Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765625AbZFOSap (ORCPT ); Mon, 15 Jun 2009 14:30:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1765328AbZFOSa0 (ORCPT ); Mon, 15 Jun 2009 14:30:26 -0400 Received: from casper.infradead.org ([85.118.1.10]:59682 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1765048AbZFOSaZ (ORCPT ); Mon, 15 Jun 2009 14:30:25 -0400 Subject: Re: [tip:perfcounters/core] x86: Add NMI types for kmap_atomic From: Peter Zijlstra To: Ingo Molnar Cc: Hugh Dickins , linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com, paulus@samba.org, acme@redhat.com, efault@gmx.de, npiggin@suse.de, tglx@linutronix.de, linux-tip-commits@vger.kernel.org, Linus Torvalds , Andrew Morton In-Reply-To: <20090615182549.GD11248@elte.hu> References: <1245077165.6800.497.camel@laptop> <1245080486.6800.561.camel@laptop> <1245089065.13761.19316.camel@twins> <20090615181555.GA11248@elte.hu> <1245089943.13761.19334.camel@twins> <20090615182549.GD11248@elte.hu> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Mon, 15 Jun 2009 20:30:08 +0200 Message-Id: <1245090608.13761.19349.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 970 Lines: 23 On Mon, 2009-06-15 at 20:25 +0200, Ingo Molnar wrote: > * Peter Zijlstra wrote: > but ... look at the APIs i propose above. We dont need _any_ > 'types'. > > That type enumeration is basically an open-coded allocator. If we do > a _real_ allocator (a balanced stack of atomic kmaps) we dont need > any of those indices, and all the potential for mismatch goes away > as well - a stack nests trivially with IRQ and NMI and arbitrary > other contexts. You want types because: - they encode the intent, and can be verified - they help keep track of the max nesting depth In the proposed implementation all type code basically falls away no ! CONFIG_DEBUG_VM, but is kept around for robustness. -- 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/