[Devel] [PATCH VZ9 v2] fs/fuse kio: do not set RPC affinity from a workequeue worker

[Liu Kui]

A RPC's affinity shouldn't be set from a workqueue worker in case of
RPC_AFFINITY_RETENT mode, otherwise the RPC could be stuck to one cpu
forever. When multiple rpcs are stuck to the same cpu overall performance
degrades significantly.

Fixes: #VSTOR-109481
https://virtuozzo.atlassian.net/browse/VSTOR-109481

Signed-off-by: Liu Kui <kui.liu at virtuozzo.com>
---
 fs/fuse/kio/pcs/pcs_rpc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/fuse/kio/pcs/pcs_rpc.c b/fs/fuse/kio/pcs/pcs_rpc.c
index f15d0c3fb7cd..c7d387568b95 100644
--- a/fs/fuse/kio/pcs/pcs_rpc.c
+++ b/fs/fuse/kio/pcs/pcs_rpc.c
@@ -877,6 +877,10 @@ static void pcs_rpc_affinity(struct pcs_rpc *ep, bool was_idle)
 				pcs_rpc_cpu_select(ep);
 			break;
 		case RPC_AFFINITY_RETENT:
+			/* Do not set rpc affinity from a workequeue worker */
+			if (current->flags & PF_WQ_WORKER)
+				break;
+
 			/* Naive socket-to-cpu binding approach */
 			if (ep->cpu == WORK_CPU_UNBOUND ||
 			    (time_is_before_jiffies(ep->cpu_stamp) && was_idle)) {
-- 
2.39.5 (Apple Git-154)