[PATCH] eal/unix: allow creating thread with real-time priority
Thomas Monjalon
thomas at monjalon.net
Tue Oct 24 14:54:16 CEST 2023
When adding an API for creating threads,
the real-time priority has been forbidden on Unix.
There is a known issue with ring behaviour,
but it should not be completely forbidden.
Fixes: ca04c78b6262 ("eal: get/set thread priority per thread identifier")
Fixes: ce6e911d20f6 ("eal: add thread lifetime API")
Fixes: a7ba40b2b1bf ("drivers: convert to internal control threads")
Cc: stable at dpdk.org
Signed-off-by: Thomas Monjalon <thomas at monjalon.net>
---
app/test/test_threads.c | 9 ---------
doc/guides/prog_guide/env_abstraction_layer.rst | 4 +++-
lib/eal/include/rte_thread.h | 2 +-
lib/eal/unix/rte_thread.c | 9 ---------
4 files changed, 4 insertions(+), 20 deletions(-)
diff --git a/app/test/test_threads.c b/app/test/test_threads.c
index 4ac3f2671a..4f7d10e074 100644
--- a/app/test/test_threads.c
+++ b/app/test/test_threads.c
@@ -97,21 +97,12 @@ test_thread_priority(void)
"Priority set mismatches priority get");
priority = RTE_THREAD_PRIORITY_REALTIME_CRITICAL;
-#ifndef RTE_EXEC_ENV_WINDOWS
- RTE_TEST_ASSERT(rte_thread_set_priority(thread_id, priority) == ENOTSUP,
- "Priority set to critical should fail");
- RTE_TEST_ASSERT(rte_thread_get_priority(thread_id, &priority) == 0,
- "Failed to get thread priority");
- RTE_TEST_ASSERT(priority == RTE_THREAD_PRIORITY_NORMAL,
- "Failed set to critical should have retained normal");
-#else
RTE_TEST_ASSERT(rte_thread_set_priority(thread_id, priority) == 0,
"Priority set to critical should succeed");
RTE_TEST_ASSERT(rte_thread_get_priority(thread_id, &priority) == 0,
"Failed to get thread priority");
RTE_TEST_ASSERT(priority == RTE_THREAD_PRIORITY_REALTIME_CRITICAL,
"Priority set mismatches priority get");
-#endif
priority = RTE_THREAD_PRIORITY_NORMAL;
RTE_TEST_ASSERT(rte_thread_set_priority(thread_id, priority) == 0,
diff --git a/doc/guides/prog_guide/env_abstraction_layer.rst b/doc/guides/prog_guide/env_abstraction_layer.rst
index 6debf54efb..d1f7cae7cd 100644
--- a/doc/guides/prog_guide/env_abstraction_layer.rst
+++ b/doc/guides/prog_guide/env_abstraction_layer.rst
@@ -815,7 +815,9 @@ Known Issues
4. It MAY be used by preemptible multi-producer and/or preemptible multi-consumer pthreads whose scheduling policy are all SCHED_OTHER(cfs), SCHED_IDLE or SCHED_BATCH. User SHOULD be aware of the performance penalty before using it.
- 5. It MUST not be used by multi-producer/consumer pthreads, whose scheduling policies are SCHED_FIFO or SCHED_RR.
+ 5. It MUST not be used by multi-producer/consumer pthreads
+ whose scheduling policies are ``SCHED_FIFO``
+ or ``SCHED_RR`` (``RTE_THREAD_PRIORITY_REALTIME_CRITICAL``).
Alternatively, applications can use the lock-free stack mempool handler. When
considering this handler, note that:
diff --git a/lib/eal/include/rte_thread.h b/lib/eal/include/rte_thread.h
index 8da9d4d3fb..5e624015e4 100644
--- a/lib/eal/include/rte_thread.h
+++ b/lib/eal/include/rte_thread.h
@@ -59,7 +59,7 @@ enum rte_thread_priority {
RTE_THREAD_PRIORITY_NORMAL = 0,
/**< normal thread priority, the default */
RTE_THREAD_PRIORITY_REALTIME_CRITICAL = 1,
- /**< highest thread priority allowed */
+ /**< highest thread priority, use with caution */
};
/**
diff --git a/lib/eal/unix/rte_thread.c b/lib/eal/unix/rte_thread.c
index 36a21ab2f9..0ff291c6f1 100644
--- a/lib/eal/unix/rte_thread.c
+++ b/lib/eal/unix/rte_thread.c
@@ -153,11 +153,6 @@ rte_thread_create(rte_thread_t *thread_id,
goto cleanup;
}
- if (thread_attr->priority ==
- RTE_THREAD_PRIORITY_REALTIME_CRITICAL) {
- ret = ENOTSUP;
- goto cleanup;
- }
ret = thread_map_priority_to_os_value(thread_attr->priority,
¶m.sched_priority, &policy);
if (ret != 0)
@@ -275,10 +270,6 @@ rte_thread_set_priority(rte_thread_t thread_id,
int policy;
int ret;
- /* Realtime priority can cause crashes on non-Windows platforms. */
- if (priority == RTE_THREAD_PRIORITY_REALTIME_CRITICAL)
- return ENOTSUP;
-
ret = thread_map_priority_to_os_value(priority, ¶m.sched_priority,
&policy);
if (ret != 0)
--
2.42.0
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