From: Herbert Xu Subject: Re: [PATCH 0/2] crypto: omap-sha1-md5: OMAP3 SHA1 & MD5 driver Date: Wed, 14 Apr 2010 14:44:23 +0800 Message-ID: <20100414064423.GA20555@gondor.apana.org.au> References: <4BC43BEB.90901@nokia.com> <20100413100308.GA9600@gondor.apana.org.au> <4BC443DB.1030602@nokia.com> <20100413120243.GA10822@gondor.apana.org.au> <4BC46ADB.3000501@nokia.com> <20100413144527.GC12695@gondor.apana.org.au> <4BC48AE1.4010103@jdland.co.il> <4BC48C08.7040608@nokia.com> <20100414004453.GA18044@gondor.apana.org.au> <4BC562BB.4040800@nokia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: ext Uri Simchoni , "linux-crypto@vger.kernel.org" To: Dmitry Kasatkin Return-path: Received: from ringil.hengli.com.au ([216.59.3.182]:45403 "EHLO arnor.apana.org.au" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753365Ab0DNGod (ORCPT ); Wed, 14 Apr 2010 02:44:33 -0400 Content-Disposition: inline In-Reply-To: <4BC562BB.4040800@nokia.com> Sender: linux-crypto-owner@vger.kernel.org List-ID: On Wed, Apr 14, 2010 at 09:37:47AM +0300, Dmitry Kasatkin wrote: > > Like just with import/export. > Problems for hw: > > 1. To have a good performance with DMA we need to have large buffer. > Not just 64 bytes block. state becomes large Sure. But it shouldn't be up to the driver to merge operations. Higher layers (either the end-user or the crypto API) should perform merging. We don't put request merging into storage drivers for a reason. > 2. supporting concurrent requests means switching HW state and it takes > a time. Well that's just the way it is. I'm not saying that it's going to occur frequently, but if it does, you need to support it. > All that burden significantly slowdown hw acceleration and increase CPU > load. > > I guess my points are understandable. I understand your concerns, but these are really limitations common to all off-chip acceleration. If you have to write drivers for them, then you'll have to deal with these issues. Cheers, -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt