From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 4 May 2007 09:23:04 -0700 (PDT) From: Christoph Lameter Subject: Re: [PATCH 08/40] mm: kmem_cache_objsize In-Reply-To: <1178295355.24217.49.camel@twins> Message-ID: References: <20070504102651.923946304@chello.nl> <20070504103157.215424767@chello.nl> <84144f020705040354r5cb74c5fj6cb8698f93ffcb83@mail.gmail.com> <1178295355.24217.49.camel@twins> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: Pekka Enberg , linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, Trond Myklebust , Thomas Graf , David Miller , James Bottomley , Mike Christie , Andrew Morton , Daniel Phillips List-ID: On Fri, 4 May 2007, Peter Zijlstra wrote: > On Fri, 2007-05-04 at 09:09 -0700, Christoph Lameter wrote: > > On Fri, 4 May 2007, Pekka Enberg wrote: > > > > > On 5/4/07, Peter Zijlstra wrote: > > > > Expost buffer_size in order to allow fair estimates on the actual space > > > > used/needed. > > > > We already have ksize? > > ksize gives the internal size, whereas these give the external size. > > I need to know how much space I need to reserve, hence I need the > external size; whereas normally you want to know how much space you have > available, which is what ksize gives. > > Didn't we have this discussion last time? I was cced on that as far as I can tell. The name objsize suggests the size of the object not the slab size. If you want this then maybe call it kmem_cache_slab_size. SLUB distinguishes between obj_size which is the size of the struct that is used and slab_size which is the size of the object after alignment, adding debug information etc etc. See also slabinfo.c for a way to calculate theses sizes from user space. If we really drop SLAB then we wont need this. SLUBs data structures are not opaque. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org