diff mbox series

[v2,06/14] contrib/plugins: allow setting of instructions per quantum

Message ID 20250506125715.232872-7-alex.bennee@linaro.org
State New
Headers show
Series Maintainer updates for May (testing, plugins, virtio-gpu) | expand

Commit Message

Alex Bennée May 6, 2025, 12:57 p.m. UTC 
The default is we update time every 1/10th of a second or so. However
for some cases we might want to update time more frequently. Allow
this to be set via the command line through the ipq argument.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>

---
v2
  - checkpatch fixes.
---
 docs/about/emulation.rst |  4 ++++
 contrib/plugins/ips.c    | 10 +++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

Comments

Akihiko Odaki May 10, 2025, 4:45 a.m. UTC | #1 
On 2025/05/06 21:57, Alex Bennée wrote:
> The default is we update time every 1/10th of a second or so. However
> for some cases we might want to update time more frequently. Allow
> this to be set via the command line through the ipq argument.
> 
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
> 
> ---
> v2
>    - checkpatch fixes.
> ---
>   docs/about/emulation.rst |  4 ++++
>   contrib/plugins/ips.c    | 10 +++++++++-
>   2 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/docs/about/emulation.rst b/docs/about/emulation.rst
> index a72591ee4d..456d01d5b0 100644
> --- a/docs/about/emulation.rst
> +++ b/docs/about/emulation.rst
> @@ -811,6 +811,10 @@ This plugin can limit the number of Instructions Per Second that are executed::
>     * - ips=N
>       - Maximum number of instructions per cpu that can be executed in one second.
>         The plugin will sleep when the given number of instructions is reached.
> +  * - ipq=N
> +    - Instructions per quantum. How many instructions before we re-calculate time.
> +      The lower the number the more accurate time will be, but the less efficient the plugin.
> +      Defaults to ips/10
>   
>   Other emulation features
>   ------------------------
> diff --git a/contrib/plugins/ips.c b/contrib/plugins/ips.c
> index 9b166a7d6c..62ed8ddd08 100644
> --- a/contrib/plugins/ips.c
> +++ b/contrib/plugins/ips.c
> @@ -147,6 +147,8 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
>                                              const qemu_info_t *info, int argc,
>                                              char **argv)
>   {
> +    bool ipq_set = false;
> +
>       for (int i = 0; i < argc; i++) {
>           char *opt = argv[i];
>           g_auto(GStrv) tokens = g_strsplit(opt, "=", 2);
> @@ -177,6 +179,9 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
>                       return -1;
>                   }
>               }
> +        } else if (g_strcmp0(tokens[0], "ipq") == 0) {
> +            max_insn_per_quantum = g_ascii_strtoull(tokens[1], NULL, 10);

It may be nice to have an error check performed for ips.

> +            ipq_set = true;
>           } else {
>               fprintf(stderr, "option parsing failed: %s\n", opt);
>               return -1;
> @@ -184,7 +189,10 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
>       }
>   
>       vcpus = qemu_plugin_scoreboard_new(sizeof(vCPUTime));
> -    max_insn_per_quantum = max_insn_per_second / NUM_TIME_UPDATE_PER_SEC;
> +
> +    if (!ipq_set) {
> +        max_insn_per_quantum = max_insn_per_second / NUM_TIME_UPDATE_PER_SEC;
> +    }
>   
>       if (max_insn_per_quantum == 0) {
>           fprintf(stderr, "minimum of %d instructions per second needed\n",
diff mbox series

Patch

diff --git a/docs/about/emulation.rst b/docs/about/emulation.rst
index a72591ee4d..456d01d5b0 100644
--- a/docs/about/emulation.rst
+++ b/docs/about/emulation.rst
@@ -811,6 +811,10 @@  This plugin can limit the number of Instructions Per Second that are executed::
   * - ips=N
     - Maximum number of instructions per cpu that can be executed in one second.
       The plugin will sleep when the given number of instructions is reached.
+  * - ipq=N
+    - Instructions per quantum. How many instructions before we re-calculate time.
+      The lower the number the more accurate time will be, but the less efficient the plugin.
+      Defaults to ips/10
 
 Other emulation features
 ------------------------
diff --git a/contrib/plugins/ips.c b/contrib/plugins/ips.c
index 9b166a7d6c..62ed8ddd08 100644
--- a/contrib/plugins/ips.c
+++ b/contrib/plugins/ips.c
@@ -147,6 +147,8 @@  QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
                                            const qemu_info_t *info, int argc,
                                            char **argv)
 {
+    bool ipq_set = false;
+
     for (int i = 0; i < argc; i++) {
         char *opt = argv[i];
         g_auto(GStrv) tokens = g_strsplit(opt, "=", 2);
@@ -177,6 +179,9 @@  QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
                     return -1;
                 }
             }
+        } else if (g_strcmp0(tokens[0], "ipq") == 0) {
+            max_insn_per_quantum = g_ascii_strtoull(tokens[1], NULL, 10);
+            ipq_set = true;
         } else {
             fprintf(stderr, "option parsing failed: %s\n", opt);
             return -1;
@@ -184,7 +189,10 @@  QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
     }
 
     vcpus = qemu_plugin_scoreboard_new(sizeof(vCPUTime));
-    max_insn_per_quantum = max_insn_per_second / NUM_TIME_UPDATE_PER_SEC;
+
+    if (!ipq_set) {
+        max_insn_per_quantum = max_insn_per_second / NUM_TIME_UPDATE_PER_SEC;
+    }
 
     if (max_insn_per_quantum == 0) {
         fprintf(stderr, "minimum of %d instructions per second needed\n",