Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751254AbVLMLec (ORCPT ); Tue, 13 Dec 2005 06:34:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751189AbVLMLeb (ORCPT ); Tue, 13 Dec 2005 06:34:31 -0500 Received: from mx1.redhat.com ([66.187.233.31]:31452 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1750764AbVLMLeb (ORCPT ); Tue, 13 Dec 2005 06:34:31 -0500 From: David Howells In-Reply-To: <974.1134472981@warthog.cambridge.redhat.com> References: <974.1134472981@warthog.cambridge.redhat.com> <439E1381.2060201@yahoo.com.au> To: David Howells Cc: Nick Piggin , torvalds@osdl.org, akpm@osdl.org, hch@infradead.org, arjan@infradead.org, matthew@wil.cx, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH 1/19] MUTEX: Introduce simple mutex implementation X-Mailer: MH-E 7.84; nmh 1.1; GNU Emacs 22.0.50.1 Date: Tue, 13 Dec 2005 11:34:14 +0000 Message-ID: <1253.1134473654@warthog.cambridge.redhat.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 861 Lines: 32 David Howells wrote: > > Any reason why you're setting up your own style of waitqueue in > > mutex-simple.c instead of just using the kernel's style of waitqueue? > > Because I can steal the code from FRV's semaphores or rw-semaphores, and this > way I can be sure of what I'm doing. And because: struct mutex { int state; wait_queue_head_t wait_queue; }; Wastes 8 more bytes of memory than: struct mutex { int state; spinlock_t wait_lock; struct list_head wait_list; }; on a 64-bit machine if spinlock_t is 4 bytes. Both waste 4 bytes if spinlock_t is 8 bytes. David - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/