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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 268ABC3A59D for ; Thu, 22 Aug 2019 09:06:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ECFF821655 for ; Thu, 22 Aug 2019 09:06:08 +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="H96MoQ+X" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732115AbfHVJGI (ORCPT ); Thu, 22 Aug 2019 05:06:08 -0400 Received: from merlin.infradead.org ([205.233.59.134]:55022 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727910AbfHVJGI (ORCPT ); Thu, 22 Aug 2019 05:06:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=jQUmhm+crCMl7aYhsmY917C2u3wYSGbnGiCkrOsABG0=; b=H96MoQ+Xd3KhAeEuhp3KuJohI 7ynuQoFB+FMMXI0yuJcBPGyPNWoozF3fDKL9kl4B1XlMv3+6HktRE1qRLl7vo2y5kWQsZ1DyZye2c D9kG9tcMcVvyCEkQ+xqenprcGbr2Gvn0PAaMxckZsZrBkOjWWIh522IzryqmQX0oBFf0K/llZ93O6 ZDU/ioNYP/VUNvq59utMpn18uDg7xZOFlRcstWcRz1zfQ9Ez0NQEKeBhW+jmRezsiZrZTxj3r+RT6 zHReVu6e3nCBZlm6teISKVXXZnYetDwGV4kJGAqQtH/SBfvLNvHDE5vEekVryI6QFRfDmLqGtuE0V KC4nhDu6Q==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1i0j2c-0000zc-VK; Thu, 22 Aug 2019 09:05:59 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 82957307145; Thu, 22 Aug 2019 11:05:23 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8000620A21FDF; Thu, 22 Aug 2019 11:05:55 +0200 (CEST) Date: Thu, 22 Aug 2019 11:05:55 +0200 From: Peter Zijlstra To: Song Liu Cc: Yonghong Song , Daniel Xu , "bpf@vger.kernel.org" , Andrii Nakryiko , "mingo@redhat.com" , "acme@kernel.org" , Alexei Starovoitov , "alexander.shishkin@linux.intel.com" , "jolsa@redhat.com" , "namhyung@kernel.org" , "linux-kernel@vger.kernel.org" , Kernel Team , Arnaldo Carvalho de Melo Subject: Re: [PATCH v3 bpf-next 1/4] tracing/probe: Add PERF_EVENT_IOC_QUERY_PROBE ioctl Message-ID: <20190822090555.GJ2349@hirez.programming.kicks-ass.net> References: <20190820144503.GV2332@hirez.programming.kicks-ass.net> <20190821110856.GB2349@hirez.programming.kicks-ass.net> <62874df3-cae0-36a1-357f-b59484459e52@fb.com> <20190821183155.GE2349@hirez.programming.kicks-ass.net> <5ecdcd72-255d-26d1-baf3-dc64498753c2@fb.com> <20190822074737.GG2349@hirez.programming.kicks-ass.net> 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: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, Aug 22, 2019 at 07:54:16AM +0000, Song Liu wrote: > Hi Peter, > > > On Aug 22, 2019, at 12:47 AM, Peter Zijlstra wrote: > > > > On Wed, Aug 21, 2019 at 06:43:49PM +0000, Yonghong Song wrote: > >> On 8/21/19 11:31 AM, Peter Zijlstra wrote: > > > >>> So extending PERF_RECORD_LOST doesn't work. But PERF_FORMAT_LOST might > >>> still work fine; but you get to implement it for all software events. > >> > >> Could you give more specifics about PERF_FORMAT_LOST? Googling > >> "PERF_FORMAT_LOST" only yields two emails which we are discussing here :-( > > > > Look at what the other PERF_FORMAT_ flags do? Basically it is adding a > > field to the read(2) output. > > Do we need to implement PERF_FORMAT_LOST for all software events? If user > space asks for PERF_FORMAT_LOST for events that do not support it, can we > just fail sys_perf_event_open()? It really shouldn't be hard; and I'm failing to see why kprobes are special.