Date: Thu, 26 Mar 2009 16:44:31 +0100
From: Jens Axboe <jens.axboe@oracle.com>
To: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>, Li Zefan <lizf@cn.fujitsu.com>,
       Steven Rostedt <rostedt@goodmis.org>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/3] blktrace: fix the original blktrace
Message-ID: <20090326154431.GG27476@kernel.dk>
References: <49C9F700.9070609@cn.fujitsu.com> <49C9F796.9040503@cn.fujitsu.com> <20090325101451.GK2341@elte.hu> <20090325101747.GL27476@kernel.dk> <49CAE4CB.3050000@cn.fujitsu.com> <20090326082939.GF27476@kernel.dk> <20090326133732.GA14822@elte.hu> <20090326151403.GH10928@ghostprotocols.net>
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On Thu, Mar 26 2009, Arnaldo Carvalho de Melo wrote:
> Em Thu, Mar 26, 2009 at 02:37:32PM +0100, Ingo Molnar escreveu:
> > 
> > * Jens Axboe <jens.axboe@oracle.com> wrote:
> > 
> > > > One is introduced by "block: get rid of the manual directory counting in blktrace"
> > > > (f48fc4d32e24c0b6a18aad30305d819bcc68c049). Two are "blktrace: port to tracepoints"
> > > > (5f3ea37c7716db4e894a480e0c18b24399595b6b). Both commits are in mainline.
> > > > 
> > > > Since 2 of the bugs will rarely happen in real-life, and the 3rd 
> > > > one is a small issue, and we were so close to the release of 
> > > > .29, so I sent the fixes for -tip tree but not mainline. But if 
> > > > we are going merge tip/blktrace to .31, I guess it's better to 
> > > > merge that 3 fixes to .30?
> > > 
> > > Since you are the person that worked on it most lately, your 
> > > opinion matters the most. What do you think, is it ready for 
> > > 2.6.30 or should it wait for .31?
> > 
> > Yeah. Li, Arnaldo, what do you think?
> > 
> > Delaying them would be quite painful at this stage though - the 
> > blktrace plugin conversion was done with (ahem) your initial support 
> > so the commits got (foolishly, in hindsight ;-) interwoven into 300 
> > commits of the 2.6.30 tracing tree.
> > 
> > Delaying them would also be technically baseless - there are no 
> > known regressions or bugs in this code. (If you know about bugs then 
> > please speak up so we can fix them! ;-)
> > 
> > At this last minute stage we can do two things: merge it now or if 
> > you NAK it then we'll rebase the last ~2 months of the tracing tree 
> > with hundreds of commits (sigh), destroy its true history in the 
> > process and eradicate the blktrace bits.
> > 
> > I'd like to avoid the second option if possible as it destroys real 
> > value (these changes are really nice improvements, a lot of work 
> > went into them and there's no open regressions so i can see no 
> > objective reason why they couldnt go upstream now) but it's your 
> > choice really, you maintain block/* :-)
> 
> Well, after this set of fixes by Li the only problem I'm aware of is the
> __trace_note_message, that is using ftrace_vprintk, that I didn't notice
> because I wasn't using CFQ when developing it, and that gets the output
> of the _ftrace_ plugin wedged, but that doesn't affect normal blktrace
> operation.
> 
> I'll try to get that fixed somehow today, other than that I'm not aware
> of any other problem, so I think it could get into 2.6.30 on the premise
> that normal blktrace operation is as stable as before and that the
> ftrace plugin is recent work and may still need some fixes.

Well, judging whether it is as stable as before is exactly what is asked
of you and Li :-). So which is it?

-- 
Jens Axboe

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