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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham 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 13947C433F4 for ; Thu, 20 Sep 2018 22:14:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 89A8F21534 for ; Thu, 20 Sep 2018 22:14:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="fWA7g56+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 89A8F21534 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725855AbeIUEAc (ORCPT ); Fri, 21 Sep 2018 00:00:32 -0400 Received: from mail-lf1-f68.google.com ([209.85.167.68]:35517 "EHLO mail-lf1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725759AbeIUEAb (ORCPT ); Fri, 21 Sep 2018 00:00:31 -0400 Received: by mail-lf1-f68.google.com with SMTP id x20-v6so9767796lfg.2; Thu, 20 Sep 2018 15:14:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=Z770HlOYnuiuFaHvQ7YcAaglZJGe3WPohVkcbEsuZj8=; b=fWA7g56+dE/Q2Oe0epHkEsTiY9EMGcf+zL72gsAslRb1M5ee1o//C5htGdSeF34uNY OPCXA5ycGxDBB2cnWzG9+PKMN/fXA6/mGdRQ7gckZ8lWSENZMwke+FUB+OWNEAtUw8hd Ic4M2/GeJU33BQrYRvDgKNqqSa6vYisND7ClJ7RTx75LWIIE5w3sYAu8UHVH3nK/Ykdl kbPUPcMJqlSjdaVH8vqHPiE7MlFC20SXiNPmVINTKumpg27c769VKdHhFF20wAhw/iwu GsyQzNvLdjRj+hL27f7YygDVg2Ird6k6IPdj/QUkFyZk0PzVUAbHXwx/sHK0WWQhjKxr 3E6g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=Z770HlOYnuiuFaHvQ7YcAaglZJGe3WPohVkcbEsuZj8=; b=TS/TuXRruVKO4KQibkhhENQ8SLqdTXO8VJPHwP8k2vugti9ftobezCoSccqyyqgDTX GnyxBg9NI9jjLepYPaquJnR2NlaW78vjyh7ctMCwvWThlfclH7Z7yLL8Pg7dTtmCPwwZ A7rySEOTJyZtc6hCC8xIyVeQ0NuXK69+7gY82XWvQWR1XdUJT4swPoBMHToB8xkO/KnV hnUHmyK183IRKSgFb0XptOwENxhcMTBxgPMSw5d2LL+H9BGiV/pqDlJ2EjJ0nR/woUjM nbOg1vqaqarx+x2w2imkodvab8l82XHgp//Rc5rYFDhW+IDWBZT1tibGq6UPYSBsIcuG BWIA== X-Gm-Message-State: APzg51AKrjTe28cfcox62F2yx2wzx2odq1HRdaqEc8ZB9hzgwBsSjXKr IBNXrfXqLfcrVxUO9w94SHw= X-Google-Smtp-Source: ANB0VdYxLGc8hbaomQ1RDPzf2t2X33+yNziG9R5lPvmQn/O+DbTDP9r+c18HRG/eQ0w8UEuMZNRCJQ== X-Received: by 2002:a19:f00a:: with SMTP id p10-v6mr10028357lfc.43.1537481690022; Thu, 20 Sep 2018 15:14:50 -0700 (PDT) Received: from uranus.localdomain ([5.18.102.224]) by smtp.gmail.com with ESMTPSA id y16-v6sm4684450lje.30.2018.09.20.15.14.49 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 20 Sep 2018 15:14:49 -0700 (PDT) Received: by uranus.localdomain (Postfix, from userid 1000) id C7AE6460674; Fri, 21 Sep 2018 01:14:48 +0300 (MSK) Date: Fri, 21 Sep 2018 01:14:48 +0300 From: Cyrill Gorcunov To: Cyrill Gorcunov Cc: Dmitry Safonov , linux-kernel@vger.kernel.org, Dmitry Safonov <0x7f454c46@gmail.com>, Andrei Vagin , Adrian Reber , Andy Lutomirski , Christian Brauner , "Eric W. Biederman" , "H. Peter Anvin" , Ingo Molnar , Jeff Dike , Oleg Nesterov , Pavel Emelyanov , Shuah Khan , Thomas Gleixner , containers@lists.linux-foundation.org, criu@openvz.org, linux-api@vger.kernel.org, x86@kernel.org Subject: Re: [RFC 02/20] timens: Add timens_offsets Message-ID: <20180920221448.GE20786@uranus> References: <20180919205037.9574-1-dima@arista.com> <20180919205037.9574-3-dima@arista.com> <20180920184510.GC20786@uranus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180920184510.GC20786@uranus> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 20, 2018 at 09:45:10PM +0300, Cyrill Gorcunov wrote: > On Wed, Sep 19, 2018 at 09:50:19PM +0100, Dmitry Safonov wrote: > > From: Andrei Vagin > > > > Introduce offsets for time namespace. They will contain adjustment > > needed to convert clocks to/from host's. > > > > Allocate one page for each time namespace that will be premapped into > > userspace with vvar pages. > > Is not it too much?! The whole page per each clone(new-time-ns) call. > Moreover everytime it is get explicitly zeroifyed. Don't get me wrong, > maybe I miss something obvious, but additional 4K per process, guys :) After being talking to Andrew I think there is no better option though. If syscalls would be free of course we could use them instead but this vdso stuff, sigh. I thouhgh about modifying vdso code so it would carry refs inside (or adding some section into elf loader kernel code), but all this would simply mess the code. Thus this 4K per namespace seems to be acceptable trade off.