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=-2.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 A5E92C10F13 for ; Thu, 11 Apr 2019 06:23:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 708092082E for ; Thu, 11 Apr 2019 06:23:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Ui/9frl7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726121AbfDKGX4 (ORCPT ); Thu, 11 Apr 2019 02:23:56 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:60370 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726104AbfDKGX4 (ORCPT ); Thu, 11 Apr 2019 02:23:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=GyLiEuwmSDvgfgDVNlQrycxouzuZDlkHOzeNnN5hMEA=; b=Ui/9frl7lefnxv3yEzCcxU/ib BzDCZdi+LB9oHTZTQ07CTaULZs5ikgEs1/mv0opJWgc9T5Ii+W+baCDk8kdnZAdMqi+IIK0w6Ad3Y m7tC0k2c1RQuwpkcGQAiyOP98Gl3R5b6p09v//+/QAguC467s8uRgCc6Vd9bIKgZuNhCPz/df8sIK eRgDsiw5ps01UEOAqs4nU/BQSRUI9cXM7QUwDJ5Zpxr/ElRgwWEE5Xm7o0bg8K5waMjEsvJXe+6UV cxOUqYqzKLGCrnvTSLmmjGB+cJjQIKDTh21AJyUuiHXomyKBQH2U8JMILFAGWzpkU8+q27KKT3X/m u9bclQGiA==; Received: from 089144214194.atnat0023.highway.a1.net ([89.144.214.194] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hET7q-0005LL-EY; Thu, 11 Apr 2019 06:23:54 +0000 From: Christoph Hellwig To: Jens Axboe Cc: Ming Lei , linux-block@vger.kernel.org Subject: avoid calling nth_page in the block I/O path v2 Date: Thu, 11 Apr 2019 08:23:26 +0200 Message-Id: <20190411062331.27800-1-hch@lst.de> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hi Jens, you complained about the overhead of calling nth_page in the multipage bio_vec enabled I/O path a while ago. While I can't really reproduce the numbers on my (slower) hardware we could avoid the nth_page calls pretty easily with a few tweaks. Can you take a look at this series? Changes since v1: - remove a spurious variable initialization