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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EFF41C43217 for ; Thu, 5 May 2022 23:54:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347153AbiEEX6X (ORCPT ); Thu, 5 May 2022 19:58:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238237AbiEEX6U (ORCPT ); Thu, 5 May 2022 19:58:20 -0400 Received: from mail-vs1-xe2e.google.com (mail-vs1-xe2e.google.com [IPv6:2607:f8b0:4864:20::e2e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5862F60AA5 for ; Thu, 5 May 2022 16:54:39 -0700 (PDT) Received: by mail-vs1-xe2e.google.com with SMTP id u205so5705213vsu.6 for ; Thu, 05 May 2022 16:54:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=tDDyzRVab5pN0l0Oc9TAGru6/qJIRko7NAIbkOiJF8A=; b=r1hLylWIOOOhaGFz+p6F3AydVEizM2PBMopIl7xCwgCpXpdj2SokxxV2SHoaI7PsS5 O5XPHbELH3T7ucpExD9G9kVlFRitPY7R7wqnjKFPFLIxiMf35ksgPBUGvOAa8J2qSLnA QyTdGasRks2Hu/SE+misUqRIisf3JSGLfx/+ngOcXh4xDTDaEcERE/5fhgMDAaNmg9eE XxGq2KReyZ+PuXCPEUzSvCQVdKgX+qxpRhgSMBPttinWyGCEIuhX/kpStjsbylnebD2X vAkIk10ud0IVJn1anD+35kseqge1JuMc50aIHwAcrX8491ZfphZk/mlv0nA3ZBCz5Afe GC5w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=tDDyzRVab5pN0l0Oc9TAGru6/qJIRko7NAIbkOiJF8A=; b=KxCzbV0KkL6jvq7zK1XUSy8Ja2CwB8/xjPrT4vGOosHG6wYSNeWzScNaW+rchHfB1V s9YsoMUrfv9wY5YkCxPjssj2W/Iqf0zOt9iA2oYASs8soqLoGf/cVMvcaen3v2FyPt7z N1W+zvxZw0M9qsbCpkSK/TTgTKLdDwmcbwvie5kfGINeiCkYqK+/iqVPjMSSH0nf6/XR dzBj5rBNepNOK6xpC+MzH3b8XBV8Fs7MetCs7U4uYfAKQH6WmXbbjMRuMSwpRwx4JdO4 GyuECbOxUeaFD2XCSo5GvyUudBvZ8zEhTUPqZJ1qYVvH4xe5inl23O+x+giDFr5SO0LA Dn3A== X-Gm-Message-State: AOAM531wjlzD/kRNeytDPzSO+jrGDjmLAkLH+WC4gb2aX+0xOdnDe1E7 w/UolI0IXQK3HroqONCa3CFwxc5wsbCcmu7Y5kxK6A== X-Google-Smtp-Source: ABdhPJxopamlFqZOgSKVhG7nIetrG2PG7cgpRoI22LRBUGNQCpa8b8bZVtse6QuNZy6mGp6tZHSNhz6wiA/JWjuxyp0= X-Received: by 2002:a05:6102:c13:b0:32d:518f:feaf with SMTP id x19-20020a0561020c1300b0032d518ffeafmr174918vss.84.1651794878401; Thu, 05 May 2022 16:54:38 -0700 (PDT) MIME-Version: 1.0 References: <20220427160016.144237-1-hannes@cmpxchg.org> <20220427160016.144237-5-hannes@cmpxchg.org> In-Reply-To: From: Yu Zhao Date: Thu, 5 May 2022 16:54:02 -0700 Message-ID: Subject: Re: [PATCH 4/5] mm: zswap: add basic meminfo and vmstat coverage To: Suleiman Souhlal , Yang Shi Cc: Shakeel Butt , Johannes Weiner , Minchan Kim , Andrew Morton , Michal Hocko , Roman Gushchin , Seth Jennings , Dan Streetman , Linux MM , Cgroups , LKML , Kernel Team Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 5, 2022 at 3:25 PM Suleiman Souhlal wrote: > > On Fri, May 6, 2022 at 4:33 AM Shakeel Butt wrote: > > > > On Thu, Apr 28, 2022 at 9:54 AM Yang Shi wrote: > > > > > [...] > > > > Yes, we have some modifications to zswap to make it work without any > > > > backing real swap. Though there is a future plan to move to zram > > > > eventually. > > > > > > Interesting, if so why not just simply use zram? > > > > > > > Historical reasons. When we started trying out the zswap, I think zram > > was still in staging or not stable enough (Suleiman can give a better > > answer). > > One of the reasons we chose zswap instead of zram is that zswap can > reject pages. > Also, we wanted to have per-memcg pools, which zswap made much easier to do. Yes, it was a design choice. zswap was cache-like (tiering) and zram was storage-like (endpoint). Though nowadays the distinction is blurry. It had nothing to do with zram being in staging -- when we took zswap, it was out of the tree.