpus, i)) { + set_bit(i, bitmap); + } + } + } + numa_free_cpumask(tmp_cpus); + + if (bitmap_empty(bitmap, nbits)) { + error_setg(errp, "The nodes select no CPUs"); + goto out; + } + + if (tc->thread_id != -1) { + /* + * Note: we won't be adjusting the affinity of any thread that is still + * around for now, but only the affinity of the context thread. + */ + ret = qemu_thread_set_affinity(&tc->thread, bitmap, nbits); + if (ret) { + error_setg(errp, "Setting CPU affinity failed: %s", strerror(ret)); + } + } else { + tc->init_cpu_bitmap = bitmap; + bitmap = NULL; + tc->init_cpu_nbits = nbits; + } +out: + g_free(bitmap); + qapi_free_uint16List(host_nodes); +#else + error_setg(errp, "NUMA node affinity is not supported by this QEMU"); +#endif +} + static void thread_context_get_thread_id(Object *obj, Visitor *v, const char *name, void *opaque, Error **errp) @@ -208,6 +290,8 @@ static void thread_context_class_init(ObjectClass *oc, void *data) object_class_property_add(oc, "cpu-affinity", "int", thread_context_get_cpu_affinity, thread_context_set_cpu_affinity, NULL, NULL); + object_class_property_add(oc, "node-affinity", "int", NULL, + thread_context_set_node_affinity, NULL, NULL); } static void thread_context_instance_init(Object *obj)
Let's make it easier to pin threads created via a ThreadContext to all host CPUs currently belonging to a given set of host NUMA nodes -- which is the common case. "node-affinity" is simply a shortcut for setting "cpu-affinity" manually to the list of host CPUs belonging to the set of host nodes. This property can only be written. A simple QEMU example to set the CPU affinity to host node 1 on a system with two nodes, 24 CPUs each, whereby odd-numbered host CPUs belong to host node 1: qemu-system-x86_64 -S \ -object thread-context,id=tc1,node-affinity=1 And we can query the cpu-affinity via HMP/QMP: (qemu) qom-get tc1 cpu-affinity [ 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47 ] We cannot query the node-affinity: (qemu) qom-get tc1 node-affinity Error: Insufficient permission to perform this operation But note that due to dynamic library loading this example will not work before we actually make use of thread_context_create_thread() in QEMU code, because the type will otherwise not get registered. We'll wire this up next to make it work. Note that if the host CPUs for a host node change due do CPU hot(un)plug CPU onlining/offlining (i.e., lscpu output changes) after the ThreadContext was started, the CPU affinity will not get updated. Reviewed-by: Michal Privoznik <mprivozn@redhat.com> Acked-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20221014134720.168738-5-david@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> --- qapi/qom.json | 9 ++++- util/meson.build | 2 +- util/thread-context.c | 84 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 93 insertions(+), 2 deletions(-)