From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: sg regression in 2.6.16-rc5 Date: Fri, 03 Mar 2006 14:42:44 -0500 Message-ID: <44089C34.2030604@garzik.org> References: <4404AA2A.5010703@torque.net> <20060301083824.GA9871@merlin.emma.line.org> <4405E8AA.1090803@rtr.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail.dvmed.net ([216.237.124.58]:63888 "EHLO mail.dvmed.net") by vger.kernel.org with ESMTP id S1751326AbWCCTmy (ORCPT ); Fri, 3 Mar 2006 14:42:54 -0500 In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Linus Torvalds Cc: Steve Byan , Mark Lord , Matthias Andree , Douglas Gilbert , Mark Rustad , linux-scsi@vger.kernel.org, Linux Kernel Mailing List Linus Torvalds wrote: > For example, I think the IDE driver defaults to a maximum transfer of 256 > sectors, and the same number of max scatter-gather entries. Some > controllers will actually lower that, due to silly hw problems. Yep. Just to be specific: 256 max sectors IDE driver, 200 max sectors libata (due to driver not hardware). 256 max s/g entries hardware limit, but due to a IOMMU merging worst case libata (IDE driver too?) winds up with a 128 entry practical limit. Newer SATA controllers eliminate the s/g entry limit and DMA boundary limits, but its still 256 max-sectors for ATAPI (64k for LBA48 ATA). Jeff