From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH 00/15] bitops: Change bitmap index from int to unsigned long Date: Wed, 25 Feb 2009 16:46:00 +0100 Message-ID: <1235576760.4645.3535.camel@laptop> References: <200902250441.UAA12527@hpdst41.cup.hp.com> <1235544888.4645.2942.camel@laptop> <20090225153757.GP16891@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20090225153757.GP16891@parisc-linux.org> Sender: linux-kernel-owner@vger.kernel.org To: Matthew Wilcox Cc: Justin Chen , linux-arch@vger.kernel.org, bjorn.helgaas@hp.com, justin.chen@hp.com, linux-kernel@vger.kernel.org List-Id: linux-arch.vger.kernel.org On Wed, 2009-02-25 at 08:37 -0700, Matthew Wilcox wrote: > On Wed, Feb 25, 2009 at 07:54:48AM +0100, Peter Zijlstra wrote: > > unsigned int wasn't large enough? > > Adding one more bit only doubles the maximum size. That buys us, what, > another eighteen months until we have to change it again? Unsigned long > seems most sensible to me. Unsigned long long probably isn't worth > doing -- you'd have to be using one eighth of your address space on a > single bitmap. Are you serious? Bitmaps of length 4G-bit (512M-byte) are way past the sanely allocatable size anyway. The complaint was that the signed thingy resulted in out of bounds pointers (apparently unsigned doesn't?) From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from casper.infradead.org ([85.118.1.10]:43169 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754381AbZBYPqW (ORCPT ); Wed, 25 Feb 2009 10:46:22 -0500 Subject: Re: [PATCH 00/15] bitops: Change bitmap index from int to unsigned long From: Peter Zijlstra In-Reply-To: <20090225153757.GP16891@parisc-linux.org> References: <200902250441.UAA12527@hpdst41.cup.hp.com> <1235544888.4645.2942.camel@laptop> <20090225153757.GP16891@parisc-linux.org> Content-Type: text/plain Date: Wed, 25 Feb 2009 16:46:00 +0100 Message-ID: <1235576760.4645.3535.camel@laptop> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Matthew Wilcox Cc: Justin Chen , linux-arch@vger.kernel.org, bjorn.helgaas@hp.com, justin.chen@hp.com, linux-kernel@vger.kernel.org Message-ID: <20090225154600.XgDNYkZx8lKM36s2cZV0aAFJXph8lb7mUy4gal63lSw@z> On Wed, 2009-02-25 at 08:37 -0700, Matthew Wilcox wrote: > On Wed, Feb 25, 2009 at 07:54:48AM +0100, Peter Zijlstra wrote: > > unsigned int wasn't large enough? > > Adding one more bit only doubles the maximum size. That buys us, what, > another eighteen months until we have to change it again? Unsigned long > seems most sensible to me. Unsigned long long probably isn't worth > doing -- you'd have to be using one eighth of your address space on a > single bitmap. Are you serious? Bitmaps of length 4G-bit (512M-byte) are way past the sanely allocatable size anyway. The complaint was that the signed thingy resulted in out of bounds pointers (apparently unsigned doesn't?)