From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-x429.google.com (mail-pf1-x429.google.com [IPv6:2607:f8b0:4864:20::429]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id B844A3BA8E for ; Tue, 27 Nov 2018 13:31:22 -0500 (EST) Received: by mail-pf1-x429.google.com with SMTP id b85so8810385pfc.3 for ; Tue, 27 Nov 2018 10:31:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=YIABtsNAIo9VD6SLByyhPIJX6309Umq5+oQ48uaEGbw=; b=00Aum1lkVce6OXQwsZ4vC/CV7Ngt+4KVuQrYKiH67mYazswhPwyL5hqkOjd41XAQ4a 6NRbap75Ns+YTc0/c0GnGNwNYpjCQweJ6wua6BwHvzrD7okpKHPHm5wcW5jBQ25cex6u Q4dXR0g5fhrUhVAzbZj4+CFtNAdNwh4aLp+oPr788OG+0l8i0QXG9q55rLrrzEPfL1UA HBsWTJ+dPAW6eVLCsS5xFGrYHltQ7gXCJB00IgnKNvALIKnB+eqOHwk4TU0uFAsVJPYU dehoNNUKck/q46L+8iun+GwprKSIVLWQkC/sYHzGyDkdmnUQg1AMTaODt6leiRzBVJMc 9fZg== 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:in-reply-to :references:mime-version:content-transfer-encoding; bh=YIABtsNAIo9VD6SLByyhPIJX6309Umq5+oQ48uaEGbw=; b=HaEAggXw8BsddpiVxYOuqmZ2JgYACpS1T5kd7CgKPwg9AqC1VacdH7rAJXAbsxbc+a Jrg7QndVNotm8Sfpbv7i9KfzRnpVg2sg0phrXASrNeLGaFbnG7puEYEO6lH+R91jyGzD hpFYVrcQCeYYBEO11LjO00AX0P4JhkQWZ+QlkX5WRmeZ9gCmNUT9lmmDsMJrOaf8h573 Odi3+FqOFTxoBjM+jP7rQZ3KcIP65Kf89eTetGaVhvI30bFptQEkYv+XQKlPo++ZwdfS MxbWIUKhO5EiugroULTU6wdBgmJEKmD3CoeVCZasAfysEU7Gx1GfZ7xES4AAcBaCjBys siGg== X-Gm-Message-State: AA+aEWZAKEQIwBoyGF+eUjlAsq3htbEyCiv5cZ0EA8/Hli7rH0vovVeT BAQh6KNolbnik39NbEaFSdCD3A== X-Google-Smtp-Source: AJdET5dmwcWIxBf6ZwgfQR6Ff7zWiJ78rgmYyHXGrC3N5rQ7MGWYd4Qb/dIR9klRP1utDuD1nuV6XA== X-Received: by 2002:a63:4926:: with SMTP id w38mr29034340pga.353.1543343481769; Tue, 27 Nov 2018 10:31:21 -0800 (PST) Received: from xeon-e3 (204-195-22-127.wavecable.com. [204.195.22.127]) by smtp.gmail.com with ESMTPSA id 64sm5646007pff.101.2018.11.27.10.31.21 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 27 Nov 2018 10:31:21 -0800 (PST) Date: Tue, 27 Nov 2018 10:31:14 -0800 From: Stephen Hemminger To: "Holland, Jake" Cc: Dave Taht , Pete Heist , bloat Message-ID: <20181127103114.3f403d8a@xeon-e3> In-Reply-To: <4FB37CD5-0DAB-479E-8C8C-671D442D668E@akamai.com> References: <6C1479A8-43E8-4F89-BCEA-1D28CA3E8589@heistp.net> <87r2fbzrng.fsf@taht.net> <4FB37CD5-0DAB-479E-8C8C-671D442D668E@akamai.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Bloat] one benefit of turning off shaping + fq_codel X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 27 Nov 2018 18:31:22 -0000 On Tue, 27 Nov 2018 18:14:01 +0000 "Holland, Jake" wrote: > On 2018-11-23, 08:33, "Dave Taht" wrote: > Back in the day, I was a huge fan of async logic, which I first > encountered via caltech's cpu and later the amulet. > > https://en.wikipedia.org/wiki/Asynchronous_circuit#Asynchronous_CPU > > ... > > I've never really understood why it didn't take off, I think, in part, > it doesn't scale to wide busses well, and that centrally clocked designs > are how most engineers and fpgas and code got designed since. Anything > with delay built into it seems hard for EEs to grasp.... but I wish I > knew why, or had the time to go play with circuits again at a reasonable > scale. > > At the time, I was told the objections they got were that it uses about 2x the space for the same functionality, and space usage is approximately linear with the chip cost, and when under load you still need reasonable cooling, so it was only considered maybe worthwhile for some narrow use cases. > > I don't really know enough to confirm or deny the claim, and the use cases may have gotten a lot closer to a good match by now, but this was the opinion of at least some of the people involved with the work, IIRC. > > > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat With asynchronous circuits there is too much unpredictablity and instability. Seem to remember there are even cases where two inputs arrive at once and output is non-determistic.