Re: [PATCH v1 1/1] eal: warn user when lcore cpuset includes multiple sockets

[Burakov, Anatoly]

On 5/23/2023 2:55 PM, Bruce Richardson wrote:
On Tue, May 23, 2023 at 01:06:16PM +0000, Anatoly Burakov wrote:
Currently, it is allowed to specify a cpuset for lcores such that it
will include physical cores from different NUMA nodes. This has an
effect of setting `rte_socket_id()` for that lcore to SOCKET_ID_ANY,
so add a warning about it.
Signed-off-by: Anatoly Burakov <anatoly.bura...@intel.com>
---
  lib/eal/common/eal_common_thread.c | 20 +++++++++++++++++---
  1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/lib/eal/common/eal_common_thread.c 
b/lib/eal/common/eal_common_thread.c
index 079a385630..46fd2aca1e 100644
--- a/lib/eal/common/eal_common_thread.c
+++ b/lib/eal/common/eal_common_thread.c
@@ -65,10 +65,13 @@ static void
  thread_update_affinity(rte_cpuset_t *cpusetp)
  {
        unsigned int lcore_id = rte_lcore_id();
+       int socket_id;
+
+       /* find socket ID from cpuset */
+       socket_id = eal_cpuset_socket_id(cpusetp);
  
  	/* store socket_id in TLS for quick access */
-       RTE_PER_LCORE(_socket_id) =
-               eal_cpuset_socket_id(cpusetp);
+       RTE_PER_LCORE(_socket_id) = socket_id;
  
  	/* store cpuset in TLS for quick access */
        memmove(&RTE_PER_LCORE(_cpuset), cpusetp,
@@ -76,9 +79,20 @@ thread_update_affinity(rte_cpuset_t *cpusetp)
  
  	if (lcore_id != (unsigned)LCORE_ID_ANY) {
                /* EAL thread will update lcore_config */
-               lcore_config[lcore_id].socket_id = RTE_PER_LCORE(_socket_id);
+               lcore_config[lcore_id].socket_id = socket_id;
                memmove(&lcore_config[lcore_id].cpuset, cpusetp,
                        sizeof(rte_cpuset_t));
+               
+               /*
+                * lcore_id is not LCORE_ID_ANY, meaning this is a DPDK lcore,
+                * so having a valid NUMA affinity for this lcore is important.
+                * However, if cpuset includes cores from multiple NUMA nodes,
+                * the socket ID will be set to SOCKET_ID_ANY. Notify the user
+                * about it if that happens.
+                */
+               if (socket_id == SOCKET_ID_ANY)
+                       RTE_LOG(INFO, EAL, "DPDK lcore %u has NUMA affinity set to 
SOCKET_ID_ANY\n",
+                                       lcore_id);
        }
  }
While having a warning comment in the code is good, should we not also have
a user visible warning to the user when the specific a corelist parameter
value which includes the cross-socket scenario?

/Bruce

We could, yes. We could walk through the cpuset for a given lcore, and 
list their socket ID's, would that work?

--
Thanks,
Anatoly