From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S932080Ab2GXU20 (ORCPT <rfc822;w@1wt.eu>);
	Tue, 24 Jul 2012 16:28:26 -0400
Received: from mail.skyhub.de ([78.46.96.112]:58450 "EHLO mail.skyhub.de"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1755738Ab2GXU2Z (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Tue, 24 Jul 2012 16:28:25 -0400
Date: Tue, 24 Jul 2012 22:28:20 +0200
From: Borislav Petkov <bp@alien8.de>
To: =?utf-8?B?SsO2cm4=?= Engel <joern@logfs.org>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org,
        Jeff Moyer <jmoyer@redhat.com>, Steve Hodgson <steve@purestorage.com>
Subject: Re: [PATCH] add blockconsole version 1.1
Message-ID: <20120724202820.GA5167@liondog.tnic>
Mail-Followup-To: Borislav Petkov <bp@alien8.de>,
	=?utf-8?B?SsO2cm4=?= Engel <joern@logfs.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, Jeff Moyer <jmoyer@redhat.com>,
	Steve Hodgson <steve@purestorage.com>
References: <20120713130336.GC10298@x1.osrc.amd.com>
 <20120713162009.GA10268@logfs.org>
 <20120716124614.GA19497@x1.osrc.amd.com>
 <20120718185335.GA1771@logfs.org>
 <20120718214520.GA14067@liondog.tnic>
 <20120723200459.GD17767@logfs.org>
 <20120724154218.GB13753@x1.osrc.amd.com>
 <20120724145334.GB24954@logfs.org>
 <20120724162546.GC13753@x1.osrc.amd.com>
 <20120724175232.GC24954@logfs.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20120724175232.GC24954@logfs.org>
User-Agent: Mutt/1.5.21 (2010-09-15)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Tue, Jul 24, 2012 at 01:52:32PM -0400, Jörn Engel wrote:
> On Tue, 24 July 2012 18:25:47 +0200, Borislav Petkov wrote:
> > > The advantage should be better robustness, in particular when dealing
> > > with cheap flash devices.
> > 
> > In the sense that we flush the current sector after one second the
> > latest so that we can lose as small amount of data as possible if the
> > system crashes right at that point?
> 
> In the sense that cheap devices don't always handle rewrites of the
> same sector well.  Often this results in the entire erase block being
> rewritten, causing bad performance and wear-out.  Many cheap devices
> aren't real block devices.  They are barely good enough to support
> FAT and may die near-instantly with a different write pattern.
> Blockconsole assumes utter crap as an underlying device.
> 
> The timer mainly ensures that, on a quiet system, those two lines of
> output from half an hour ago actually make it to the device
> eventually.  In the case of a crash, the panic notifier is supposed to
> do the same for those messages you _really_ care about.
> 
> > Ok, I see what you mean. I see a red line in vim here. Ok, good to know,
> > maybe this feature with the empty lines could be in the docs too so
> > people don't ask that question again?
> 
> Last paragraph. ;)
> 
> > Or you issue a tag instead of an empty line like so:
> > 
> > [   10.498422] console [bcon0] enabled
> > [   10.499899] blockconsole: now logging to /dev/sdc at 1
> > [   10.594791] usb 5-2: new full-speed USB device number 3 using ohci_hcd
> > <<LOG timeout of 1sec>>
> > [   12.665911] xhci_hcd 0000:00:10.0: xHCI Host Controller
> > [   12.668469] xhci_hcd 0000:00:10.0: new USB bus registered, assigned bus number 6
> > 
> > which explains everything.
> 
> That would only work if you have at least 26 bytes to pad.  Bunch of
> spaces with a newline works for any value between 0 and 512.

Ok, thanks for taking the time to explain this - very interesting stuff.

So, as far as I'm concerned blockconsole is ready for shipping! 8-)

-- 
Regards/Gruss,
    Boris.