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Re: [Qemu-devel] [PATCH v2] qobject: Replace property list with GHashTab
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] [PATCH v2] qobject: Replace property list with GHashTable |
Date: |
Thu, 8 Oct 2015 11:19:54 +0100 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
Nit-pick on subject line - s/qobject/qom/ and also copy
Andreas Färber on the patch, since he's the primary
maintainer of the QOM subsystem.
On Tue, Oct 06, 2015 at 04:48:53PM +0300, Pavel Fedin wrote:
> ARM GICv3 systems with large number of CPUs create lots of IRQ pins. Since
> every pin is represented as a property, number of these properties becomes
> very large. Every property add first makes sure there's no duplicates.
> Traversing the list becomes very slow, therefore qemu initialization takes
> significant time (several seconds for e. g. 16 CPUs).
>
> This patch replaces list with GHashTable, making lookup very fast. The only
> drawback is that object_child_foreach() and object_child_foreach_recursive()
> cannot modify their objects during traversal, since GHashTableIter does not
> have modify-safe version. However, the code seems not to modify objects via
> these functions.
>
> Signed-off-by: Pavel Fedin <address@hidden>
> ---
> v1 => v2:
> - Fixed stupid bug in object_unparent(), use correct object
> ---
> include/qom/object.h | 4 +--
> qmp.c | 8 +++--
> qom/object.c | 98
> +++++++++++++++++++++++-----------------------------
> vl.c | 4 ++-
> 4 files changed, 54 insertions(+), 60 deletions(-)
>
> diff --git a/include/qom/object.h b/include/qom/object.h
> index be7280c..b100923 100644
> --- a/include/qom/object.h
> +++ b/include/qom/object.h
> @@ -345,7 +345,7 @@ typedef struct ObjectProperty
> ObjectPropertyRelease *release;
> void *opaque;
>
> - QTAILQ_ENTRY(ObjectProperty) node;
> + Object *obj;
I have a patch which adds property registration against the
class, so requiring ObjectProperty to have a back-poointer
to an object instance is not desirable.
> diff --git a/qom/object.c b/qom/object.c
> index 4805328..1c7c42a 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -326,6 +326,20 @@ static void object_post_init_with_type(Object *obj,
> TypeImpl *ti)
> }
> }
>
> +static void property_destroy(gpointer data)
> +{
> + ObjectProperty *prop = data;
> +
> + if (prop->release) {
> + prop->release(prop->obj, prop->name, prop->opaque);
> + }
Instead of calling the release() callback here, use a hash iterator
to call it from the object_finalize() method, before unref'ing the
hash table, and also call it from objecT_property_del directly. That
way you don't need to store the Object * back pointer in the
ObjectProperty struct.
> +
> + g_free(prop->name);
> + g_free(prop->type);
> + g_free(prop->description);
> + g_free(prop);
> +}
> @@ -410,7 +404,7 @@ static void object_finalize(void *data)
> Object *obj = data;
> TypeImpl *ti = obj->class->type;
>
> - object_property_del_all(obj);
> + g_hash_table_unref(obj->properties);
> object_deinit(obj, ti);
>
> g_assert(obj->ref == 0);
> void object_property_del(Object *obj, const char *name, Error **errp)
> {
> - ObjectProperty *prop = object_property_find(obj, name, errp);
> - if (prop == NULL) {
> + if (g_hash_table_remove(obj->properties, name)) {
> return;
> }
>
> - if (prop->release) {
> - prop->release(obj, name, prop->opaque);
> - }
> -
> - QTAILQ_REMOVE(&obj->properties, prop, node);
> -
> - g_free(prop->name);
> - g_free(prop->type);
> - g_free(prop->description);
> - g_free(prop);
> + error_setg(errp, "Property '.%s' not found", name);
> }
Overall I think this is a good improvement to make
Regards,
Daniel
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