Re: Slow I/O on USB media

From: Andrea Vai <andrea.vai@unipv.it>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Greg KH <gregkh@linuxfoundation.org>, linux-usb@vger.kernel.org
Subject: Re: Slow I/O on USB media
Date: Mon, 17 Jun 2019 18:34:23 +0200	[thread overview]
Message-ID: <6ff3332b940f02d988d9bc578c1c293e8424e439.camel@unipv.it> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1906171202580.1738-100000@iolanthe.rowland.org>

Il giorno lun, 17/06/2019 alle 12.14 -0400, Alan Stern ha scritto:
> On Mon, 17 Jun 2019, Andrea Vai wrote:
> 
> > [...]
> > 
> > That happened ALL times, so I never encountered a kernel that made
> me
> > say "git bisect good".
> 
> Really?  That strongly suggests that the 4.20 kernel also should
> have
> been marked bad.  Did you really test it exactly the same way as all
> the others?  That is, did you go through the entire procedure
> starting
> with "git checkout v4.20", then running the build script, then the
> reboot and "uname -a", and then the test script?

well, honestly, no, because (sigh) I didn't know the "git checkout"
command, sorry. I started with building 4.20 from the source
downloaded with

 wget https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/snapshot/linux-4.20.tar.gz

, then said "git bisect good v4.20".

Is this different from "git checkout v4.20"? I hope it is, so we have
found the mistake I have done.

> Or did you just run a few tests with the Fedora 4.20.13 kernel and
> assume that the results would be the same as those?

no, I am sure I have never used the Fedora kernel(s) during the last
bisect process.

> 
> > [...]
> 
> If _all_ the kernels you built and tested were bad then you
> probably 
> did not start the bisection from the right commit.

so, I hope this is true :-)

> 
> > By the way, I noticed an error ("Unexpected system error")
> reported
> > sometimes by the Fedora ABRT tool, that states "this is not a
> software
> > bug, the kernel log indicates it is a hardware error", or
> something
> > similar (sorry, at the moment I don't know exactly where to find
> it).
> 
> Did you look in the kernel log?

Yes I did, but I didn't took care about it very much. I will do it
again, and report here, if as far as I understand you are saying that
it could be useful.

> 
> > [...]
> 
> Compare the mainstream 4.20 kernel with the Fedora 4.20.13 kernel.  
> Also, maybe compare the mainstream 4.20.13 with Fedora's 4.20.13.

Sorry, what do you mean here by "compare"? And what is the
"mainstream"? If the mainstream is the one I got with wget, and if
"compare" means "see if they behave differently", so I have already
done it and they are both "good".

Thank you,
Andrea