From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: [PATCH 5/6] ARM: OMAP2: drop redundant pending write check for gptimer Date: Sun, 7 Dec 2008 17:06:24 +0000 Message-ID: <20081207170624.GA17640@flint.arm.linux.org.uk> References: <20081205023737.3868.78857.stgit@localhost> <20081205024121.3868.18876.stgit@localhost> <20081207112511.GB1646@flint.arm.linux.org.uk> <13B9B4C6EF24D648824FF11BE8967162036D05AD4C@dlee02.ent.ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from caramon.arm.linux.org.uk ([78.32.30.218]:37400 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754104AbYLGRGq (ORCPT ); Sun, 7 Dec 2008 12:06:46 -0500 Content-Disposition: inline In-Reply-To: <13B9B4C6EF24D648824FF11BE8967162036D05AD4C@dlee02.ent.ti.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "Woodruff, Richard" Cc: Tony Lindgren , "linux-arm-kernel@lists.arm.linux.org.uk" , Kevin Hilman , Paul Walmsley , "linux-omap@vger.kernel.org" On Sun, Dec 07, 2008 at 08:55:54AM -0600, Woodruff, Richard wrote: > Yes, NOHZ is _poor_ today in respect to needless reprogramming. Code can > be improved. I have sent Thomas a patch for the same which is in the MM > tree for a while now. When I discussed this problem with Thomas, his reaction was rather negative due to there being conflicting requirements between this and ia64. And quite frankly I think that the OMAP behaviour is utter madness - taking as long as it does to update the timer registers means that no matter what you do, you _will_ be paying a penalty for that hardware. Let's hope that later OMAP designs sanitise the timer hardware so it doesn't take stupid amounts of time to write to the registers, posted mode or not.