From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 2A1F16B0268 for ; Tue, 13 Mar 2018 10:18:19 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id s25so7516981pfh.9 for ; Tue, 13 Mar 2018 07:18:19 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id m5sor83646pgd.171.2018.03.13.07.18.17 for (Google Transport Security); Tue, 13 Mar 2018 07:18:17 -0700 (PDT) Date: Tue, 13 Mar 2018 23:18:13 +0900 From: Sergey Senozhatsky Subject: Re: [PATCHv2 2/2] zram: drop max_zpage_size and use zs_huge_class_size() Message-ID: <20180313141813.GA741@tigerII.localdomain> References: <20180306070639.7389-1-sergey.senozhatsky@gmail.com> <20180306070639.7389-3-sergey.senozhatsky@gmail.com> <20180313090249.GA240650@rodete-desktop-imager.corp.google.com> <20180313102437.GA5114@jagdpanzerIV> <20180313135815.GA96381@rodete-laptop-imager.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180313135815.GA96381@rodete-laptop-imager.corp.google.com> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Sergey Senozhatsky , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Sergey Senozhatsky , Mike Rapoport On (03/13/18 22:58), Minchan Kim wrote: > > > If it is static, we can do this in zram_init? I believe it's more readable in that > > > it's never changed betweens zram instances. > > > > We need to have at least one pool, because pool decides where the > > watermark is. At zram_init() stage we don't have a pool yet. We > > zs_create_pool() in zram_meta_alloc() so that's why I put > > zs_huge_class_size() there. I'm not in love with it, but that's > > the only place where we can have it. > > Fair enough. Then what happens if client calls zs_huge_class_size > without creating zs_create_pool? Will receive 0. One of the version was returning SIZE_MAX in such case. size_t zs_huge_class_size(void) { + if (unlikely(!huge_class_size)) + return SIZE_MAX; return huge_class_size; } > I think we should make zs_huge_class_size has a zs_pool as argument. Can do, but the param will be unused. May be we can do something like below instead: size_t zs_huge_class_size(void) { + if (unlikely(!huge_class_size)) + return 3 * PAGE_SIZE / 4; return huge_class_size; } Should do no harm (unless I'm missing something). -ss