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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 70B76C433EF for ; Thu, 5 May 2022 23:54:40 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 08C636B0073; Thu, 5 May 2022 19:54:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 03B756B0074; Thu, 5 May 2022 19:54:39 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E1EE36B0075; Thu, 5 May 2022 19:54:39 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id D54B96B0073 for ; Thu, 5 May 2022 19:54:39 -0400 (EDT) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay12.hostedemail.com (Postfix) with ESMTP id AC419120C86 for ; Thu, 5 May 2022 23:54:39 +0000 (UTC) X-FDA: 79433346678.16.C8FAF59 Received: from mail-vs1-f46.google.com (mail-vs1-f46.google.com [209.85.217.46]) by imf09.hostedemail.com (Postfix) with ESMTP id 0B1BA14008A for ; Thu, 5 May 2022 23:54:32 +0000 (UTC) Received: by mail-vs1-f46.google.com with SMTP id q2so5702202vsr.5 for ; Thu, 05 May 2022 16:54:38 -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=rN41QoI9Pfev5EdnlTahrc/q4RAb5MfyJUsWaZXWmcClmTsnx71o51XQNvSOm51dVj m4BYEaE82GDG0ZPHYgj6lH4ZG7RD8JZISJ3j/kGOSJDIEmSspSITtO1W/wqLj5Bu+VpT 8fq8pC5+NYyAZUUKS8IlKSquahfSrxtOonkwmLKr0+VVnxWY6MiTCZQtVdt/gWHf9Vtb 4r7tw4WywEaFk43MCO38RZLoMxEB9CcIp27XLk190AQW4UPCO2QfvNjbryO0/7BATOTO Hx5OHwraKjWS3QrY4lQFf9eNMHwrFANkJJi+YirDC33TBN2E14qI5/z0Z6vlqW6GBAwG RmFg== X-Gm-Message-State: AOAM5308IWTlTUN1yeZLtodCLGX0e/PSvdjUV+/0Cza4WoSX+xayoEoe Ai3QQtFoZmt0jVjhcLtL0Rx+cv5LfObTSUqj+NUT9A== 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" X-Rspamd-Queue-Id: 0B1BA14008A X-Stat-Signature: yr14kkswwujbm6t5rpks1qnfq37huzd4 Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=r1hLylWI; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf09.hostedemail.com: domain of yuzhao@google.com designates 209.85.217.46 as permitted sender) smtp.mailfrom=yuzhao@google.com X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1651794872-452510 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000010, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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.