From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gra-lx1.iram.es (gra-lx1.iram.es [150.214.224.41]) by ozlabs.org (Postfix) with ESMTP id EA09EB7D1E for ; Mon, 1 Feb 2010 20:10:02 +1100 (EST) Date: Mon, 1 Feb 2010 10:09:46 +0100 From: Gabriel Paubert To: Anton Blanchard Subject: Re: [PATCH 5/5] powerpc: Increase NR_IRQS Kconfig maximum to 32768 Message-ID: <20100201090946.GA22966@iram.es> References: <20100131110938.GL2996@kryten> <20100131111012.GM2996@kryten> <20100131111155.GN2996@kryten> <20100131111315.GO2996@kryten> <20100131111403.GP2996@kryten> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20100131111403.GP2996@kryten> Cc: linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sun, Jan 31, 2010 at 10:14:03PM +1100, Anton Blanchard wrote: > > With dynamic irq descriptors the overhead of a large NR_IRQS is much lower > than it used to be. With more MSI-X capable adapters and drivers exploiting > multiple vectors we may as well allow the user to increase it beyond the > current maximum of 512. > > 32768 seems large enough that we'd never have to bump it again (although I bet > my prediction is horribly wrong). It boot tests OK and the vmlinux footprint > increase is only around 500kB due to: Only 1/2 MB? I'm running Linux on 12 year old PPC machines which have 16MB or RAM (ok, they are still running an old kernel, but a few patches like this and they wont't even boot). The kernels I have are well below 1MB, code+data+bss. Yes it is configurable, thanks, and 64 is enough for these machines (8259 plus an MPIC), so it's not that crucial. What I object to is calling 1/2MB negligible. Gabriel