From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [patch][rfc] acpi: do not use kmem caches Date: Mon, 1 Dec 2008 12:18:06 -0500 Message-ID: <20081201171806.GA14074@infradead.org> References: <20081201083128.GB2529@wotan.suse.de> <84144f020812010318v205579ean57edecf7992ec7ef@mail.gmail.com> <20081201120002.GB10790@wotan.suse.de> <4933E2C3.4020400@gmail.com> <20081201133646.GC10790@wotan.suse.de> <4933F14C.7020200@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from bombadil.infradead.org ([18.85.46.34]:54962 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751370AbYLARSK (ORCPT ); Mon, 1 Dec 2008 12:18:10 -0500 Content-Disposition: inline In-Reply-To: <4933F14C.7020200@gmail.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Alexey Starikovskiy Cc: Nick Piggin , Pekka Enberg , Linux Memory Management List , linux-acpi@vger.kernel.org, lenb@kernel.org On Mon, Dec 01, 2008 at 05:14:36PM +0300, Alexey Starikovskiy wrote: > Why then you try to delete ACPICA code, which might be just disabled by > undefining ACPI_USE_LOCAL_CACHE? > If you do want to go that path, you need to create patch against ACPICA, not > Linux code. Sorry dude, but that's not how Linux development works. Please talk to some intel OTC folks to get an advice on how it does. >> Ah OK I misread, that's the cache's freelist... ACPI shouldn't be poking >> this button inside the slab allocator anyway, honestly. What is it >> for? >> > And it is not actually used -- you cannot unload ACPI interpreter, and > this function is called only from there. Care to remove all this dead code? >> Is there a reasonable performance or memory win by using kmem cache? If >> not, then they should not be used > ACPI is still working in machines with several megabytes of RAM and > 100mhz Pentium processors. Do you say we should just not consider them > any longer? > If so, then just delete all ACPICA caches altogether. As Nick is trying to explain you for a while it's not actually going to be a performance benefit for these, quite contrary because of how slab caches waste a lot of memory when only used very lightly or not at all.