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[Qemu-devel] Ping: [PATCH] qobject: object_property_add() performance im
From: |
Pavel Fedin |
Subject: |
[Qemu-devel] Ping: [PATCH] qobject: object_property_add() performance improvement |
Date: |
Thu, 04 Jun 2015 10:35:17 +0300 |
Hello Luiz! Have you missed this ?
Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia
> -----Original Message-----
> From: address@hidden [mailto:qemu-devel-
> address@hidden On Behalf Of Pavel Fedin
> Sent: Thursday, May 28, 2015 11:42 AM
> To: address@hidden
> Cc: 'Luiz Capitulino'
> Subject: [Qemu-devel] [PATCH] qobject: object_property_add() performance
> improvement
>
> The function originally behaves very badly when adding properties with "[*]"
> suffix.
> Nomnally these are used for numbering IRQ pins. In order to find the correct
> starting
> number the function started from zero and checked for duplicates. This took
> incredibly
> long time with large number of CPUs because number of IRQ pins on some
> architectures
(like
> ARM GICv3) gets multiplied by number of CPUs.
> The solution is to add one more property which caches last used index so that
duplication
> check is not repeated thousands of times. Every time an array is expanded the
> index is
> picked up from this cache. Cache property is a uint32_t and has the original
> name of the
> array ('name[*]') for simplicity.
> Some more improvements:
> - Call object_property_add_single() instead of recursing into itself - keeps
> off
memcmp()
> check every time when its result is already known.
> - Allocate name_no_array only once and not every time for every property
> (there can be
> thousands of them)
> The modification decreases qemu startup time with 32 ARMv8 CPUs by a factor
> of 2 (~10
sec
> vs ~20 sec).
>
> Signed-off-by: Pavel Fedin <address@hidden>
> ---
> qom/object.c | 89
> ++++++++++++++++++++++++++++++++++++++++++------------------
> 1 file changed, 62 insertions(+), 27 deletions(-)
>
> diff --git a/qom/object.c b/qom/object.c
> index b8dff43..72480bc 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -10,6 +10,8 @@
> * See the COPYING file in the top-level directory.
> */
>
> +#include <glib/gprintf.h>
> +
> #include "qom/object.h"
> #include "qemu-common.h"
> #include "qapi/visitor.h"
> @@ -721,35 +723,14 @@ void object_unref(Object *obj)
> }
> }
>
> -ObjectProperty *
> -object_property_add(Object *obj, const char *name, const char *type,
> - ObjectPropertyAccessor *get,
> - ObjectPropertyAccessor *set,
> - ObjectPropertyRelease *release,
> - void *opaque, Error **errp)
> +static ObjectProperty *
> +object_property_add_single(Object *obj, const char *name, const char *type,
> + ObjectPropertyAccessor *get,
> + ObjectPropertyAccessor *set,
> + ObjectPropertyRelease *release,
> + void *opaque, Error **errp)
> {
> ObjectProperty *prop;
> - size_t name_len = strlen(name);
> -
> - if (name_len >= 3 && !memcmp(name + name_len - 3, "[*]", 4)) {
> - int i;
> - ObjectProperty *ret;
> - char *name_no_array = g_strdup(name);
> -
> - name_no_array[name_len - 3] = '\0';
> - for (i = 0; ; ++i) {
> - char *full_name = g_strdup_printf("%s[%d]", name_no_array, i);
> -
> - ret = object_property_add(obj, full_name, type, get, set,
> - release, opaque, NULL);
> - g_free(full_name);
> - if (ret) {
> - break;
> - }
> - }
> - g_free(name_no_array);
> - return ret;
> - }
>
> QTAILQ_FOREACH(prop, &obj->properties, node) {
> if (strcmp(prop->name, name) == 0) {
> @@ -774,6 +755,60 @@ object_property_add(Object *obj, const char *name, const
> char
*type,
> return prop;
> }
>
> +static void property_get_uint32_ptr(Object *obj, Visitor *v,
> + void *opaque, const char *name,
> + Error **errp);
> +
> +ObjectProperty *
> +object_property_add(Object *obj, const char *name, const char *type,
> + ObjectPropertyAccessor *get,
> + ObjectPropertyAccessor *set,
> + ObjectPropertyRelease *release,
> + void *opaque, Error **errp)
> +{
> + size_t name_len = strlen(name);
> +
> + if (name_len >= 3 && !memcmp(name + name_len - 3, "[*]", 4)) {
> + int i;
> + ObjectProperty *ret, *count;
> + /* 10 characters for maximum possible integer number */
> + char *name_no_array = g_malloc(name_len + 10);
> +
> + count = object_property_find(obj, name, NULL);
> + if (count == NULL) {
> + void *v = g_malloc0(sizeof(uint32_t));
> +
> + /* This is the same as object_property_add_uint32_ptr(), but:
> + * - Slightly faster and returns pointer
> + * - Will not recurse here so that we can use
> + * raw name with [*] here */
> + count = object_property_add_single(obj, name, "uint32",
> + property_get_uint32_ptr, NULL,
> + NULL, v, &error_abort);
> + }
> +
> + name_len -= 2;
> + memcpy(name_no_array, name, name_len);
> +
> + for (i = *((uint32_t *)count->opaque); ; ++i) {
> + g_sprintf(&name_no_array[name_len], "%d]", i);
> +
> + ret = object_property_add_single(obj, name_no_array, type, get,
> set,
> + release, opaque, NULL);
> + if (ret) {
> + break;
> + }
> + }
> + *((uint32_t *)count->opaque) = i + 1;
> +
> + g_free(name_no_array);
> + return ret;
> + }
> +
> + return object_property_add_single(obj, name, type,
> + get, set, release, opaque, errp);
> +}
> +
> ObjectProperty *object_property_find(Object *obj, const char *name,
> Error **errp)
> {
> --
> 1.9.5.msysgit.0
>
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Pavel Fedin <=