From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King Subject: Re: USB interrupt times Date: Wed, 15 Aug 2012 10:15:54 +0100 Message-ID: <20120815091554.GD7105@flint.arm.linux.org.uk> References: <20120814103936.GA7105@flint.arm.linux.org.uk> <20120814121804.GC7105@flint.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from caramon.arm.linux.org.uk ([78.32.30.218]:38986 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751463Ab2HOJQE (ORCPT ); Wed, 15 Aug 2012 05:16:04 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Jiri Kosina Cc: linux-input@vger.kernel.org, linux-usb@vger.kernel.org, Greg Kroah-Hartman , Henrik Rydberg On Wed, Aug 15, 2012 at 11:02:37AM +0200, Jiri Kosina wrote: > On Tue, 14 Aug 2012, Russell King wrote: > > > > Actually, Henrik (added to CC) has been doing some latency improvements > > > both for input core in general, and for HID devices as well lately. I > > > still have his patchset in my to-review queue, as I have just came back > > > from offline vacation, but the patch below definitely can't hurt and > > > should significantly lower the time spent in handling the irq for hid > > > device in common situation (i.e. noone listening for debugfs events). > > > > > > Could you please measure how much it helps on your system? > > > > Ok, it looks like it's changed the maximum USB interrupt execution > > time from around 364us to 255us. > > > > If I also do a similar trick with the debug code in hid_input_report() > > then I get down to 212us - iow, something like the patch below. > > Are you testing with kernel that contains b94e3c94aae04 already? That > should cover that case. No - the kernel I'm dealing with is unfortunately based upon v3.5.0-rc5 with many other patches on top (which add support for this platform.) However, I'll pick that commit into this tree. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: