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=-0.6 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,T_DKIM_INVALID autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id 5B99BC433EF for ; Fri, 15 Jun 2018 08:12:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0B929208B8 for ; Fri, 15 Jun 2018 08:12:34 +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="RVEx1zbh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0B929208B8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org 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 S1756018AbeFOIMd (ORCPT ); Fri, 15 Jun 2018 04:12:33 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:58682 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755847AbeFOIMc (ORCPT ); Fri, 15 Jun 2018 04:12:32 -0400 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=MWe+AXNnb/K85IU5quTuJ4mdg1eJtIwrkHg1jZwS5/Y=; b=RVEx1zbhrWlrSY2qiIzf03mRc FjmhO2XxqViZZ/34maHWIitu/YOP8ZKaVXbTGgnk4LXCPfSh6BUaFzTP538m2AJM3i+Zaid7pgKEr trXVgteUpS2HH5IrwIfIQL/TPEIDS7MYc3TGfNxTJEE4krE1JwSbOYI/ntre8JOEaNufoDZAkjJis r6eds0Eae1e0eUH45RUMNx4FA54NnDoXWsjiE45bobNVtvs5DKt9vpUE+d9x6XBJ2q2lfraWm5Zzf jfDJPjzf8CWhKKfTlAuH8RaKZrupd34XkUVdYVpGpjCB9kGdH1oZX6V9V4Iv8Hp73DeCyl9a4nASr 1XrzIucmg==; 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 1fTjqL-0005nb-IQ; Fri, 15 Jun 2018 08:12:25 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 020962029FA0D; Fri, 15 Jun 2018 10:12:23 +0200 (CEST) Date: Fri, 15 Jun 2018 10:12:23 +0200 From: Peter Zijlstra To: "Jin, Yao" Cc: acme@kernel.org, jolsa@kernel.org, mingo@redhat.com, alexander.shishkin@linux.intel.com, me@kylehuey.com, Linux-kernel@vger.kernel.org, vincent.weaver@maine.edu, will.deacon@arm.com, eranian@google.com, namhyung@kernel.org, ak@linux.intel.com, kan.liang@intel.com, yao.jin@intel.com Subject: Re: [PATCH v1 0/2] perf: Drop leaked kernel samples Message-ID: <20180615081223.GB2458@hirez.programming.kicks-ass.net> References: <1529057003-2212-1-git-send-email-yao.jin@linux.intel.com> <20180615074504.GA2458@hirez.programming.kicks-ass.net> <11958be5-dc05-611b-6839-f1f6903c7ca8@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <11958be5-dc05-611b-6839-f1f6903c7ca8@linux.intel.com> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 15, 2018 at 04:01:45PM +0800, Jin, Yao wrote: > Bring more overhead to kernel if we zero the bits considering the number of > leaked samples may be not too small? Keeping the samples at least allows you to know how many samples happened and such things. > And the skid information may be interesting (see example of hitting on > page_fault in previous mail). If we zero it, we will not know. If you throw them out the window you also don't know, do you?