From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 14 Jan 2005 13:02:28 +0100 (CET) From: Roman Zippel Subject: Re: page table lock patch V15 [0/7]: overview In-Reply-To: <20050114041421.GA41559@muc.de> Message-ID: References: <41E4BCBE.2010001@yahoo.com.au> <20050112014235.7095dcf4.akpm@osdl.org> <20050112104326.69b99298.akpm@osdl.org> <41E73EE4.50200@linux-m68k.org> <20050114041421.GA41559@muc.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Andi Kleen Cc: Christoph Lameter , Andrew Morton , nickpiggin@yahoo.com.au, torvalds@osdl.org, hugh@veritas.com, linux-mm@kvack.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, benh@kernel.crashing.org List-ID: Hi, On Fri, 14 Jan 2005, Andi Kleen wrote: > > But there might be a loss in the UP case. Spinlocks are optimized away, > > but your cmpxchg emulation enables/disables interrupts with every access. > > Only for 386s and STI/CLI is quite cheap there. But it's still not free and what about other archs? Why not just check __HAVE_ARCH_CMPXCHG and provide a replacement, which is guaranteed cheaper if no interrupt synchronisation is needed. bye, Roman -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org