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=-4.1 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 91720C433E2 for ; Tue, 1 Sep 2020 19:44:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C5C02071B for ; Tue, 1 Sep 2020 19:44:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="K+VeHmUM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731913AbgIAToU (ORCPT ); Tue, 1 Sep 2020 15:44:20 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:43164 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726936AbgIAToU (ORCPT ); Tue, 1 Sep 2020 15:44:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1598989458; 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=nTHlq3Kl2GCIO7zccVhN6JeQ5RlCQEu/xPuuaep77Qk=; b=K+VeHmUMuGySv/GBtZ5hngff1skKlnluIGzkGzbgyLtQf7aBO8rcLqvPPRjSvFMczFB2hC EBg45NCQ/gsXuVtQLuGRV54M3PORZjHwnfUnAdRgvlqltQX1ZCL+lSGbeut8Lcal9rioxM H5Cf12h4yzLtsaqjQHCeyWrNEHz7lx8= 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-402-j-YWKZGfMaSROuVIV8aAKg-1; Tue, 01 Sep 2020 15:44:17 -0400 X-MC-Unique: j-YWKZGfMaSROuVIV8aAKg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 247FE425D1; Tue, 1 Sep 2020 19:44:16 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-113-231.rdu2.redhat.com [10.10.113.231]) by smtp.corp.redhat.com (Postfix) with ESMTP id 25FEC78B29; Tue, 1 Sep 2020 19:44:15 +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: <20200901164827.GQ14765@casper.infradead.org> References: <20200901164827.GQ14765@casper.infradead.org> <159897769535.405783.17587409235571100774.stgit@warthog.procyon.org.uk> To: Matthew Wilcox Cc: dhowells@redhat.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 0/7] mm: Make more use of readahead_control MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <423538.1598989454.1@warthog.procyon.org.uk> Date: Tue, 01 Sep 2020 20:44:14 +0100 Message-ID: <423539.1598989454@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Matthew Wilcox wrote: > > Note that I've been > > passing the number of pages to read in rac->_nr_pages, and then saving it > > and changing it certain points, e.g. page_cache_readahead_unbounded(). > > I do not like this. You're essentially mutating the meaning of _nr_pages > as the ractl moves down the stack, and that's going to lead to bugs. > I'd keep it as a separate argument. The meaning isn't specified in linux/pagemap.h. Can you adjust the comments on the struct and on readahead_count() to make it more clear what the value represents? Thanks, David