From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.5 required=5.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,HTML_MESSAGE,MAILING_LIST_MULTI, RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.2 Received: from minnie.tuhs.org (minnie.tuhs.org [45.79.103.53]) by inbox.vuxu.org (OpenSMTPD) with ESMTP id 8c4fd616 for ; Fri, 17 Jan 2020 16:02:20 +0000 (UTC) Received: by minnie.tuhs.org (Postfix, from userid 112) id 51DC89C108; Sat, 18 Jan 2020 02:02:19 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id DF1429C0F7; Sat, 18 Jan 2020 02:01:08 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=bsdimp-com.20150623.gappssmtp.com header.i=@bsdimp-com.20150623.gappssmtp.com header.b="munkgvBs"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id 1FF579C0F7; Sat, 18 Jan 2020 02:01:06 +1000 (AEST) Received: from mail-qk1-f181.google.com (mail-qk1-f181.google.com [209.85.222.181]) by minnie.tuhs.org (Postfix) with ESMTPS id BED379B842 for ; Sat, 18 Jan 2020 02:01:01 +1000 (AEST) Received: by mail-qk1-f181.google.com with SMTP id r14so23087370qke.13 for ; Fri, 17 Jan 2020 08:01:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=EciiI8y9u3kuA+tTemUw3ZIxbwfKrzwpmBhVUmhUNrA=; b=munkgvBsr13VWmasZk2QEO2rwRDBmBDazLUR4dfPutE9QOm4+tXh6F7QQoznf5WArF LYUIKFibWkYvj6+R41kb5/LT1obZDtn+2fPj9C2AUFoixispqCMSeH2aFI//gN/zj/Ie /g0GATGLCnlYp0eZqjC0BL+9Kv/s0JTJ0sByn40JYyY/c4OB4pBpiK66HMSLGYI74TOe CjjTkCQzIYt3Sw2+WTDnrQIrmg/0Bl5Ev+LRg5Xdp3HXMXgfK6/iaSJFY1lMiW63EjjT 4QazRsEQEJCNum+IYu4IGQrIEngaJOlICk8KwY4nA3uRKwPXurnZ5opGPHVA0If8u8lg b2Jg== 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:from:date :message-id:subject:to:cc; bh=EciiI8y9u3kuA+tTemUw3ZIxbwfKrzwpmBhVUmhUNrA=; b=guJk77FM0uTJ6fmBoo+TeRGIaJhbzibaQ7+kyFDH3aF6e7LW/6hL2eizGEHeMdyWGM tQeLwDsG2OaAxa3zuEFgx/snpgE10KTCg64YsvNAthoODYkOFHig4a8GT0Gz8MDSb6tn HDl+wTquXtYvzEPOULxplimQfQcqZZYs2LDtN8u4g+ckbo/gFTnUPuJziGKXDBJymyvG hgBqaOH+yeJpUMIDjhUGLj7XMU++ENyjbM294DgoVNj2vvJAd8WkUuv/iQoDotVShbS6 SqthTbAMrygGyzh3y/etaytXWeMASCgQo9AfjhDd/2RWCclzC5zjhv/46gpUuJc5qYLG pqSg== X-Gm-Message-State: APjAAAWH+ixj0srTG+AnneCf8kjUvU/SW82sf5LKpyMs1CjB+uv1J8Jw yWmPXpSIRgAW0kOSRlDhiM8MMkm5wrn6T/vjNVaAuYyE X-Google-Smtp-Source: APXvYqxYZMboFNW3s5AQ26VBBq+kTNKzOoESn07v04w2xMeuy0cH7inmc43U25uTHVlGrA9cCn9+tstWtaEeC8WsvFQ= X-Received: by 2002:a37:a80a:: with SMTP id r10mr36319151qke.240.1579276860660; Fri, 17 Jan 2020 08:01:00 -0800 (PST) MIME-Version: 1.0 References: <202001171431.00HEV3gF020029@tahoe.cs.Dartmouth.EDU> <20200117152334.GJ28686@mcvoy.com> In-Reply-To: <20200117152334.GJ28686@mcvoy.com> From: Warner Losh Date: Fri, 17 Jan 2020 09:00:48 -0700 Message-ID: To: Larry McVoy Content-Type: multipart/alternative; boundary="000000000000483aea059c580c72" Subject: Re: [TUHS] Lions book X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: The Eunuchs Hysterical Society , Doug McIlroy Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" --000000000000483aea059c580c72 Content-Type: text/plain; charset="UTF-8" On Fri, Jan 17, 2020 at 8:24 AM Larry McVoy wrote: > On Fri, Jan 17, 2020 at 09:50:24AM -0500, Clem Cole wrote: > > 6th Edition is clear and if you want to understand what it takes and how > it > > works, John's commentary it difficult to beat. > > It's a good starting point but it's pretty outdated. I like to go on and > on about how much I love the SunOS 4.x kernel but it is outdated as well. > > I wish there was a v6/SunOS like kernel that was as clean but had good > support for SMP and NUMA and TCP offload (and probably a long list of > other useful stuff I've forgotten). > > Teaching kids how a single threaded kernel works is cool but it's > also misleading, the world has gotten a lot more complex. And while > the kernels of decades ago were clean and simple, I don't know of > a kernel to point people to that has the clean code that SunOS had. > Solaris isn't it, though it has some bright spots. Linux is meh, it's > better than nothing by a lot but I would not point to it as "read this, > kid, you'll see the architecture". It's not clear there is a good > answer. > It's but the first step on the road to understanding. I'd been working on the FreeBSD kernel for years when I re-read the Lions book. The stark simplicity of the v6 kernel helped everything suddenly 'click' into place in the code I was reading in the FreeBSD kernel, even with 30ish years of changes to the v6 code base that lead to the FreeBSD kernel... Newer systems are a lot more complicated. And they need to be to get the full performance out of the system. Yet understanding the basics without the extra clutter has great value. Warner --000000000000483aea059c580c72 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


=
On Fri, Jan 17, 2020 at 8:24 AM Larry= McVoy <lm@mcvoy.com> wrote:
<= /div>
On Fri, Jan 17, 2020= at 09:50:24AM -0500, Clem Cole wrote:
> 6th Edition is clear and if you want to understand what it takes and h= ow it
> works, John's commentary it difficult to beat.

It's a good starting point but it's pretty outdated.=C2=A0 I like t= o go on and
on about how much I love the SunOS 4.x kernel but it is outdated as well.
I wish there was a v6/SunOS like kernel that was as clean but had good
support for SMP and NUMA and TCP offload (and probably a long list of
other useful stuff I've forgotten).

Teaching kids how a single threaded kernel works is cool but it's
also misleading, the world has gotten a lot more complex.=C2=A0 And while the kernels of decades ago were clean and simple, I don't know of
a kernel to point people to that has the clean code that SunOS had.
Solaris isn't it, though it has some bright spots.=C2=A0 Linux is meh, = it's
better than nothing by a lot but I would not point to it as "read this= ,
kid, you'll see the architecture".=C2=A0 It's not clear there = is a good
answer.

It's but the first step on = the road to understanding. I'd been working on the FreeBSD kernel for y= ears when I re-read the Lions book. The stark simplicity of the v6 kernel h= elped everything suddenly 'click' into place in the code I was read= ing in the FreeBSD kernel, even with 30ish years of changes to the v6 code = base that lead to the FreeBSD kernel...

Newer syst= ems are a lot more complicated. And they need to be to get the full perform= ance out of the system. Yet understanding the basics without the extra clut= ter has great value.

Warner=C2=A0
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