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=-7.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 C9429C4740A for ; Tue, 10 Sep 2019 14:27:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9981120863 for ; Tue, 10 Sep 2019 14:27:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=digitalocean.com header.i=@digitalocean.com header.b="BjwE/NLn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387570AbfIJO1b (ORCPT ); Tue, 10 Sep 2019 10:27:31 -0400 Received: from mail-wr1-f65.google.com ([209.85.221.65]:36168 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726066AbfIJO1b (ORCPT ); Tue, 10 Sep 2019 10:27:31 -0400 Received: by mail-wr1-f65.google.com with SMTP id y19so20711496wrd.3 for ; Tue, 10 Sep 2019 07:27:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digitalocean.com; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=svTfK8XVs7zcozaB1slOaxRqDQ/z/h8slzAfLwekH/0=; b=BjwE/NLnb5Cq/OR3pqpew/QLm3vmNoHfIfpotJzLcmLzNArKzgt/lsD5QdvF9yE+HC clUWKDeU6jN8CHM3yG1dq84pdttJ01xchYNaIA9AFUTYpFC+UwH0fv/6rH+rkJMbjQDs aRsVIDEc4nWtXEdzKHuVahH0vylOq7Eggibc0= 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=svTfK8XVs7zcozaB1slOaxRqDQ/z/h8slzAfLwekH/0=; b=n70zRKScW0MbLrhe3oHJGVliACVrvtkEvUzLRYsQXP+5dG9JL3iSsj57Y5DxZWsoJ6 SRJNwX6WW/XXMItbwYd7mV8gUqx0efIEBZElRY5lTuP+wW7XSiS0o6BLQKdlPrqtQm32 Wwk5JXd+sXPzTUHgMwYdo9bXw0/cp70YHhwLj3hyM6cuFZgjIEtL1YXg4+zFKRVTNjzL dQ/ViN7Y6uuFo1lClcCNwJjz2z1cEpvSHMKM5w8Mv8R4aJCpNJRnGLP0TDLpjy5bITJW m+HR77Tdtn3jLE6gYngsNgv17uMWGaM/c/ex7bWXzVoM456B8m1dAWrd4BqF/X9A2zaI u11w== X-Gm-Message-State: APjAAAXW4k7huTvlVPiRxqXooclgdXwOIdYDkpxgKaOxqWRPKis9nGbO 3DuMzBjVQRCc/1Y4ve3huZ1KOQ== X-Google-Smtp-Source: APXvYqwMWJpaNy5fVNNj4cuTfglviaBc1H7tNSSdaqBDZhSBk1b00BQ5392WE1asafhKj3I3z333Wg== X-Received: by 2002:a5d:5642:: with SMTP id j2mr17795069wrw.345.1568125649269; Tue, 10 Sep 2019 07:27:29 -0700 (PDT) Received: from sinkpad ([148.69.85.38]) by smtp.gmail.com with ESMTPSA id v7sm15915206wru.87.2019.09.10.07.27.27 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 10 Sep 2019 07:27:28 -0700 (PDT) Date: Tue, 10 Sep 2019 10:27:17 -0400 From: Julien Desfossez To: Peter Zijlstra Cc: Phil Auld , Matthew Garrett , Vineeth Remanan Pillai , Nishanth Aravamudan , Tim Chen , mingo@kernel.org, tglx@linutronix.de, pjt@google.com, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, subhra.mazumdar@oracle.com, fweisbec@gmail.com, keescook@chromium.org, kerrnel@google.com, Aaron Lu , Aubrey Li , Valentin Schneider , Mel Gorman , Pawan Gupta , Paolo Bonzini Subject: Re: [RFC PATCH v3 00/16] Core scheduling v3 Message-ID: <20190910142717.GA1855@sinkpad> References: <20190827211417.snpwgnhsu5t6u52y@srcf.ucam.org> <20190827215035.GH2332@hirez.programming.kicks-ass.net> <20190828153033.GA15512@pauld.bos.csb> <20190828160114.GE17205@worktop.programming.kicks-ass.net> <20190829143050.GA7262@pauld.bos.csb> <20190829143821.GX2369@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190829143821.GX2369@hirez.programming.kicks-ass.net> X-Mailer: Mutt 1.9.4 (2018-02-28) User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29-Aug-2019 04:38:21 PM, Peter Zijlstra wrote: > On Thu, Aug 29, 2019 at 10:30:51AM -0400, Phil Auld wrote: > > I think, though, that you were basically agreeing with me that the current > > core scheduler does not close the holes, or am I reading that wrong. > > Agreed; the missing bits for L1TF are ugly but doable (I've actually > done them before, Tim has that _somewhere_), but I've not seen a > 'workable' solution for MDS yet. Following the discussion we had yesterday at LPC, after we have agreed on a solution for fixing the current fairness issue, we will post the v4. We will then work on prototyping the other synchronisation points (syscalls, interrupts and VMEXIT) to evaluate the overhead in various use-cases. Depending on the use-case, we know the performance overhead maybe heavier than just disabling SMT, but the benchmarks we have seen so far indicate that there are valid cases for core scheduling. Core scheduling will continue to be unused by default, but with it, we will have the option to tune the system to be both secure and faster than disabling SMT for those cases. Thanks, Julien P.S: I think the branch that contains the VMEXIT handling is here https://github.com/pdxChen/gang/commits/sched_1.23-base