From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Phillips Subject: Re: Distributed storage. Date: Sun, 5 Aug 2007 14:35:04 -0700 Message-ID: <200708051435.04542.phillips@phunq.net> References: <20070731171347.GA14267@2ka.mipt.ru> <200708050106.58383.phillips@phunq.net> <20070805150154.GA32132@2ka.mipt.ru> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org To: Evgeniy Polyakov Return-path: Received: from dsl081-085-152.lax1.dsl.speakeasy.net ([64.81.85.152]:46776 "EHLO moonbase.phunq.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752394AbXHEVfF (ORCPT ); Sun, 5 Aug 2007 17:35:05 -0400 In-Reply-To: <20070805150154.GA32132@2ka.mipt.ru> Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Sunday 05 August 2007 08:01, Evgeniy Polyakov wrote: > On Sun, Aug 05, 2007 at 01:06:58AM -0700, Daniel Phillips wrote: > > > DST original code worked as device mapper plugin too, but its two > > > additional allocations (io and clone) per block request ended up > > > for me as a show stopper. > > > > Ah, sorry, I misread. A show stopper in terms of efficiency, or in > > terms of deadlock? > > At least as in terms of efficiency. Device mapper lives in happy > world where memory does not end and allocations are fast. Are you saying that things are different for a network block device because it needs to do GFP_ATOMIC allocations? If so then that is just a misunderstanding. The global page reserve Peter and I use is available in interrupt context just like GFP_ATOMIC. Regards, Daniel