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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,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 31C74C43381 for ; Mon, 18 Feb 2019 20:40:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 00FBD20C01 for ; Mon, 18 Feb 2019 20:40:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="u9JWkSw3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729807AbfBRUk2 (ORCPT ); Mon, 18 Feb 2019 15:40:28 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:35410 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725844AbfBRUk1 (ORCPT ); Mon, 18 Feb 2019 15:40:27 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=D4KVafrIWO3hRL7wT1pFyqZZqP8UP6+r/2o6A4Cqn30=; b=u9JWkSw32M7Y0PECZWpQl5Rqb iF15GJPxMH/cTKJTSQTCyxrIgL1b4XQKjBxSe1KDOU0rVtgF3yJmtXaKBycEXRT8GG3G65CaONGCR Mc2HKG7e2XxXPq1Gl8Q+rMc7UBQno0+q4sI4GzxE4OpQthuvEG57xmZbnZXkPPSZ8RDsL5OKRDfYc E+bCxyrhsme+gBePf9I9oqacPbnObDKAMYpqYWtSEIqsROQ6tcqQbaMf0gp2xzgUQWO/fSvko6Nbn 4Ja8sbcrIgFasxD7CZXgNpJ0GqhuZjI+bINVIB8F6ZjO8Fif7HKI90HaqoPtrZHY8nsytRngvEgNZ DoZZZ9Myg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gvpiB-0004v8-24; Mon, 18 Feb 2019 20:40:23 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 42F5F201A4F68; Mon, 18 Feb 2019 21:40:20 +0100 (CET) Date: Mon, 18 Feb 2019 21:40:20 +0100 From: Peter Zijlstra To: Linus Torvalds Cc: Ingo Molnar , Thomas Gleixner , Paul Turner , Tim Chen , Linux List Kernel Mailing , subhra.mazumdar@oracle.com, =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , Kees Cook , kerrnel@google.com Subject: Re: [RFC][PATCH 00/16] sched: Core scheduling Message-ID: <20190218204020.GV32494@hirez.programming.kicks-ass.net> References: <20190218165620.383905466@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Mon, Feb 18, 2019 at 09:49:10AM -0800, Linus Torvalds wrote: > On Mon, Feb 18, 2019 at 9:40 AM Peter Zijlstra wrote: > > > > However; whichever way around you turn this cookie; it is expensive and nasty. > > Do you (or anybody else) have numbers for real loads? > > Because performance is all that matters. If performance is bad, then > it's pointless, since just turning off SMT is the answer. Not for these patches; they stopped crashing only yesterday and I cleaned them up and send them out. The previous version; which was more horrible; but L1TF complete, was between OK-ish and horrible depending on the number of VMEXITs a workload had. If there were close to no VMEXITs, it beat smt=off, if there were lots of VMEXITs it was far far worse. Supposedly hosting people try their very bestest to have no VMEXITs so it mostly works for them (with the obvious exception of single VCPU guests). It's just that people have been bugging me for this crap; and I figure I'd post it now that it's not exploding anymore and let others have at.