From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757449Ab0IGO7p (ORCPT ); Tue, 7 Sep 2010 10:59:45 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:40832 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756518Ab0IGO7k (ORCPT ); Tue, 7 Sep 2010 10:59:40 -0400 Date: Tue, 7 Sep 2010 10:59:36 -0400 From: Christoph Hellwig To: Nikos Mavrogiannopoulos Cc: Christoph Hellwig , Herbert Xu , Linux Crypto Mailing List , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: RFC: Crypto API User-interface Message-ID: <20100907145936.GA23178@infradead.org> References: <20100907084213.GA4610@gondor.apana.org.au> <20100907140646.GA31921@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-08-17) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 07, 2010 at 04:57:04PM +0200, Nikos Mavrogiannopoulos wrote: > Or that someone is not really aware of some cryptographic uses. > Embedded systems have crypto accelerators in hardware available > through kernel device drivers. In the systems I worked the > accelerators via a crypto device interface gave a 50x to 100x boost in > crypto operations and relieved the CPU from doing them. An interface to external crypto co-process _can_ be useful. It certainly isn't for the tiny requests where mr crackhead complains about the overhead. So if we do want to design an interface for addons cards we need to expose a threshold from which it makes sense to use it, and not even bother using for the simply software in-kernel algorithms. Which is something that could be done easily using a variant of Herbert's interface.