From owner-freebsd-hackers@freebsd.org Wed Sep 16 11:53:40 2015 Return-Path: Delivered-To: freebsd-hackers@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 A2FA69CD83B; Wed, 16 Sep 2015 11:53:40 +0000 (UTC) (envelope-from mozolevsky@gmail.com) Received: from mail-wi0-x229.google.com (mail-wi0-x229.google.com [IPv6:2a00:1450:400c:c05::229]) (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 2D0FE1347; Wed, 16 Sep 2015 11:53:40 +0000 (UTC) (envelope-from mozolevsky@gmail.com) Received: by wiclk2 with SMTP id lk2so67144756wic.1; Wed, 16 Sep 2015 04:53:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc:content-type; bh=RAhQvhmCVsEIXrRZsE2XUBJE5H1dWnWb7K2X93C+OeA=; b=dnC+PIUXlFQHxYPrnzDEslZyeN4XElUxUqASnA0RRMHfmB8hfB5pmv7gIHOaMc7PyA 2yTORDIf0pEZVzo6W2XcrYDDFZXzum18YkeW8n0sxkLSTLWvhqY0nNQgNy3SkqNPE0cZ nG0UHrUXAidZBHfW6McfXTcytoqpDhSlJO5uvfJxyBrVtRq6xF207S3DZz0gdHwgo7z7 JV2bv0xsq5aKaYlmDyhTMpuiPfiyYGulgZeBGFhHXBiMaOzjEqR6rL6MTMrH4/GZjuV+ 2fT4FccZ0S1QCOmFGj7m5OuGQcPzcTJ5YCyDM8mgBk4mJZCWX9MxlfIxIEpNHJllksly I63A== X-Received: by 10.181.13.166 with SMTP id ez6mr18779967wid.24.1442404417758; Wed, 16 Sep 2015 04:53:37 -0700 (PDT) MIME-Version: 1.0 Sender: mozolevsky@gmail.com Received: by 10.28.55.18 with HTTP; Wed, 16 Sep 2015 04:52:58 -0700 (PDT) In-Reply-To: <3678FC1E-DDC5-4FB2-B6E9-6FC90D0C988E@gid.co.uk> References: <55F88A18.6090504@FreeBSD.org> <20150916035904.GE67105@kib.kiev.ua> <93871ADA-EDA3-481C-9959-1D371AB44479@gid.co.uk> <3678FC1E-DDC5-4FB2-B6E9-6FC90D0C988E@gid.co.uk> From: Igor Mozolevsky Date: Wed, 16 Sep 2015 12:52:58 +0100 X-Google-Sender-Auth: _DFQg-Oibe5b_dGmy7JWDcQFFdI Message-ID: Subject: Re: ECC support To: Bob Bishop Cc: Konstantin Belousov , Hackers freeBSD , Dieter BSD , Andriy Gapon , freebsd-hardware@freebsd.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.20 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 16 Sep 2015 11:53:40 -0000 On 16 September 2015 at 12:34, Bob Bishop wrote: > "The best we can conclude therefore is that any chip size effect is > unlikely to dominate error rates given that the trends are not consistent > across various other confounders such as age and manufacturer.=E2=80=9D > > I=E2=80=99ll admit to talking that point up a bit but it is counterintuit= ive. > Memory designers have always been scared of cosmic rays etc but the > suspected effects simply have not been noticeable. Most likely as they > shrink features ever smaller, other factors like material purity dominate= . > I saw that after I posted, and had a long ponder as to why it would be so. The only thing I could think of is that the fab process was(/is?) large enough to not worry about "nonsense" like cosmic rays &c (but then I've not had much exposure to semi-conductor electronics theory since late 90s). Perhaps we're at a point where the fab process can't really shrink much more with DRAM due to the underlying tech (effectively many tiny RC circuits), which is the reason the manufacturers just stack ranks to get more capacity per DIMM instead of packing more in a single chip?.. --=20 Igor M.