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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 6918BC3A59E for ; Wed, 21 Aug 2019 20:04:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3B15D23403 for ; Wed, 21 Aug 2019 20:04:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Qb4/QdgA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730319AbfHUUEz (ORCPT ); Wed, 21 Aug 2019 16:04:55 -0400 Received: from mail-qk1-f194.google.com ([209.85.222.194]:36757 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730101AbfHUUEy (ORCPT ); Wed, 21 Aug 2019 16:04:54 -0400 Received: by mail-qk1-f194.google.com with SMTP id d23so3015923qko.3; Wed, 21 Aug 2019 13:04:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=PnHB8gyKyQN8X+3fWDRw3LLnwjDF9vWYPYJU7kI+Ljs=; b=Qb4/QdgAopIiPsSKrI0Ml0FWuBhpglzWZIh34AIf9iP1mPAKLFYigjyoH+2SHsz34F 81taKwT3AOCD3UzL6iPnjsIIABaX//3Lb+s8TX4PxB8BzCZ4o4NkEPmgau+U5WV+UO+D nMfmqHhkFKaY0sYs9lt3ejUsgNLbBu0rXaLEhlUWGP4HwThKtMrCeeFG3JXgIvGyZEEd VXdW/LXakjSdP3TWg+coGg4lY6bBqwtGgDeJI/YihggwX/NMvQFokdp9kiJ0SJFKMOWe 7dOBsGnUKzNodvA9Mwc3NgTOecfTaAo17cBPqd87Vult6Ci2ciYoY+L1alA6zEIUyW+s CQYA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=PnHB8gyKyQN8X+3fWDRw3LLnwjDF9vWYPYJU7kI+Ljs=; b=TYkRRaJNUqU81uGIzh5/vm69uHk31MY/GSqHDEZJ+MLIafaTRx4zk4koBL4BgeO6fZ g7+zpH0OvmF1iu0m6jZV1RtISxtWJcZxdz0tzQOFN2bcdiVMf1/HG0YAksYJkkoL9gzB Wz+oPiBwl4kQSx24xQByBNiYWwqHzzHaY1jjOBmgcK22GN/HbGAwFLCizKPV+jefbJ7q Vg4sRHfbD29Nj2eyKd0Sgib7TtPzj22hu2ap7tGzhnqz7ishaIwG23PKNDEV2ARUtg1p qZbTTNYKiqAVSOf+hrsacyosSjAnSbSYj4l5CB4QALRn89xiUy5+ImsjAnb6UIq/vfZP IXCw== X-Gm-Message-State: APjAAAX+0IEFO8Wd5TXPTS5/+yeJEqk/u5HGfbWLifzn68Y52pHpQI7Y RAPgJ0BgSFX6JkGVQbhIdcw= X-Google-Smtp-Source: APXvYqzd/Qv9AuvHu75iKH8704islEG5IzXmqfXzwc75rcmXXQUqVMYv6u8IerQCnt47p1VJEYr0Ig== X-Received: by 2002:a37:2c41:: with SMTP id s62mr34120263qkh.415.1566417893345; Wed, 21 Aug 2019 13:04:53 -0700 (PDT) Received: from quaco.ghostprotocols.net ([177.195.211.175]) by smtp.gmail.com with ESMTPSA id m194sm10497757qke.123.2019.08.21.13.04.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Aug 2019 13:04:52 -0700 (PDT) From: Arnaldo Carvalho de Melo X-Google-Original-From: Arnaldo Carvalho de Melo Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id 9B23B40340; Wed, 21 Aug 2019 17:04:43 -0300 (-03) Date: Wed, 21 Aug 2019 17:04:43 -0300 To: Yonghong Song Cc: Peter Zijlstra , Daniel Xu , "bpf@vger.kernel.org" , Song Liu , Andrii Nakryiko , "mingo@redhat.com" , 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: <20190821200443.GH3929@kernel.org> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5ecdcd72-255d-26d1-baf3-dc64498753c2@fb.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.12.0 (2019-05-25) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Wed, Aug 21, 2019 at 06:43:49PM +0000, Yonghong Song escreveu: > On 8/21/19 11:31 AM, Peter Zijlstra wrote: > > On Wed, Aug 21, 2019 at 04:54:47PM +0000, Yonghong Song wrote: > >> A lot of bpf-based tracing programs uses maps to communicate and > >> do not allocate ring buffer at all. > > > > 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 :-( Perhaps he's talking about using read(perf_event_fd, ...) after having set it up with perf_event_attr.read_format with the-to-be-implemented PERF_FORMAT_LOST bit? Look at perf_read() and perf_read_one() in kernel/events/core.c. - Arnaldo