From: Chuck Lever Date: Wed, 6 May 2026 15:26:50 +0000 (-0400) Subject: svcrdma: Release write chunk resources without re-queuing X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9545262f7e58d67de413d5a47ea2a3f2e59ba9f6;p=thirdparty%2Fkernel%2Flinux.git svcrdma: Release write chunk resources without re-queuing Each RDMA Send completion triggers a cascade of work items on the svcrdma_wq unbound workqueue: ib_cq_poll_work (on ib_comp_wq, per-CPU) -> svc_rdma_send_ctxt_put -> queue_work [work item 1] -> svc_rdma_write_info_free -> queue_work [work item 2] Every transition through queue_work contends on the unbound pool's spinlock. Profiling an 8KB NFSv3 read/write workload over RDMA shows about 4% of total CPU cycles spent on this lock, with the cascading re-queue of write_info release contributing roughly 1%. The initial queue_work in svc_rdma_send_ctxt_put is needed to move release work off the CQ completion context (which runs on a per-CPU bound workqueue). However, once executing on svcrdma_wq, there is no need to re-queue for each write_info structure. svc_rdma_reply_chunk_release already calls svc_rdma_cc_release inline from the same svcrdma_wq context, and svc_rdma_recv_ctxt_put does the same from nfsd thread context. Release write chunk resources inline in svc_rdma_write_info_free, removing the intermediate svc_rdma_write_info_free_async work item and the wi_work field from struct svc_rdma_write_info. Reviewed-by: Mike Snitzer Tested-by: Jonathan Flynn Signed-off-by: Chuck Lever --- diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h index df6e08aaad570..14eb9d52742ef 100644 --- a/include/linux/sunrpc/svc_rdma.h +++ b/include/linux/sunrpc/svc_rdma.h @@ -230,7 +230,6 @@ struct svc_rdma_write_info { unsigned int wi_next_off; struct svc_rdma_chunk_ctxt wi_cc; - struct work_struct wi_work; }; struct svc_rdma_send_ctxt { diff --git a/net/sunrpc/xprtrdma/svc_rdma_rw.c b/net/sunrpc/xprtrdma/svc_rdma_rw.c index 402e2ceca4ff7..cca8ec973de4b 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_rw.c +++ b/net/sunrpc/xprtrdma/svc_rdma_rw.c @@ -236,21 +236,12 @@ svc_rdma_write_info_alloc(struct svcxprt_rdma *rdma, return info; } -static void svc_rdma_write_info_free_async(struct work_struct *work) +static void svc_rdma_write_info_free(struct svc_rdma_write_info *info) { - struct svc_rdma_write_info *info; - - info = container_of(work, struct svc_rdma_write_info, wi_work); svc_rdma_cc_release(info->wi_rdma, &info->wi_cc, DMA_TO_DEVICE); kfree(info); } -static void svc_rdma_write_info_free(struct svc_rdma_write_info *info) -{ - INIT_WORK(&info->wi_work, svc_rdma_write_info_free_async); - queue_work(svcrdma_wq, &info->wi_work); -} - /** * svc_rdma_write_chunk_release - Release Write chunk I/O resources * @rdma: controlling transport