From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hurley Subject: Re: [PATCH tty-next 7/7] n_tty: trace input/read flow control Date: Tue, 26 Nov 2013 08:00:35 -0500 Message-ID: <52949B73.3000206@hurleysoftware.com> References: <1385135965-4235-1-git-send-email-peter@hurleysoftware.com> <1385135965-4235-8-git-send-email-peter@hurleysoftware.com> <20131124002513.0a806665@alan.etchedpixels.co.uk> <529166C0.8040001@hurleysoftware.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mailout32.mail01.mtsvc.net ([216.70.64.70]:57742 "EHLO n23.mail01.mtsvc.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751083Ab3KZNAk (ORCPT ); Tue, 26 Nov 2013 08:00:40 -0500 In-Reply-To: <529166C0.8040001@hurleysoftware.com> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Greg Kroah-Hartman Cc: One Thousand Gnomes , Jiri Slaby , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org On 11/23/2013 09:38 PM, Peter Hurley wrote: > On 11/23/2013 07:25 PM, One Thousand Gnomes wrote: >> On Fri, 22 Nov 2013 10:59:25 -0500 >> Peter Hurley wrote: >> >>> Instrument .receive_buf() and read() paths with trace_printk's >>> to aid in debugging flow control changes. >> >> tty devices have a device, we have a dev_dbg() layer. The old tty trace >> predates this but there isn't really any excuse for not using it now that >> I can see ? > > I was using the ftrace facility because it has significantly less performance > impact than printk (which was an important factor while debugging flow control > problems). > > That said, I could further macro-ize n_tty_trace() with selectable facility > (which would be useful when debugging problems that end in cpu death). Greg, I don't really mind if you don't want to take this patch; it is useful but it does clutter up the code. Regards, Peter Hurley