From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Mason Subject: Re: [RFC][WIP] DIO simplification and AIO-DIO stability Date: Thu, 23 Feb 2006 20:01:32 -0500 Message-ID: <200602232001.34327.mason@suse.com> References: <20060223072955.GA14244@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: akpm@osdl.org, sct@redhat.com, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, kenneth.w.chen@intel.com, pbadari@us.ibm.com, linux-kernel@vger.kernel.org, sonny@burdell.org Return-path: Received: from mail.suse.de ([195.135.220.2]:47292 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S932275AbWBXBBs (ORCPT ); Thu, 23 Feb 2006 20:01:48 -0500 To: suparna@in.ibm.com In-Reply-To: <20060223072955.GA14244@in.ibm.com> Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Thursday 23 February 2006 02:29, Suparna Bhattacharya wrote: > DIO code complexity and stability concerns were discussed way back during > OLS and Kernel summit last year. Still, the lack of a solid alternative and > motivation to subject oneself to the test of courage and delicate balance > that fiddling with this code entails, has meant that gingerly applying > fixes and bandaids as and when bugs are found, and moving on thereafter, > continues to be the most palatable option. > > A recent AIO-DIO bug reported by Kenneth Chen, came very close > to being the proverbial last straw for me. Hence, here is a rough attempt > to put together a (currently WIP) draft towards DIO code simplication, > based on suggestions that some of you have brought up at various times. > Several details, e.g. range locking implementation still need to be fleshed > out completely, ideas/comments/suggestions would be welcome. I'm really in favor of this, and had actually started an implementation a while back. At the time, I posted a different version that added yet another semaphore but simplified the rest of the locking (and held no locks during the dio/aio). I'll try to dig up my original radix tagging code. I'm not sure if I kept it, but it did pass Daniel's dio vs buffer io racing tests at the time. -chris