From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: Change in mmap driver performance from 2..6.38 to 2.6.39 Date: Mon, 11 Jul 2011 07:42:03 -0700 Message-ID: <20110711144202.GE5783@atomide.com> References: <4E1B06FD.5090107@balister.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mho-03-ewr.mailhop.org ([204.13.248.66]:28002 "EHLO mho-01-ewr.mailhop.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754002Ab1GKOmH (ORCPT ); Mon, 11 Jul 2011 10:42:07 -0400 Content-Disposition: inline In-Reply-To: <4E1B06FD.5090107@balister.org> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Philip Balister Cc: "linux-omap@vger.kernel.org" * Philip Balister [110711 07:23]: > I have a device drier that uses a mmap'd section of memory to expose > dma buffers to user space. (https://github.com/balister/linux-omap-philip/blob/e100-2.6.38/drivers/misc/usrp_e.c). > > I have it running on the 2.6.38 and 2.6.39 kernel, but it looks like > read performance is much slower in the .39 version than the .28 > version. > > Does anyone know what changed between these two kernel versions and > how it might fix it? Maybe try git bisect it to some commit? You can use quilt to keep applying the temporary patches needed in between test builds for your driver.. Or maybe git allows that somehow too. Tony