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=-3.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, FSL_HELO_FAKE,HEADER_FROM_DIFFERENT_DOMAINS,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 A3828C433DF for ; Thu, 20 Aug 2020 17:42:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7F035208B3 for ; Thu, 20 Aug 2020 17:42:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Z+WGG4b4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728454AbgHTRmA (ORCPT ); Thu, 20 Aug 2020 13:42:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48420 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727895AbgHTRlo (ORCPT ); Thu, 20 Aug 2020 13:41:44 -0400 Received: from mail-pf1-x442.google.com (mail-pf1-x442.google.com [IPv6:2607:f8b0:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 831C4C061385; Thu, 20 Aug 2020 10:41:42 -0700 (PDT) Received: by mail-pf1-x442.google.com with SMTP id a79so1381762pfa.8; Thu, 20 Aug 2020 10:41:42 -0700 (PDT) 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; bh=oDyvq15BnfthkLtUukIEJz89Sj2Uqn2+fWCc9qUql5I=; b=Z+WGG4b4dkuKHsVtQe1i9WduYBqyH8S4uKxDElpd5cXsi4H11GIlZWCcZgd657XegK uXT4JpFirhXkXu2XTJxbGr5kFdHmoP1OHsrCr6Qthuzimm9pMZzi5zXTgR6Sv5BgXyDs hAhjr2OCzC2ulfDbsdYYA0LsBy0GFR/kM86YP/n5Exz7CmfTxKOvL7qShI/d6Ll+fa8n Bi/NHJ8ocQ4qJoBa0SbGaagVawc0sq0uBEW8OKbSQRZBvqrd/tBRPv8bIRqvQdvoLMZ/ mSZXUw6GLC8ziVIN0UOUCm0rcnPhT9ElfrcwW67Ze23Tq2PGkJi5fpezXOZP/Ac4DgTY Hliw== 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; bh=oDyvq15BnfthkLtUukIEJz89Sj2Uqn2+fWCc9qUql5I=; b=frW0kT98idrzSCKRULlgMqg+MqEfS9aoBzoJm1oOg3FOwPII3sz6wa3fpilCtAuLqB qxU050XFz/2lZK7uqQb3oFYPPt+UTSsPTikmpzHRMQlAdtPNY+lFn/pQP7ovDKkFHD4w Up1gsrW28cYI29rxNwPDW0mv4lDAZBYhpIOG1vyZk7dMt4lSPamDd8/3ND2H9gZg1EQL PKDH7wJ48cI720SoTNan5wyebpbIbNQgqe7CRB9BTbiulb4QTvuRE+afPFvlTIXPxWkE MPS2ZLVQbx+kXA/yjNZw7iEmWoqVdlWjjlCt/1+omX3VlR5HGmGmdjr60P56Zwo/URyo QjCA== X-Gm-Message-State: AOAM530mVA5GLWxNoIpmrU752bgKffDOfWSyfjiykmqbyt1rgI2jmLwu l5LzXSYe/HNZ2tF/s6+8JZY= X-Google-Smtp-Source: ABdhPJwLc9pERZHVMQlxakOJ6eWDFDhXz9bYZmx7M4I1O/HKPbfxjfH2YWKYleJW+BZ4TawkiN2DPg== X-Received: by 2002:a62:fc8c:: with SMTP id e134mr3018219pfh.113.1597945301788; Thu, 20 Aug 2020 10:41:41 -0700 (PDT) Received: from gmail.com ([2601:600:9b7f:872e:a655:30fb:7373:c762]) by smtp.gmail.com with ESMTPSA id y10sm2698316pjv.55.2020.08.20.10.41.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Aug 2020 10:41:41 -0700 (PDT) Date: Thu, 20 Aug 2020 10:41:39 -0700 From: Andrei Vagin To: Eugene Lubarsky Cc: linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, adobriyan@gmail.com, dsahern@gmail.com, Andy Lutomirski , Arnd Bergmann , Oleg Nesterov Subject: Re: [RFC PATCH 0/5] Introduce /proc/all/ to gather stats from all processes Message-ID: <20200820174139.GA919358@gmail.com> References: <20200810145852.9330-1-elubarsky.linux@gmail.com> <20200812075135.GA191218@gmail.com> <20200814010100.3e9b6423@eug-lubuntu> MIME-Version: 1.0 Content-Type: text/plain; charset=koi8-r Content-Disposition: inline In-Reply-To: <20200814010100.3e9b6423@eug-lubuntu> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Aug 14, 2020 at 01:01:00AM +1000, Eugene Lubarsky wrote: > On Wed, 12 Aug 2020 00:51:35 -0700 > Andrei Vagin wrote: > > > Maybe we need resurrect the task_diag series instead of inventing > > another less-effective interface... > > I would certainly welcome the resurrection of task_diag - it is clearly > more efficient than this /proc/all/ idea. It would be good to find out > if there's anything in particular that's currently blocking it. Unfotunatly, I don't have enough time to lead a process of pushing task_diag into the upstream. So if it is interesting for you, you can restart this process and I am ready to help as much as time will permit. I think the main blocking issue was a lack of interest from the wide audience to this. The slow proc is the problem just for a few users, but task_diag is a big subsystem that repeats functionality of another subsystem with all derived problems like code duplication. Another blocking issue is a new interface. There was no consensus on this. Initially, I suggested to use netlink sockets, but developers from non-network subsystem objected on this, so the transaction file interface was introduced. The main idea similar to netlink sockets is that we write a request and read a response. There were some security concerns but I think I fixed them. > > This RFC is mainly meant to check whether such an addition would > be acceptable from an API point of view. It currently has an obvious > performance issue in that seq_file seems to only return one page at a > time so lots of read syscalls are still required. However I may not > have the time to figure out a proposed fix for this by myself. > Regardless, text-based formats can't match the efficiency of task_diag, > but binary ones are also possible. I don't have objections to this series. It can be an option if we will decide that we don't want to do a major rework here. Thanks, Andrei