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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 38A1BC49ED7 for ; Fri, 20 Sep 2019 08:48:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 042C12086A for ; Fri, 20 Sep 2019 08:48:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568969282; bh=yt5cgxMrcXLx7CYebC21viy43AOHG/F1j8Oa1hUrw2A=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=tD0ipYYlH7UjxHhbKQZBZi0KMxMlgg2bM13JhildxjZND5IFw0xeRG+vxb7dl1hc0 XNkex0MBxZo+iHDskIp0LTa93i7dKGbKRGdH40G8S2bNbdKrL/Ee57ViLS7hmSQvEx cnms0w/HHGYMxyqKBoUBmen45TzrpEbwwUV/5cX8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437840AbfITIsB (ORCPT ); Fri, 20 Sep 2019 04:48:01 -0400 Received: from mail-wm1-f67.google.com ([209.85.128.67]:50219 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404617AbfITIsA (ORCPT ); Fri, 20 Sep 2019 04:48:00 -0400 Received: by mail-wm1-f67.google.com with SMTP id 5so1507412wmg.0 for ; Fri, 20 Sep 2019 01:47:57 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=tBGhwYpczMZ+4bbiY7a42NStzWV0pGWs8gNhSj4LGds=; b=fftI4fnaW2sCTl2nEBtnAA7nZxSqiCU47XXU1YYBVLXSAbXeklUKoJKpxqgYg5gFXi rqxenAtKeI4LAebPOd9en30CYXv71JcbKEWejTw9ByL2E/8wqSKOltxQbhh2k+7EYqlP AqQ+TIWsij4dHV7ACyvuPKdepyNFOewJT93NZrHuUgHUPKUaZx36Wbp1mR0pzns2jyHC nEVwgx4H8j6aW46PtJojvxikeBc2g1hJjpWAELkhhyZu5ULvuwIs4T9JiscjBnPY7xLw PhIO63dscxdQ/pALjc5VeUwbjBqVqS9ndG8jThcaORP2ERidG9urVKiMFlFQ16Tthtsv gYiA== X-Gm-Message-State: APjAAAVDBQK2iAE+1BMtBtvD/Z2YbuGg4xeav0xx5uOEDaHljGXWEpqO +40Qkq5dq4l9CEve56d44Gaeau8z7OTbFkw+2oM= X-Google-Smtp-Source: APXvYqwqdEWgFCjb8JckQEfZzSexOWQLDOIYwWH9sJa7nTiOOVl4cRl8joKa+v2GQgC+t0K/jB/qE5TMJq6/Vnrxdgc= X-Received: by 2002:a7b:c44d:: with SMTP id l13mr2366867wmi.160.1568969276944; Fri, 20 Sep 2019 01:47:56 -0700 (PDT) MIME-Version: 1.0 References: <20190828073130.83800-1-namhyung@kernel.org> <20190828073130.83800-3-namhyung@kernel.org> <20190828144911.GR2263813@devbig004.ftw2.facebook.com> <20190831030321.GA93532@google.com> <20190831045815.GE2263813@devbig004.ftw2.facebook.com> <20190916152325.GD3084169@devbig004.ftw2.facebook.com> In-Reply-To: From: Namhyung Kim Date: Fri, 20 Sep 2019 17:47:45 +0900 Message-ID: Subject: Re: [PATCH 2/9] perf/core: Add PERF_SAMPLE_CGROUP feature To: Song Liu Cc: Tejun Heo , Ingo Molnar , Peter Zijlstra , Arnaldo Carvalho de Melo , LKML , Jiri Olsa , Alexander Shishkin , Stephane Eranian , Li Zefan , Johannes Weiner Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Song, On Thu, Sep 19, 2019 at 3:43 PM Song Liu wrote: > Sharing some offline discussions with Tejun. > > ino in current kernfs is not a good unique ID for cgroup, because it doesn't > increase monotonically. So we need to improve kernfs. > > For 64-bit, we can make the ino monotonic, and use it as the ID. > For 32-bit, we need to make the ino monotonic. and use and > as the 64-bit ID. Thanks for the sharing information! For 32-bit, while the ino itself is not monotonic, gen << 32 + ino is monotonic right? I think we can use the same logic of kernfs id allocation, but not sure what the problem Tejun mentioned before is. Thanks, Namhyung