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=-4.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 86A15C433E1 for ; Thu, 13 Aug 2020 16:02:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5D7EA2078D for ; Thu, 13 Aug 2020 16:02:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Ovv2Va9u" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726486AbgHMQCs (ORCPT ); Thu, 13 Aug 2020 12:02:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56834 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726131AbgHMQCr (ORCPT ); Thu, 13 Aug 2020 12:02:47 -0400 Received: from mail-oi1-x244.google.com (mail-oi1-x244.google.com [IPv6:2607:f8b0:4864:20::244]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A1516C061757 for ; Thu, 13 Aug 2020 09:02:47 -0700 (PDT) Received: by mail-oi1-x244.google.com with SMTP id k4so5500310oik.2 for ; Thu, 13 Aug 2020 09:02:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:reply-to:from:date:message-id :subject:to:cc; bh=OsOO5EM1k8kX5EKcp4tmQWmYqANkLh9Q/4PJEJSeU1o=; b=Ovv2Va9ukCZ2LuqUBDaTJhN+L1JzAE094kjIglcuqaOwLep46eKkgOaPPmswRP3VdF kJnbzrmg9HsLaW5POqozHjGi7C3r51IqhSoG/+jcsrcAr4lwLrIf0EaUava9fki3cGr8 dAYmENwLizujGTLv02SbfOrlfLLF5/32hI6tDdYnVt+5qWC2PWX4u+fU88re5IeyWJhh I+hiZ+dVyjA7Hc4vsI5/9/rkOlUnOcwquj2LSrtLUH5Hif6+rS97zW0HAsH+8r4txN6w jCM4c9aqYGGj175tM0kImKfJx+SuKvWZP5alSwP+lnJOoNUtucUx1RHv5T7b7KnIaTye 55YA== 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:reply-to :from:date:message-id:subject:to:cc; bh=OsOO5EM1k8kX5EKcp4tmQWmYqANkLh9Q/4PJEJSeU1o=; b=DVqk8/K79cjKdlVHsDX9OHnf7ztbLU2ljxmkaTFfqwbKSwQ37Ceipez4Ijb2Mqw+Tw Z/YMF0OEt5iPBVwFV2rxhUZhL5YvyJS5KYHAhaVZJOwnL5AhGwQE/2GSpQQvKyBsns6/ 30sz/8oGHyLzczNd3xx2ItA0TTBPYuOwwa40jN8NNxD2WnbyWS2joWf3Y+PjaajztJ+T /SYSXN+na9YWSwkIOfoC7NmqVjdRuoiKVDTVmDdLXnm+kAuq55dwJ5JRJF/z9RFmHET6 BybYm9yZSDOsHidCRNAgpYyhToHx0hnsScFBjEcUwhClWDDlVrUg5aDBwizxo7EPTQMy 1R8A== X-Gm-Message-State: AOAM532HB7d5q7ENdrdeR4UlZ73gaJddRu31ddChMVW7weJ/ynvnoYgH /PFuRJvbVbDL5IpB5KvtZCgnLo26t54Dr64b7oc= X-Google-Smtp-Source: ABdhPJyI21ylWx7D8cTTmHYPNZwceAnaAJXhT+G3yhXE7WXfzwFLCMKdi5b3maHhtOnG9qdYXcMCsvGITdDSS3dsyyU= X-Received: by 2002:aca:724f:: with SMTP id p76mr3954553oic.35.1597334566887; Thu, 13 Aug 2020 09:02:46 -0700 (PDT) MIME-Version: 1.0 References: <20200809235412.GD25124@SDF.ORG> <20200810034948.GB8262@1wt.eu> <20200811053455.GH25124@SDF.ORG> <20200811054328.GD9456@1wt.eu> <20200811062814.GI25124@SDF.ORG> <20200811074538.GA9523@1wt.eu> <20200812032139.GA10119@1wt.eu> <20200813080646.GB10907@1wt.eu> In-Reply-To: Reply-To: sedat.dilek@gmail.com From: Sedat Dilek Date: Thu, 13 Aug 2020 18:02:34 +0200 Message-ID: Subject: Re: [DRAFT PATCH] random32: make prandom_u32() output unpredictable To: Eric Dumazet Cc: George Spelvin , Amit Klein , "Jason A. Donenfeld" , Andy Lutomirski , Kees Cook , Thomas Gleixner , Peter Zijlstra , Linus Torvalds , netdev , Willy Tarreau Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Aug 13, 2020 at 4:00 PM Eric Dumazet wrote: > > On Thu, Aug 13, 2020 at 1:27 AM Sedat Dilek wrote: > > > > I run a perf session looks like this in my KDE/Plasma desktop-environment: > > > > [ PERF SESSION ] > > > > 1016 2020-08-13 09:57:24 echo 1 > /proc/sys/kernel/sched_schedstats > > 1017 2020-08-13 09:57:24 echo prandom_u32 >> > > /sys/kernel/debug/tracing/set_event > > 1018 2020-08-13 09:57:24 echo traceon > > > /sys/kernel/debug/tracing/events/random/prandom_u32/trigger > > 1019 2020-08-13 09:57:25 echo 1 > /sys/kernel/debug/tracing/events/enable > > > > 1020 2020-08-13 09:57:32 sysctl -n kernel.sched_schedstats > > 1021 2020-08-13 09:57:32 cat /sys/kernel/debug/tracing/events/enable > > 1022 2020-08-13 09:57:32 grep prandom_u32 /sys/kernel/debug/tracing/set_event > > 1023 2020-08-13 09:57:33 cat > > /sys/kernel/debug/tracing/events/random/prandom_u32/trigger > > > > root# /home/dileks/bin/perf record -a -g -e random:prandom_u32 sleep 5 > > > > To be clear : This "perf record -a -g -e random:prandom_u32 sleep 5" > is self sufficient. > > You have nothing to do before (as reported in your email), this is > simply not needed. > > I am not sure why you added all this irrelevant stuff, this is distracting. Initially I followed these Links: Link: https://www.kernel.org/doc/html/v5.8/trace/events.html Link: https://www.kernel.org/doc/html/v5.8/trace/events.html#boot-option Link: http://www.brendangregg.com/perf.html Link: http://www.brendangregg.com/perf.html#DynamicTracing You are right, it's not needed to set and check all these variables as perf says: root# /home/dileks/bin/perf list | grep prandom_u32 random:prandom_u32 [Tracepoint event] So these two steps are indeed enough: root# /home/dileks/bin/perf record -a -g -e random:prandom_u32 sleep 5 root# /home/dileks/bin/perf report --no-children --stdio Lessons learned. - Sedat -