From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8D658C2D0A3 for ; Tue, 3 Nov 2020 20:42:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4EF9A223C6 for ; Tue, 3 Nov 2020 20:42:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604436150; bh=zWCLfp4h721j+VW/7uhVawdS9abHhVhI1Vy7IztB9dY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=rBmOlee1SwtJWVweWB3kzbtCMFjMdA8ljl1Zz+Ut98UpX1A2I1/6zUCAKmB4pJQfu JUtVlLvTxu7bpsIXLPexZ4wq9ZroPuzKUGkOzK4kXAg/rnMNUyA3EV6aYr9owXQE9H WQ3kzDej/ViiTHBeYd+bpMyr0cHwlbYmXyfpX1+c= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730528AbgKCUm3 (ORCPT ); Tue, 3 Nov 2020 15:42:29 -0500 Received: from mail.kernel.org ([198.145.29.99]:54468 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730487AbgKCUmS (ORCPT ); Tue, 3 Nov 2020 15:42:18 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AD15922226; Tue, 3 Nov 2020 20:42:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604436138; bh=zWCLfp4h721j+VW/7uhVawdS9abHhVhI1Vy7IztB9dY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Zs+4jsvou4Yeu/L6fpy5MzDjCyTVrDbeT1aHEkSrIj/g3aZ787KeOP49C+AEfgLnz 3E5o/bxEvX89KB3TV7xPnRn8jfmsXflAf5Cvv8E67/0eauyZMlNS8j4OSS299KX/3m oSb+3Fm3Ke6/LgI9RaMsoRx6MDR7r1W35aRGV6v8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chuck Lever , Anna Schumaker , Sasha Levin Subject: [PATCH 5.9 119/391] SUNRPC: Mitigate cond_resched() in xprt_transmit() Date: Tue, 3 Nov 2020 21:32:50 +0100 Message-Id: <20201103203354.853516171@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201103203348.153465465@linuxfoundation.org> References: <20201103203348.153465465@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Chuck Lever [ Upstream commit 6f9f17287e78e5049931af2037b15b26d134a32a ] The original purpose of this expensive call is to prevent a long queue of requests from blocking other work. The cond_resched() call is unnecessary after just a single send operation. For longer queues, instead of invoking the kernel scheduler, simply release the transport send lock and return to the RPC scheduler. Signed-off-by: Chuck Lever Signed-off-by: Anna Schumaker Signed-off-by: Sasha Levin --- net/sunrpc/xprt.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index 5a8e47bbfb9f4..13fbc2dd4196a 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -1520,10 +1520,13 @@ xprt_transmit(struct rpc_task *task) { struct rpc_rqst *next, *req = task->tk_rqstp; struct rpc_xprt *xprt = req->rq_xprt; - int status; + int counter, status; spin_lock(&xprt->queue_lock); + counter = 0; while (!list_empty(&xprt->xmit_queue)) { + if (++counter == 20) + break; next = list_first_entry(&xprt->xmit_queue, struct rpc_rqst, rq_xmit); xprt_pin_rqst(next); @@ -1531,7 +1534,6 @@ xprt_transmit(struct rpc_task *task) status = xprt_request_transmit(next, task); if (status == -EBADMSG && next != req) status = 0; - cond_resched(); spin_lock(&xprt->queue_lock); xprt_unpin_rqst(next); if (status == 0) { -- 2.27.0