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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 7A2BCC2BB1D for ; Fri, 13 Mar 2020 12:01:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 50FDC206FA for ; Fri, 13 Mar 2020 12:01:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=firstfloor.org header.i=@firstfloor.org header.b="jmVephLy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726664AbgCMMBN (ORCPT ); Fri, 13 Mar 2020 08:01:13 -0400 Received: from one.firstfloor.org ([193.170.194.197]:40168 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726591AbgCMMBM (ORCPT ); Fri, 13 Mar 2020 08:01:12 -0400 X-Greylist: delayed 606 seconds by postgrey-1.27 at vger.kernel.org; Fri, 13 Mar 2020 08:01:12 EDT Received: by one.firstfloor.org (Postfix, from userid 503) id AB0A08684B; Fri, 13 Mar 2020 12:51:02 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=firstfloor.org; s=mail; t=1584100262; bh=n7ebr8CIADsM9tj3H3JRlE7EP41LvIJXYOqe5sj5lqQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jmVephLyA1jYljk7iIclfJA1dr9azRpru+nJgTyJckKMaG8CBSSnfRdV/yjUxcdQz 6bFxkMnPz2ufG+StfF9dEqD7RCgkx2j06wqVbIVd12U65FIXqpRRtRggV2V6PByZVx 4r0N/WpnBlArZuov1h66MTDtZmvJBCY3mbu8W/58= Date: Fri, 13 Mar 2020 04:51:02 -0700 From: Andi Kleen To: Andy Lutomirski Cc: Andi Kleen , x86@kernel.org, linux-kernel@vger.kernel.org, Andi Kleen Subject: Re: [PATCH] x86: Add trace points to (nearly) all vectors Message-ID: <20200313115100.3gdbfxkplrbe6wvy@two.firstfloor.org> References: <20200312231916.132753-1-andi@firstfloor.org> <742AF79F-BAE4-4E6C-944D-10C3E6F66CD0@amacapital.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <742AF79F-BAE4-4E6C-944D-10C3E6F66CD0@amacapital.net> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 12, 2020 at 04:39:04PM -0700, Andy Lutomirski wrote: > > > On Mar 12, 2020, at 4:19 PM, Andi Kleen wrote: > > > > From: Andi Kleen > > > > In some scenarios it can be useful to count or trace every kernel > > entry. > > Can you elaborate? What problem does this solve? So that we know how often or where kernel entries happen, how long every kernel execution is, and also can do an accurate break down. > > > Most entry paths are covered by trace points already, > > but some of the more obscure entry points do not have > > trace points. > > > > The most common uncovered one was KVM async page fault. > > NAK. This path is going away. Okay. Can you provide details? When will it go away? Anyways KVM async is just one case, my patch covers lots of other cases too. Even if KVM async goes away it still makes sense for the other entry points and can be easily rebased (just drop that hunk) -Andi