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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D2E0C433F5 for ; Mon, 18 Apr 2022 09:24:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237426AbiDRJ1B (ORCPT ); Mon, 18 Apr 2022 05:27:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47172 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230488AbiDRJ1B (ORCPT ); Mon, 18 Apr 2022 05:27:01 -0400 Received: from mail-oi1-x22f.google.com (mail-oi1-x22f.google.com [IPv6:2607:f8b0:4864:20::22f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3F05715FD7 for ; Mon, 18 Apr 2022 02:24:22 -0700 (PDT) Received: by mail-oi1-x22f.google.com with SMTP id 12so14204410oix.12 for ; Mon, 18 Apr 2022 02:24:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:from:date:message-id:subject:to; bh=Fl6ppFqSL+ldLOtCtxZXfq1o9zlQYEZKTYtXl+gtm6I=; b=XwFSqeM8sRdiwRjGddB0ngRMEjIBdDhYEEcxd8vn0H8JltIrN/yt91IJpHw7DeUIFH 9KusOs8gDpThLQC3cWrJeMvCDRXVmy9h4UfMHLcibihuNKSETjM4gijKpyxOSgDLh+bo bgTrHj7W4HRlWoC4lkVIJBI05/wbS03JpoLtupt+SqjEZ1kszlKuK+oiAQCBiULnMSA8 oKMhw0fAtSvEgjtiMZOsWIv8o6AE2k3QhcETpf47UKt6YIvi5ISVUDsdgLycz9Rqx2h5 fdCRo3rFUvf9i7OJsKJhvTWtUtq73IfC7uY5hw4hDPkXFJFWjmmPk9kiBDlahNyJfRIq XZqQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=Fl6ppFqSL+ldLOtCtxZXfq1o9zlQYEZKTYtXl+gtm6I=; b=TkchHkqZ5X7QWCA3ZWLpFOOqbnLHUFURqQwqsEGA8UX+DGhD6rMSI1yzRUzCEPSk3b 165LvZIAcGd/O8ciYE+9LDI+Xa74ixrhpOVPks2pozIPWGDtjU84ALXJh8lWjBC/cwjG fpipz0vyhmXIekPgQKfA3DvpKG1ei7uCpJEmLHhkf/DxXpn4pq137+tqdmc3LrFabCnb W7hHuUd3SuYrgaUnlkrlZf/xTgcH7Fanr/uBEQ9oc115Ov7Qicg+2uUg0/noIaOEff6B nPwE51MuHPcMmiWdDUCs+wSZcO0jM+9TvmL0QmtpVABc+tAdoz1NyvaRuJ/m/gEHfkhh DbdA== X-Gm-Message-State: AOAM530PSAvvRrJA5Bwxp3P9aPTyrWWe33mGO145aU/WodIDZ/m/LQzf ppzifueMiUy5NiV+LsbYzhTlfVKhsQUe0cmGqF+ylOzSww== X-Google-Smtp-Source: ABdhPJzO3XAZbCNOVvn4FUJnzKjKOxXLngm71s2oGBeG1HGOGhFKO5mA+A9xH9BD6zVkcgZxvIhuV1nwzU3tlQk+gsE= X-Received: by 2002:a05:6808:1309:b0:2f9:c16f:d58c with SMTP id y9-20020a056808130900b002f9c16fd58cmr6809898oiv.292.1650273861371; Mon, 18 Apr 2022 02:24:21 -0700 (PDT) MIME-Version: 1.0 From: Mahmood Naderan Date: Mon, 18 Apr 2022 11:24:08 +0200 Message-ID: Subject: Effect of sched_latency_ns To: linux-perf-users@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org I would like to test the effect of latency_ns parameter on the execution time of a program. The program is a 16-thread MM implementation and the CPU is Ryzen with 8/16 (cores/threads). I also have created a busy system with stress --cpu 16. The default value of latency_ns is 24,000,000. If I use lower values, the execution time gets longer. If I use larger values, the execution time goes a little bit down. But the problem is when I use perf and see the stats, they vary over multiple executions. This is expected because of real hardware execution, but I am not able to figure out the conclusion about the effect. Example: For 100,000 142,696 context-switches 1,625 cpu-migrations 51,106 page-faults 40.103996890 seconds time elapsed For 24,000,000 62,185 context-switches 379 cpu-migrations 52,929 page-faults 19.424256128 seconds time elapsed For 100,000,000 63,646 context-switches 513 cpu-migrations 52,930 page-faults 19.716886869 seconds time elapsed 54,644 context-switches 487 cpu-migrations 52,894 page-faults 16.788766277 seconds time elapsed Any explanation about the effect? What should I expect? Regards, Mahmood