From owner-freebsd-arch Thu Jun 24 3:35:47 1999 Delivered-To: freebsd-arch@freebsd.org Received: from ns1.yes.no (ns1.yes.no [195.204.136.10]) by hub.freebsd.org (Postfix) with ESMTP id 8C8BB15246 for ; Thu, 24 Jun 1999 03:35:38 -0700 (PDT) (envelope-from eivind@bitbox.follo.net) Received: from bitbox.follo.net (bitbox.follo.net [195.204.143.218]) by ns1.yes.no (8.9.1a/8.9.1) with ESMTP id MAA16026 for ; Thu, 24 Jun 1999 12:35:36 +0200 (CEST) Received: (from eivind@localhost) by bitbox.follo.net (8.8.8/8.8.6) id MAA17968 for freebsd-arch@freebsd.org; Thu, 24 Jun 1999 12:35:36 +0200 (MET DST) Received: from localhost.simon-shapiro.org (HELO simon-shapiro.org) (127.0.0.1) by localhost.simon-shapiro.org with SMTP; 23 Jun 1999 23:56:18 -0000 Message-ID: <37717422.251ED67@simon-shapiro.org> Date: Wed, 23 Jun 1999 19:56:18 -0400 From: Simon Shapiro Organization: Simon's Garage X-Mailer: Mozilla 4.6 [en] (X11; I; FreeBSD 3.1-STABLE i386) X-Accept-Language: en MIME-Version: 1.0 To: freebsd-arch@freebsd.org Subject: Intelligent I/O Opportunities Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Hi Y'll When doing block (or raw) I/O to an i2o device, we can easily control the I/O operation in this manner: WRITE: Can be normal write, write-verify, write-through or write back. READ: Can be normal, cached, or prefetched (with pre-fetch amount specified). BOTH: A command can go ``solo'' or be queued. Solo is essentially out-of band, while normal I/O puts the command in the queue, subject to elevator sorts, etc. QUESTION: Is there a way to bring forward such hints into the buf struct? If so, normal drivers can ignore these, but i2o based I/O subsystems can benefit from improved safety, performance, or both. Applying this to the i2o code is trivial, but I need some input. [In case people are not aware of it, Simon is working on an I2O subsystem for FreeBSD. -EE] -- Sincerely Yours, Shimon@Simon-Shapiro.ORG 770.265.7340 Simon Shapiro Unwritten code has no bugs and executes at twice the speed of mouth To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message