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=-0.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 BB47DC67839 for ; Thu, 13 Dec 2018 01:26:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5964820873 for ; Thu, 13 Dec 2018 01:26:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5964820873 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.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 S1726522AbeLMB0n (ORCPT ); Wed, 12 Dec 2018 20:26:43 -0500 Received: from mail.kernel.org ([198.145.29.99]:34770 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726337AbeLMB0n (ORCPT ); Wed, 12 Dec 2018 20:26:43 -0500 Received: from vmware.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 52B5A20851; Thu, 13 Dec 2018 01:26:41 +0000 (UTC) Date: Wed, 12 Dec 2018 20:26:39 -0500 From: Steven Rostedt To: "Dmitry V. Levin" Cc: Peter Zijlstra , Jiri Olsa , Arnaldo Carvalho de Melo , Ingo Molnar , Namhyung Kim , Alexander Shishkin , Thomas Gleixner , "Luis Claudio R. Goncalves" , Eugene Syromyatnikov , Frederic Weisbecker , lkml Subject: Re: [PATCH 1/8] perf: Allow to block process in syscall tracepoints Message-ID: <20181212202639.1978ec88@vmware.local.home> In-Reply-To: <20181213003938.GD24195@altlinux.org> References: <20181206081028.GE4234@hirez.programming.kicks-ass.net> <20181206083400.GA13675@hirez.programming.kicks-ass.net> <20181206131946.2c47f556@vmware.local.home> <20181207085839.GC2237@hirez.programming.kicks-ass.net> <20181207072701.5bc564c7@vmware.local.home> <20181207151105.GB5289@hirez.programming.kicks-ass.net> <20181207151433.20bf0399@vmware.local.home> <20181208104423.GE5289@hirez.programming.kicks-ass.net> <20181208123805.1c158665@vmware.local.home> <20181210101818.GJ5289@hirez.programming.kicks-ass.net> <20181213003938.GD24195@altlinux.org> X-Mailer: Claws Mail 3.15.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 13 Dec 2018 03:39:38 +0300 "Dmitry V. Levin" wrote: > btw, I didn't ask for the implementation to be ugly. > You don't have to introduce polling into the kernel if you don't want to, > userspace is perfectly capable of invoking wait4(2) in a loop. > Just block the tracee, notify the tracer, and let it pick up the pieces. Note, there's been some discussion offlist to only have perf set a flag when it dropped an event and have the ptrace code do the heavy lifting of blocking the task and waking it back up. I think that would be a cleaner solution and wont muck with perf as badly. -- Steve