From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932613AbaDBQnz (ORCPT ); Wed, 2 Apr 2014 12:43:55 -0400 Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:58335 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932335AbaDBQnw (ORCPT ); Wed, 2 Apr 2014 12:43:52 -0400 Date: Wed, 2 Apr 2014 17:43:42 +0100 From: One Thousand Gnomes To: Jiri Slaby Cc: gregkh@linuxfoundation.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] serial: 8250, disable "too much work" messages Message-ID: <20140402174342.1f78a39e@alan.etchedpixels.co.uk> In-Reply-To: <533BDC4F.3060903@suse.cz> References: <1396352220-5031-1-git-send-email-jslaby@suse.cz> <20140401144057.63b3ceb5@alan.etchedpixels.co.uk> <533BDC4F.3060903@suse.cz> Organization: Intel Corporation X-Mailer: Claws Mail 3.8.1 (GTK+ 2.24.20; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > So, according to Takashi's measurements, we would need over 15000 loops > on a single port. Of course, this value is highly dependent on a system. > On my system, it is like 7 times lower (2100). And it lasts ~300ms here. > > I suppose a limit like 32k loops is way too much and I just should go > and implement the polling. Or what about adding inter-character sleeps > to qemu to correspond to the speed? I can do that too, but I am not sure > if limiting the throughput will be accepted by them. The other option would be to detect qemu as a buggy uart, log a warning and ignore the test on it. I think polling might be better, and that would probably fix hang cases on real buggy uarts where right now we sometimes keel over.