From: Herbert Xu Subject: Re: [PATCH] Export symbol ksize() Date: Mon, 16 Feb 2009 09:21:10 +0800 Message-ID: <20090216012110.GA13575@gondor.apana.org.au> References: <20090212104349.GA13859@gondor.apana.org.au> <1234435521.28812.165.camel@penberg-laptop> <20090212105034.GC13859@gondor.apana.org.au> <1234454104.28812.175.camel@penberg-laptop> <20090215133638.5ef517ac.akpm@linux-foundation.org> <1234734194.5669.176.camel@calx> <20090215135555.688ae1a3.akpm@linux-foundation.org> <1234741781.5669.204.camel@calx> <20090215170052.44ee8fd5.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Matt Mackall , Pekka Enberg , "Kirill A. Shutemov" , Christoph Lameter , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-crypto@vger.kernel.org, Geert.Uytterhoeven@sonycom.com To: Andrew Morton Return-path: Received: from rhun.apana.org.au ([64.62.148.172]:49731 "EHLO arnor.apana.org.au" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754560AbZBPBVh (ORCPT ); Sun, 15 Feb 2009 20:21:37 -0500 Content-Disposition: inline In-Reply-To: <20090215170052.44ee8fd5.akpm@linux-foundation.org> Sender: linux-crypto-owner@vger.kernel.org List-ID: On Sun, Feb 15, 2009 at 05:00:52PM -0800, Andrew Morton wrote: > > But kmem_cache_size() would tell you how much extra secret memory there > is available after the object? > > How that gets along with redzoning is a bit of a mystery though. > > The whole concept is quite hacky and nasty, isn't it?. Does > networking/crypto actually show any gain from pulling this stunt? I see no point in calling ksize on memory that's not kmalloced. So no there is nothing to be gained from having kmem_cache_ksize. However, for kmalloced memory we're wasting hundreds of bytes for the standard 1500 byte allocation without ksize which means that we're doing reallocations (and sometimes copying) when it isn't necessary. 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