From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: Integration of SCST in the mainstream Linux kernel Date: Mon, 04 Feb 2008 11:06:06 -0600 Message-ID: <1202144767.3096.38.camel@localhost.localdomain> References: <1201639331.3069.58.camel@localhost.localdomain> <47A05CBD.5050803@vlnb.net> <47A7049A.9000105@vlnb.net> <1202139015.3096.5.camel@localhost.localdomain> <47A73C86.3060604@vlnb.net> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from accolon.hansenpartnership.com ([76.243.235.52]:40972 "EHLO accolon.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756875AbYBDRGN (ORCPT ); Mon, 4 Feb 2008 12:06:13 -0500 In-Reply-To: <47A73C86.3060604@vlnb.net> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Vladislav Bolkhovitin Cc: Bart Van Assche , Linus Torvalds , Andrew Morton , FUJITA Tomonori , linux-scsi@vger.kernel.org, scst-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org On Mon, 2008-02-04 at 19:25 +0300, Vladislav Bolkhovitin wrote: > James Bottomley wrote: > >>Vladislav Bolkhovitin wrote: > >>So, James, what is your opinion on the above? Or the overall SCSI target > >>project simplicity doesn't matter much for you and you think it's fine > >>to duplicate Linux page cache in the user space to keep the in-kernel > >>part of the project as small as possible? > > > > > > The answers were pretty much contained here > > > > http://marc.info/?l=linux-scsi&m=120164008302435 > > > > and here: > > > > http://marc.info/?l=linux-scsi&m=120171067107293 > > > > Weren't they? > > No, sorry, it doesn't look so for me. They are about performance, but > I'm asking about the overall project's architecture, namely about one > part of it: simplicity. Particularly, what do you think about > duplicating Linux page cache in the user space to have zero-copy cached > I/O? Or can you suggest another architectural solution for that problem > in the STGT's approach? Isn't that an advantage of a user space solution? It simply uses the backing store of whatever device supplies the data. That means it takes advantage of the existing mechanisms for caching. James