From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ido Yariv Subject: Re: [RFC 1/2] mmc: davinci: Eliminate spurious interrupts Date: Sun, 29 Jan 2012 21:37:10 +0200 Message-ID: <20120129193710.GA24514@WorkStation> References: <4F1E9194.90608@mvista.com> <1327403766-962-1-git-send-email-ido@wizery.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-ww0-f44.google.com ([74.125.82.44]:39740 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753578Ab2A2ThU (ORCPT ); Sun, 29 Jan 2012 14:37:20 -0500 Received: by wgbed3 with SMTP id ed3so3807194wgb.1 for ; Sun, 29 Jan 2012 11:37:18 -0800 (PST) Content-Disposition: inline In-Reply-To: Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: "Rajashekhara, Sudhakar" Cc: "davinci-linux-open-source@linux.davincidsp.com" , "linux-mmc@vger.kernel.org" , Chris Ball , "Nori, Sekhar" Hello Sudhakar, On Fri, Jan 27, 2012 at 08:11:55AM +0000, Rajashekhara, Sudhakar wrote: > I tested both these patches and they work fine on the OMAP-L138 EVM. I > observed that with these patches the number of interrupts during a transfer > are less compared to earlier. For a 100 MB transfer, I could see around > 700-800 interrupts less. Did you see any performance improvement with these > patches? Thanks for testing these. The difference in the number of interrupts, or rather the ratio, depends on the scenario you're working on. The spurious patch has an effect on non-dma transfers, while the polling optimization affects small (i.e. up to 128 bytes) transactions. I expect these to have a greater impact on SDIO scenarios than on SD scenarios. Regarding the performance improvement, these patches were tested using a WLAN SDIO adapter, which requires quite a few small transactions. The polling optimization had an impact of around 10-15% in throughput. The spurious patch did not have any noticeable effect on throughput, but did lower the number of interrupts by up to 25% in some cases. Thanks, Ido.