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=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 D4DD4C10DCE for ; Thu, 12 Mar 2020 17:09:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F4E2206FA for ; Thu, 12 Mar 2020 17:09:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="dpPEQIvp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726442AbgCLRJs (ORCPT ); Thu, 12 Mar 2020 13:09:48 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:44343 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726085AbgCLRJs (ORCPT ); Thu, 12 Mar 2020 13:09:48 -0400 Received: by mail-wr1-f68.google.com with SMTP id l18so8435307wru.11 for ; Thu, 12 Mar 2020 10:09:45 -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:user-agent; bh=QEESwEEJWVk/Eaie2wY+AKo8HU4RSekgrz+DHvxmm5E=; b=dpPEQIvpVfuOgU6AmC+A57NwArmXTZaDNTHjN8QoeqJuHN8YX4WC4af9BgX2fC2YHo waxiAFjkmisGXMJrpZ2Lp0WwhGWQluI9ZqrVlsoimGCJ0cOkjl/7V69uZU/IjmS3z4zP F0okTfOQ0LxnKIaVSKhA5WEHd1va+aUSR0a5sfPQ7MBEUbTJgmzkRwV7TJrXZ9DyT7uZ 6Yh+RvsFaX41Nl0Ze/H6x3mQWBquZcDQWCBe5LLw5P3ScIaT8lvLMlV0BQc2oTV8nZOR 1k1rPUtZwHnZPlmV9fS38zIDKg87G+5Q6pK8b/KtTqLgIR/ucwK0e5Ozene0MDaHRo2G r/pg== 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=QEESwEEJWVk/Eaie2wY+AKo8HU4RSekgrz+DHvxmm5E=; b=MsUkDLL01EU+6C4ZO5pEFgqJn9PEBqA+YP6LwHYThQAlnK2gvmKRt1X0AL2HCMEZsb 1rQhsWdmzQ0toL1i+RMz9dSLVFggZCzFSoKu5gpbh/qmFPy6y+FkWYyAp5HhtdTCe3qa YhAG3YO/RcUNyyuVApwhtcMNV8Gsdr4MZk5ADuUFjjCWIRojRCtuYY0Y6x1KbGuoeG+Z c3FPsp4ll2lp2qKt3vbsu0v1EplZU1rg32UXBmTS7njMZUkrF2ZZHta0ITY5rXUTOVck S6N4d0+WihDlnmS1VWLtqCmf7pbhLqfBEH+AzeNxM70dzTjQ8Cc0zZI3yUaYsg5cCBq3 JTdw== X-Gm-Message-State: ANhLgQ2myMHHkitnLEOoRis4MCfZy8ufDmM2E4TbBhxgMeybpeIVfwIN fPwM36Es6VHafCeB84TlEA== X-Google-Smtp-Source: ADFU+vsscIblCfkyjI7U5u1LcYlZrU/edQsOnnaoqZAKPyti+cuA4nnArYjtbW9q9ubdiiVC7GJ/pg== X-Received: by 2002:adf:ec45:: with SMTP id w5mr11889324wrn.230.1584032984978; Thu, 12 Mar 2020 10:09:44 -0700 (PDT) Received: from avx2 ([46.53.253.3]) by smtp.gmail.com with ESMTPSA id d1sm13661714wrw.52.2020.03.12.10.09.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Mar 2020 10:09:44 -0700 (PDT) Date: Thu, 12 Mar 2020 20:09:42 +0300 From: Alexey Dobriyan To: Peter Zijlstra Cc: mingo@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] sched: make nr_running() return "unsigned int" Message-ID: <20200312170942.GA7151@avx2> References: <20200311210608.GA4517@avx2> <20200312104427.GR12561@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200312104427.GR12561@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 12, 2020 at 11:44:27AM +0100, Peter Zijlstra wrote: > On Thu, Mar 12, 2020 at 12:06:08AM +0300, Alexey Dobriyan wrote: > > I don't anyone have been crazy enough to spawn 2^32 threads. > > It'd require absurd amounts of physical memory. > > And we're going to 5 level page-tables because 48 bits physical isn't > enough. 57 bits of physical is plenty space to spawn that many tasks and > still have some left over. > > Now 32 bit tasks is indeed insane, but memory isn't the problem. The > actual limit is the pid-space, which is 30 bits. Indeed, pid space limit is even better!