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=-6.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 DD71EC07E9A for ; Wed, 14 Jul 2021 13:22:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C6AC66128C for ; Wed, 14 Jul 2021 13:22:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239344AbhGNNY4 (ORCPT ); Wed, 14 Jul 2021 09:24:56 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:21308 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232007AbhGNNX4 (ORCPT ); Wed, 14 Jul 2021 09:23:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1626268864; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=+fntq9dxK/DsvMDb1vmj39FQnBcJ0Sqj0F7MADcjTnk=; b=bVncbu38tH9UfwNj8FBBG/XxFgOV2gr0EZEJUypARLyH+gittYt6httFi8OHN+hq6+vrnj 3KhRwXVLLutCE4bnbGJ8DFnHGiM8dpTJONP/OV+yH4p2ebvOUNL5l/iVDg8qko5aGWfpLP 5cb0z0aT7o/7/VEYAzFkAigsSXHhGzQ= Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-400-LphS1ktGPbKaFn7dDbu8Gg-1; Wed, 14 Jul 2021 09:21:03 -0400 X-MC-Unique: LphS1ktGPbKaFn7dDbu8Gg-1 Received: by mail-ed1-f69.google.com with SMTP id c21-20020aa7d6150000b02903ab03a06e86so1225832edr.14 for ; Wed, 14 Jul 2021 06:21:02 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=+fntq9dxK/DsvMDb1vmj39FQnBcJ0Sqj0F7MADcjTnk=; b=n/duvQl/H9jNM30jZAp29hP9P53SI3vRUZ/EmJGF+RvpdPbPi1pr0pA0rfVnlMAmlM c0cSMxRnTWfpef7CuImtIuLCO6vKbL2V/c1SPmaRLu8kCoJhtazruBnb38iOx4uCM7Pk +56G65/BCQ7k9nGxwMCGN7jmQZ69bD4zRCctE3soF+AaoljChgFyQTTSVzdd3ROTDJz2 uKxjs+sScsZ5RX8HEEa4D4FfhkstmIM47pcewHW6Mvmu5FI36trWpcNtNA5UsWGxXSKm ufOKzXZi/8GvGsUEbY8kPCLP3Irz8QxyE61L8xU/FdPkd8+ardMNQG8KzjE4UhZpYQB9 CJ3g== X-Gm-Message-State: AOAM533YNc666N8d7/bG0KdQp4CxyIR+zOhFDkt3/3zNOLXD29CIXBS0 6W05YgBjDg4/z+h4JFxpXXTSg21CPosmUNWzib006Q7qxNMTtWjBc1jQqP8dO5be/CNxCFLjsmS j3jgZFanwDjnBtStFxFnIP0Bj X-Received: by 2002:a05:6402:17d3:: with SMTP id s19mr13544049edy.49.1626268861893; Wed, 14 Jul 2021 06:21:01 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyL7BSCePriyxKihJPYAItdtydFUidngy/E8P+iCKdpMyGjTTXvx+4VpuJJqgrbrMXY5WRlJw== X-Received: by 2002:a05:6402:17d3:: with SMTP id s19mr13544026edy.49.1626268861714; Wed, 14 Jul 2021 06:21:01 -0700 (PDT) Received: from vitty.brq.redhat.com (g-server-2.ign.cz. [91.219.240.2]) by smtp.gmail.com with ESMTPSA id p26sm788024ejn.112.2021.07.14.06.21.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Jul 2021 06:21:01 -0700 (PDT) From: Vitaly Kuznetsov To: Juergen Gross Cc: Jonathan Corbet , Paolo Bonzini , Sean Christopherson , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , linux-kernel@vger.kernel.org, x86@kernel.org, linux-doc@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH 6/6] x86/kvm: add boot parameter for setting max number of vcpus per guest In-Reply-To: <62679c6a-2f23-c1d1-f54c-1872ec748965@suse.com> References: <20210701154105.23215-1-jgross@suse.com> <20210701154105.23215-7-jgross@suse.com> <87h7gx2lkt.fsf@vitty.brq.redhat.com> <1ddffb87-a6a2-eba3-3f34-cf606a2ecba2@suse.com> <878s292k75.fsf@vitty.brq.redhat.com> <62679c6a-2f23-c1d1-f54c-1872ec748965@suse.com> Date: Wed, 14 Jul 2021 15:21:00 +0200 Message-ID: <8735sh2fr7.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Juergen Gross writes: > On 14.07.21 13:45, Vitaly Kuznetsov wrote: > >> Personally, I'd vote for introducing a 'ratio' parameter then so >> generally users will only have to set 'kvm.max_vcpus'. > > Okay. > > Default '4' then? Or '2 ^ (topology_levels - 2)' (assuming a > topology_level of 3 on Intel: thread/core/socket and 4 on EPYC: > thread/core/package/socket). I'd suggest we default to '4' for both Intel and AMD as we haven't given up completely on cross-vendor VMs (running AMD VMs on Intel CPUs and vice versa). It would be great to leave a comment where the number comes from of course. -- Vitaly