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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 DFBEEC43142 for ; Fri, 22 Jun 2018 09:50:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A2ECD23FB2 for ; Fri, 22 Jun 2018 09:50:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A2ECD23FB2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754172AbeFVJuv (ORCPT ); Fri, 22 Jun 2018 05:50:51 -0400 Received: from verein.lst.de ([213.95.11.211]:55640 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751242AbeFVJuu (ORCPT ); Fri, 22 Jun 2018 05:50:50 -0400 Received: by newverein.lst.de (Postfix, from userid 2407) id D8C9668E45; Fri, 22 Jun 2018 12:00:14 +0200 (CEST) Date: Fri, 22 Jun 2018 12:00:14 +0200 From: Christoph Hellwig To: Linus Torvalds Cc: kernel test robot , Al Viro , Christoph Hellwig , Greg Kroah-Hartman , "Darrick J. Wong" , Linux Kernel Mailing List , LKP Subject: Re: [lkp-robot] [fs] 3deb642f0d: will-it-scale.per_process_ops -8.8% regression Message-ID: <20180622100014.GA12425@lst.de> References: <20180622082752.GX11011@yexl-desktop> <20180622095608.GA12263@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180622095608.GA12263@lst.de> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org And a version with select() also covered: --- >From 317159003ae28113cf759c632b161fb39192fe3c Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Fri, 22 Jun 2018 11:36:26 +0200 Subject: fs: optimize away ->_qproc indirection for poll_mask based polling Signed-off-by: Christoph Hellwig --- fs/select.c | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) diff --git a/fs/select.c b/fs/select.c index bc3cc0f98896..2c9d81892509 100644 --- a/fs/select.c +++ b/fs/select.c @@ -528,6 +528,24 @@ static int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time) wait_key_set(wait, in, out, bit, busy_flag); mask = vfs_poll(f.file, wait); + if (f.file->f_op->poll) { + mask = f.file->f_op->poll(f.file, wait); + } else if (file_has_poll_mask(f.file)) { + struct wait_queue_head *head; + + head = f.file->f_op->get_poll_head(f.file, wait->_key); + if (!head) { + mask = DEFAULT_POLLMASK; + } else if (IS_ERR(head)) { + mask = EPOLLERR; + } else { + if (wait->_qproc) + __pollwait(f.file, head, wait); + mask = f.file->f_op->poll_mask(f.file, wait->_key); + } + } else { + mask = DEFAULT_POLLMASK; + } fdput(f); if ((mask & POLLIN_SET) && (in & bit)) { @@ -845,7 +863,25 @@ static inline __poll_t do_pollfd(struct pollfd *pollfd, poll_table *pwait, /* userland u16 ->events contains POLL... bitmap */ filter = demangle_poll(pollfd->events) | EPOLLERR | EPOLLHUP; pwait->_key = filter | busy_flag; - mask = vfs_poll(f.file, pwait); + if (f.file->f_op->poll) { + mask = f.file->f_op->poll(f.file, pwait); + } else if (file_has_poll_mask(f.file)) { + struct wait_queue_head *head; + + head = f.file->f_op->get_poll_head(f.file, pwait->_key); + if (!head) { + mask = DEFAULT_POLLMASK; + } else if (IS_ERR(head)) { + mask = EPOLLERR; + } else { + if (pwait->_qproc) + __pollwait(f.file, head, pwait); + mask = f.file->f_op->poll_mask(f.file, pwait->_key); + } + } else { + mask = DEFAULT_POLLMASK; + } + if (mask & busy_flag) *can_busy_poll = true; mask &= filter; /* Mask out unneeded events. */ -- 2.17.1