Re: [dpdk-dev] [PATCH v2 4/4] eventdev: relax smp barriers with c11 atomics

06/07/2020 17:32, Phil Yang:

From: Thomas Monjalon <redacted>

quoted

02/07/2020 07:26, Phil Yang:

quoted

--- a/lib/librte_eventdev/rte_event_timer_adapter.h
+++ b/lib/librte_eventdev/rte_event_timer_adapter.h

@@ -467,7 +467,7 @@ struct rte_event_timer {
 	 *  - op: RTE_EVENT_OP_NEW
 	 *  - event_type: RTE_EVENT_TYPE_TIMER
 	 */
-	volatile enum rte_event_timer_state state;
+	enum rte_event_timer_state state;
 	/**< State of the event timer. */

Why do you remove the volatile keyword?
It is not explained in the commit log.

By using the C11 atomic operations, it will generate the same instructions for non-volatile and volatile version.
Please check the sample code here: https://gcc.godbolt.org/z/8x5rWs

quoted

This change is triggering a warning in the ABI check:
http://mails.dpdk.org/archives/test-report/2020-July/140440.html
Moving from volatile to non-volatile is probably not an issue.
I expect the code generated for the volatile case to work the same
in non-volatile case. Do you confirm?

They generate the same instructions, so either way will work.
Do I need to revert it to the volatile version?

Either you revert, or you add explanation in the commit log
+ exception in libabigail.abignore