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=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 A028BC433E6 for ; Thu, 18 Feb 2021 19:14:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4D29D64EB9 for ; Thu, 18 Feb 2021 19:14:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230431AbhBRTNy (ORCPT ); Thu, 18 Feb 2021 14:13:54 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:21103 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234601AbhBRRsk (ORCPT ); Thu, 18 Feb 2021 12:48:40 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1613670431; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Vh8JVeAq553dnjUjXxpSp+/x6fHtJkixwlI1e+/bfY8=; b=RqkATTCPSeb2gmGwoVHNHMlg3AkybgX2FvMGHiylUP5xD09ZQ7zHPKMzsqZxZ9EZg5Vtum MgQf8Mx/bMnwHRi0RtVkY/jE0/MT7ZAddj6DU98C0X39/2LrZqSBZ5w7Dyb2ojxiIdh+sP 99WeNUegsnNW/3Tyn6/2BPOPr7n5BKk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-348-qum9-M-dOJ-dh4Cpmuan6A-1; Thu, 18 Feb 2021 12:47:10 -0500 X-MC-Unique: qum9-M-dOJ-dh4Cpmuan6A-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C51CF107ACF4; Thu, 18 Feb 2021 17:47:07 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-119-68.rdu2.redhat.com [10.10.119.68]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4C64060877; Thu, 18 Feb 2021 17:47:01 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20210217161358.GM2858050@casper.infradead.org> References: <20210217161358.GM2858050@casper.infradead.org> <161340385320.1303470.2392622971006879777.stgit@warthog.procyon.org.uk> <161340389201.1303470.14353807284546854878.stgit@warthog.procyon.org.uk> To: Matthew Wilcox Cc: dhowells@redhat.com, Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet , Alexander Viro , Christoph Hellwig , linux-mm@kvack.org, linux-cachefs@redhat.com, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, Jeff Layton , David Wysochanski , linux-kernel@vger.kernel.org Subject: Re: [PATCH 03/33] mm: Implement readahead_control pageset expansion MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2083367.1613670420.1@warthog.procyon.org.uk> Date: Thu, 18 Feb 2021 17:47:00 +0000 Message-ID: <2083368.1613670420@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org Matthew Wilcox wrote: > So readahead_expand() needs to adjust the file's f_ra so that when the > application gets to 64kB, it kicks off the readahead of 4MB-8MB chunk (and > then when we get to 4MB+256kB, it kicks off the readahead of 8MB-12MB, > and so on). Ummm... Two questions: Firstly, how do I do that? Set ->async_size? And to what? The expansion could be 2MB from a ceph stripe, 256k from the cache. Just to add to the fun, the leading edge of the window might also be rounded downwards and the RA trigger could be before where the app is going to start reading. Secondly, what happens if, say, a 4MB read is covered by a single 4MB THP? David