From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.8 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 0513E7D089 for ; Thu, 22 Nov 2018 13:59:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389105AbeKWAiG (ORCPT ); Thu, 22 Nov 2018 19:38:06 -0500 Received: from mail-lj1-f195.google.com ([209.85.208.195]:45922 "EHLO mail-lj1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388851AbeKWAiG (ORCPT ); Thu, 22 Nov 2018 19:38:06 -0500 Received: by mail-lj1-f195.google.com with SMTP id s5-v6so8050207ljd.12; Thu, 22 Nov 2018 05:58:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=0FdJWlttdcfx1vvyGNs5jX+WBsrIxwmgJ7nDcXUL+zM=; b=hMV+t8eW1ECVHtpiApxQkz3/dDOsjqt+T3SUJewTdceUmdGcQY9euvpcCKfOm59VkE R0m4eQ41qNd6lEgag829R4WJnKrFA007BeTMCiP8YIux5WQKwcRBtBk9s0aLy5ISngLo bmZt/3MW4aCYzIcwY1PIOAwhNfXCQnEsvl3GR9X/T02GVZ+3KAsUxOGLXHgP3EvauDDG pySwWPJFhg11i3g6NS+xkQs9IlIA4gqtEG/XXB5kOeVPQrK9n3Rf6zZgBaM7w+Td+0br 5J96nsQlek67ksGeCk35D2hwFKLGeDRz/nZSvIP15LURIkBjkH9AjeEbQfqtBMJRRPHt QhGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=0FdJWlttdcfx1vvyGNs5jX+WBsrIxwmgJ7nDcXUL+zM=; b=IRee5cQBilS0DYbOAlX36/57sjp4R286Ajvhvwp9klFsODDjHa7s2X3w1S42Ph0m+K 3hII07wcNJy+BhUayl5oCeEWHJqF3/jfkUDYuzFcrTowvzGQcTDAhHJ4f5IkV7JelZ+E M3/lZbljzk/hmcl1LlSWg+q79FEp3b38SObN8WzkBo3CLO1so7Xsk4ChlOdt9p8S7CPk JwQptQk6aDGjqdbHX93IHciqhVDYQlNcPrLYgN+Mrq/UISTgG6QYM5RsYvWO0Jetr/6F EJ+MczT4bb91NBDOYE/KzMO3bqB9jXzg4qJ3Mw4csmBz5/hfVb0il9Gy4dP0c5BkhiGk j6Ug== X-Gm-Message-State: AA+aEWb97fD9ZKRG7hHZldKNoKso4MxPUejoNm+RPGH+oyCJniJWc4Tz KI17jIkH8J3MLzdSPn3xbS0= X-Google-Smtp-Source: AJdET5c09QDBjdzU99r6gnc2wWMKoS5VXUxBdkPj6g8cx8Bq97CCiEA/6DOH/u4paS9P4O/umiui4Q== X-Received: by 2002:a2e:4299:: with SMTP id h25-v6mr6831255ljf.5.1542895116044; Thu, 22 Nov 2018 05:58:36 -0800 (PST) Received: from uranus.localdomain ([5.18.102.224]) by smtp.gmail.com with ESMTPSA id p23sm7160394lfh.47.2018.11.22.05.58.34 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 22 Nov 2018 05:58:35 -0800 (PST) Received: by uranus.localdomain (Postfix, from userid 1000) id 67ECB4606DE; Thu, 22 Nov 2018 16:58:34 +0300 (MSK) Date: Thu, 22 Nov 2018 16:58:34 +0300 From: Cyrill Gorcunov To: Andy Lutomirski Cc: Daniel Colascione , Andrew Morton , linux-kernel , Linux API , Tim Murray , Primiano Tucci , Joel Fernandes , Jonathan Corbet , Mike Rapoport , Vlastimil Babka , Roman Gushchin , Prashant Dhamdhere , "Dennis Zhou (Facebook)" , "Eric W. Biederman" , rostedt@goodmis.org, tglx@linutronix.de, mingo@kernel.org, linux@dominikbrodowski.net, jpoimboe@redhat.com, Ard Biesheuvel , Michal Hocko , Stephen Rothwell , ktsanaktsidis@zendesk.com, David Howells , "open list:DOCUMENTATION" Subject: Re: [PATCH v2] Add /proc/pid_gen Message-ID: <20181122135834.GA29449@uranus> References: <20181121201452.77173-1-dancol@google.com> <20181121205428.165205-1-dancol@google.com> <20181121141220.0e533c1dcb4792480efbf3ff@linux-foundation.org> <20181121145043.fa029f4f91afddc2a10bb81e@linux-foundation.org> <37255927-1A93-4B8B-A916-B5A3983D56B6@amacapital.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <37255927-1A93-4B8B-A916-B5A3983D56B6@amacapital.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Wed, Nov 21, 2018 at 04:35:34PM -0700, Andy Lutomirski wrote: > > > > I'm going to have Android's systrace and Perfetto use this approach. > > Exactly how many tools signed up to use this feature do you need? > > > >> Those people are the intended audience and the > >> best-positioned reviewers so let's hear from them? > > > > I'm writing plenty of trace analysis tools myself, so I'm part of this > > intended audience. Other tracing tool authors have told me about > > out-of-tree hacks for process atomic snapshots via ftrace events. This > > approach avoids the necessity of these more-invasive hacks. > > Would a tracepoint for pid reuse solve your problem? FWIW we've had similar problem in criu for memory snapshotting, because memory data is PID-driven and snapshots are rather discrete events. So we use task_struct::real_start_time as a second guard agains pid reuse.