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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 54373C32792 for ; Mon, 30 Sep 2019 15:12:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 32A0721855 for ; Mon, 30 Sep 2019 15:12:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731504AbfI3PMi (ORCPT ); Mon, 30 Sep 2019 11:12:38 -0400 Received: from mx2.suse.de ([195.135.220.15]:40412 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731276AbfI3PMi (ORCPT ); Mon, 30 Sep 2019 11:12:38 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 168C9AF7E; Mon, 30 Sep 2019 15:12:36 +0000 (UTC) Date: Mon, 30 Sep 2019 17:12:34 +0200 From: Michal =?iso-8859-1?Q?Koutn=FD?= To: Mina Almasry Cc: Tejun Heo , Mike Kravetz , Greg Thelen , David Rientjes , Shakeel Butt , shuah , linux-mm@kvack.org, Andrew Morton , Aneesh Kumar , khalid.aziz@oracle.com, cgroups@vger.kernel.org, open list , linux-kselftest@vger.kernel.org Subject: Re: [PATCH v5 0/7] hugetlb_cgroup: Add hugetlb_cgroup reservation limits Message-ID: <20190930151233.GH6694@blackbody.suse.cz> References: <20190919222421.27408-1-almasrymina@google.com> <3c73d2b7-f8d0-16bf-b0f0-86673c3e9ce3@oracle.com> <8f7db4f1-9c16-def5-79dc-d38d6b9d150e@oracle.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="YhFoJY/gx7awiIuK" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org --YhFoJY/gx7awiIuK Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hi. On Thu, Sep 26, 2019 at 05:55:29PM -0700, Mina Almasry wrote: > My guess is that a new controller needs to support cgroups-v2, which > is fine. But can a new controller also support v1? Or is there a > requirement that new controllers support *only* v2? I need whatever > solution here to work on v1. Here is my view of important criteria: 1) stability, v1 APIs and semantics should not be changed, 2) futureproofness, v1 uses should be convertible to v2 uses, 3) maintainability, the less (similar) code the better. And here is my braindump of some approaches: A) new controller, v2 only - 1) ok - 2) may be ok - 3) separate v1 and v2 implementations - exclusion must be ensured on hybrid hierarchies B) new controller, version oblivious (see e.g. pid) - 1) sort of ok - 2) partially ok - 3) two v1 implementations - exclusion must be ensured even on pure v1 hierarchies C) extending the existing controller, w/out v2 counterpart - 1) ok with workarounds (new option switching behavior) - 2) not ok - 3) likely OK D) extending the existing controller, with v2 counterpart - 1) ok with workarounds (new option switching behavior, see cpuset) - 2) may be ok - 3) likely OK AFAIU, the current patchset is variation of C). Personally, I think something like D) could work, I'm not convinced about A) and B) based on the breakdown above. But it may induce some other ideas. My two cents, Michal --YhFoJY/gx7awiIuK Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEEoQaUCWq8F2Id1tNia1+riC5qSgFAl2SG14ACgkQia1+riC5 qShedQ/8DyEdvjT0PcRMLE3EjsjDi32g8BDv8aIV1H1UVciQZIM+BFvPycHsjJ9N XwYn3bspedb10o6wm1Luj6LhXjVht5dglPSrmhTWp4E5YrLqP2AqKPt8p5ZL4pTq L64SrAHXo5qFq85CDnSQkFgYXmuPEkM9NCdLN3Dt30P1/zr6mrt0vhPbLNwJkgdT xsTp2UObM12TuEJxsnb2F6nirZLa6RHQ3utUjDZUsLbPOgnb+WbTgLyCNwHFnqUk bInSN/vrHcn52yYefxWuHW1VdXXV2vpjqcQG5CdYjXEzpKQxnysI+IiYxpv4kw6Q FQpT5nQtCVVr2EHj9LEsk9vgks2Hcfsb87psTIL0rxA4HvxiutPcDHBHqhcs/52o 2ozl8p7G0WXGYQ+bSeTBJ35O/qtTGibw1YELSkpVhG742SrzMj9SxdhtFO7dsdeY uk/HdATsAPl3kAX1fOhUSmIcnOL9ECAO0pgcRnmsyPdXEDUWwaiji0tK9Q0yP6Wu jnFTX3MY/Nq5FhJzZ3QYvCUxc1n1LgzW9STMUU5MuTN9NYXC4AlZnZhMqduDH5HK l0seBNntlNnaI4lQhbWl2OR0cXTDN88Nv2bF84LBI01F4N2D/NL97p69jCMYxgUx 5EiC89zRH0RUxb8RX+NeMG/OMd0qxTNFELjONXX1D5fpzLqg5Ao= =ksZu -----END PGP SIGNATURE----- --YhFoJY/gx7awiIuK--