On 2/6/24 19:24, Pierrick Bouvier wrote:
We introduce a cpu local storage, automatically managed (and extended)
by QEMU itself. Plugin allocate a scoreboard, and don't have to deal
with how many cpus are launched.
This API will be used by new inline functions but callbacks can benefit
from this as well. This way, they can operate without a global lock for
simple operations.
At any point during execution, any scoreboard will be dimensioned with
at least qemu_plugin_num_vcpus entries.
New functions:
- qemu_plugin_scoreboard_find
- qemu_plugin_scoreboard_free
- qemu_plugin_scoreboard_new
In more, we define a qemu_plugin_u64, which is a simple struct holding
a pointer to a scoreboard, and a given offset.
This allows to have a scoreboard containing structs, without having to
bring offset for all operations on a specific field.
Since most of the plugins are simply collecting a sum of per-cpu values,
qemu_plugin_u64 directly support this operation as well.
New functions:
- qemu_plugin_u64_add
- qemu_plugin_u64_get
- qemu_plugin_u64_set
- qemu_plugin_u64_sum
New macros:
- qemu_plugin_scoreboard_u64
- qemu_plugin_scoreboard_u64_in_struct
I think the u64 stuff should be a second patch built upon the basic scoreboard
support.
+/* A scoreboard is an array of values, indexed by vcpu_index */
+struct qemu_plugin_scoreboard {
+ GArray *data;
+};
Unnecessary? Generates an extra pointer dereference for no apparent benefit.
Alternately, might be useful for other data structure changes...
+/**
+ * typedef qemu_plugin_u64 - uint64_t member of an entry in a scoreboard
+ *
+ * This field allows to access a specific uint64_t member in one given entry,
+ * located at a specified offset. Inline operations expect this as entry.
+ */
+typedef struct {
+ struct qemu_plugin_scoreboard *score;
Embed the struct instead?
@@ -31,6 +31,9 @@ struct qemu_plugin_state {
* but with the HT we avoid adding a field to CPUState.
*/
GHashTable *cpu_ht;
+ /* Scoreboards, indexed by their addresses. */
+ GHashTable *scoreboards;
Why a hash table? All you want is to be able to iterate through all, and add/remove
easily. Seems like QLIST from <qemu/queue.h> would be better, and the QLIST_ENTRY member
would make struct qemu_plugin_scoreboard useful.
r~
