From owner-svn-src-all@freebsd.org Thu Jan 5 17:13:27 2017 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 0A0B9CA1987; Thu, 5 Jan 2017 17:13:27 +0000 (UTC) (envelope-from markjdb@gmail.com) Received: from mail-pg0-x242.google.com (mail-pg0-x242.google.com [IPv6:2607:f8b0:400e:c05::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id CE844172D; Thu, 5 Jan 2017 17:13:26 +0000 (UTC) (envelope-from markjdb@gmail.com) Received: by mail-pg0-x242.google.com with SMTP id b1so41246963pgc.1; Thu, 05 Jan 2017 09:13:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=YSulPVpv2ZPu7rL/qp6/rMviiOcAmwH2g1ytFvmNA5s=; b=hTMpSlZCVByB6QgMzIssrBDyIjNfgjI4wvmUuxGIsUdnTRFqTfh0uaATgYco8zJnJu IGeI8rEbldVR0sRI51c3gW2+6eJgrWPzSt+PlURziu3XnXqDqN0NZcXlBqHEsl1pZQYj ncIaoT6Sn6j4nwWd3Rxp37VDOPiXqMaPCfKOj00rzyQKae7hF2+hsKg+rHxiXw8AbxFM SvwZO6FHuqfM8f8NwB38W0yrJd8IwWF/6CaUc7usJEx2sEeTZzOGWsbq01XCrzoGEo6M hll0HUM3xEl0wZj/sVM0DYV6+TcFURojErtDuQF5MUHS3yk+w6Onv0TVHZXl/O2vqegW CDgg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=YSulPVpv2ZPu7rL/qp6/rMviiOcAmwH2g1ytFvmNA5s=; b=EOpdzTw7Ukz2EeIbph+AHk00rsdDGKkYMeacRCdmPiJ7KfWo340feB6a+EcwY3E6Xi XlMbbX3qra7KejudePAHrin0dwuoIKXzyTE9fdGejNH3goy43JaJkZ/hE8FIl+6+xd0/ keSnMJm+GwvsexWXimMmFZJQqduND9PrmH00v6wt+p+0B3rKKzBszofebNhN2GvyBzXs MSjRvo87HZNSACaHWL0mxVeEj62IUR3UazoI/ZbKAFBwyh1wBfFmHb0jDkOSCroXMwNB fhRhTCwDSgqOnG7BzSyOdriVcwLUqUbZoj82JbtoHixEvqqETSXowLVGlFGorXlUzgzQ GF3Q== X-Gm-Message-State: AIkVDXKLMLYfSxi7mGjUFByhgVPqyzOiOHrnJ7NURN4/sJzhMVjjUPUjFQB1Gg78VqU+Xw== X-Received: by 10.99.112.66 with SMTP id a2mr134372029pgn.43.1483636406403; Thu, 05 Jan 2017 09:13:26 -0800 (PST) Received: from raichu ([2604:4080:1102:0:ca60:ff:fe9d:3963]) by smtp.gmail.com with ESMTPSA id m19sm47513358pfk.72.2017.01.05.09.13.25 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 05 Jan 2017 09:13:25 -0800 (PST) Sender: Mark Johnston Date: Thu, 5 Jan 2017 09:13:21 -0800 From: Mark Johnston To: Steven Hartland Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r311346 - in head/sys: kern sys vm Message-ID: <20170105171321.GA70590@raichu> References: <201701050144.v051iCso008577@repo.freebsd.org> <3cf413dd-f8d5-4462-9486-0a56adf08b77@freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3cf413dd-f8d5-4462-9486-0a56adf08b77@freebsd.org> User-Agent: Mutt/1.7.2 (2016-11-26) X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 05 Jan 2017 17:13:27 -0000 On Thu, Jan 05, 2017 at 09:16:02AM +0000, Steven Hartland wrote: > Given the use of the number of CPU's for sizing would this play nice > with hot plug CPU's? > > Regards > Steve Not without some work. I don't think it would be a major obstacle to adding hot-plug CPU support on at least 64-bit systems though. > > On 05/01/2017 01:44, Mark Johnston wrote: > > Author: markj > > Date: Thu Jan 5 01:44:12 2017 > > New Revision: 311346 > > URL: https://svnweb.freebsd.org/changeset/base/311346 > > > > Log: > > Add a small allocator for exec_map entries. > > > > Upon each execve, we allocate a KVA range for use in copying data to the > > new image. Pages must be faulted into the range, and when the range is > > freed, the backing pages are freed and their mappings are destroyed. This > > is a lot of needless overhead, and the exec_map management becomes a > > bottleneck when many CPUs are executing execve concurrently. Moreover, the > > number of available ranges is fixed at 16, which is insufficient on large > > systems and potentially excessive on 32-bit systems. > > > > The new allocator reduces overhead by making exec_map allocations > > persistent. When a range is freed, pages backing the range are marked clean > > and made easy to reclaim. With this change, the exec_map is sized based on > > the number of CPUs.