From patchwork Mon Nov 13 13:42:59 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 13453993 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79F6FC4167B for ; Mon, 13 Nov 2023 13:43:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231408AbjKMNnE (ORCPT ); Mon, 13 Nov 2023 08:43:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33052 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231395AbjKMNnD (ORCPT ); Mon, 13 Nov 2023 08:43:03 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9DB7918B; Mon, 13 Nov 2023 05:43:00 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 035EDC433C9; Mon, 13 Nov 2023 13:42:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699882980; bh=lG5EYDtZnt2X+DiALFLYeV+KP/ShKxTW+QClyREU06I=; h=Subject:From:To:Cc:Date:From; b=iSI9PNnhmrIS9Z/dWBs6uHf5gS0+2vh6xrCU3DXAiWfCrjpfFCUMgDqjctf3hx2ls EOC/mdEW3yfTQOel7WuoCdf2yaSQiQo1W7LEJTRV4YvdX+VNoZH6DVhGGR+Ojwpo4q WFYCt5sg912NlIJtnQgg7nT4SyrXYwOU1CjFrzNKG612oKLr1lAp8RL4ga8es2ZIHB jkM74mvRGxt8n1wJMlUzMg4hsPg6ioutJKvmrhmX/BpZRvc2t41bdb1pRyFoThDxfV /cmvwFOdGQZanf62PRS6dSd2l2b+EMeH6hcfAaZtXqO6TlvUkkkW2zcqehsJB+9HKV U7HpoxL2g90KA== Subject: [PATCH v1 0/7] Switch NFS server CQs to use soft IRQ From: Chuck Lever To: linux-nfs@vger.kernel.org, linux-rdma@vger.kernel.org Cc: tom@talpey.com Date: Mon, 13 Nov 2023 08:42:59 -0500 Message-ID: <169988267843.6417.17927133323277523958.stgit@bazille.1015granger.net> User-Agent: StGit/1.5 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org I've found that using the ib_comp_wq for completion queues can add microseconds of latency in the average case and extend tail latencies significantly. Now that we've shaved a bunch of work out of the server's completion handlers, it should be safe to go back to using soft IRQ rather than ib_comp_wq, in order to gain better RTT latencies. --- Chuck Lever (7): svcrdma: Eliminate allocation of recv_ctxt objects in backchannel svcrdma: Clean up use of rdma->sc_pd->device in Receive paths svcrdma: Pre-allocate svc_rdma_recv_ctxt objects svcrdma: Switch Receive CQ to soft IRQ svcrdma: Clean up use of rdma->sc_pd->device svcrdma: Move the svcxprt_rdma::sc_pd field svcrdma: Move Send CQ to SOFTIRQ context include/linux/sunrpc/svc_rdma.h | 6 +-- net/sunrpc/xprtrdma/svc_rdma_backchannel.c | 11 ++-- net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 53 +++++++++++-------- net/sunrpc/xprtrdma/svc_rdma_rw.c | 4 +- net/sunrpc/xprtrdma/svc_rdma_sendto.c | 59 ++++++++++++---------- net/sunrpc/xprtrdma/svc_rdma_transport.c | 6 +-- 6 files changed, 75 insertions(+), 64 deletions(-) -- Chuck Lever