From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 16 Aug 1999 19:19:46 +0200 (CEST) From: Andrea Arcangeli Subject: Re: [bigmem-patch] 4GB with Linux on IA32 In-Reply-To: <19990816184848.F14973@mencheca.ch.genedata.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Matthew Wilcox Cc: linux-kernel@vger.rutgers.edu, linux-mm@kvack.org List-ID: On Mon, 16 Aug 1999, Matthew Wilcox wrote: >Have you got some lmbench results to back this up? Does lmbench benchmark the _allocation_ of the memory? If so could you point out to me the exact lmbench command? (you would save me the time for writing such a simple bench ;). I looked a bit at lmbench and it seems to me that all mm tools are measuring the time _after_ the allocation happened (so measuring the hardware bus/cache speed or page-colouring algorithms and not the OS anonymous/shm page-fault time). But maybe I am overlooking something? All bw_mem_rw/bw_mem_cp/bw_mem_rd are _useless_ to benchmark the bigmem patch since as just said once the allocation of memory is completed the performance decrease will be _zero_ and not only close to zero. The only tiny performance hit will happens while allocating a page for clearing it or for doing the COW inside the page-fault handler (if you are going to benchmark it make sure to #undef KMAP_DEBUG). Andrea -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://humbolt.geo.uu.nl/Linux-MM/