From: Eric Sandeen <sandeen@sandeen.net>
To: Theodore Ts'o <tytso@mit.edu>
Cc: Eric Sandeen <sandeen@redhat.com>,
Eric Whitney <enwlinux@gmail.com>, xfs-oss <xfs@oss.sgi.com>,
Ben Myers <bpm@sgi.com>,
linux-ext4@vger.kernel.org
Subject: Re: possible dev branch regression - xfstest 285/1k
Date: Mon, 18 Mar 2013 21:28:22 -0500 [thread overview]
Message-ID: <5147CD46.1090205@sandeen.net> (raw)
In-Reply-To: <20130319020056.GC4660@thunk.org>
On 3/18/13 9:00 PM, Theodore Ts'o wrote:
> On Tue, Mar 19, 2013 at 12:47:18PM +1100, Dave Chinner wrote:
>> Sorry about this - I've mixed up my threads about ext4 having
>> problems with zero-out being re-enabled. I thought this was a
>> cross-post of the 218 issue....
>>
>> However, the same reasoning can be applied to 285 - the file sizes,
>> the size of the holes and the size of the data is all completely
>> arbitrary. If we make the holes in the files larger, then the
>> zero-out problem simply goes away.
>
> Right. That was my observation. We can either make the holes larger,
> by changing:
>
> pwrite(fd, buf, bufsize, bufsize*10);
>
> to
>
> pwrite(fd, buf, bufsize, bufsize*42);
>
> ... and then changing the expected values returned by
> SEEK_HOLE/SEEK_DATA. (By the way; this only matters when we are
> testing 1k blocks; if we are using a 4k block size in ext4, the test
> currently passes.)
>
> Or we could set some ext4-specific tuning parameters into the #218
285! :)
> shell script, if the file system in question was ext4.
>
> I had assumed that folks would prefer making the holes larger, but
> Eric seemed to prefer the second choice as a better one.
Ok, after the discussion I'm convinced too. Stretching out the allocation
to avoid fill-in probably makes sense. But maybe not "42" -
how about something much larger, so that any "reasonable" filesystem
wouldn't even consider zeroing the range in between?
-Eric
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next prev parent reply other threads:[~2013-03-19 2:28 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-15 22:28 possible dev branch regression - xfstest 285/1k Eric Whitney
2013-03-16 2:32 ` Zheng Liu
2013-03-16 15:09 ` Zheng Liu
2013-03-17 3:06 ` Theodore Ts'o
2013-03-17 6:13 ` Zheng Liu
2013-03-18 16:10 ` Eric Sandeen
2013-03-18 16:54 ` gnehzuil.liu
2013-03-18 17:09 ` Theodore Ts'o
2013-03-18 17:34 ` Eric Sandeen
2013-03-18 20:41 ` Ben Myers
2013-03-18 23:12 ` Dave Chinner
2013-03-19 1:40 ` Theodore Ts'o
2013-03-19 2:07 ` Dave Chinner
2013-03-19 1:47 ` Dave Chinner
2013-03-19 2:00 ` Theodore Ts'o
2013-03-19 2:22 ` Dave Chinner
2013-03-19 2:28 ` Eric Sandeen [this message]
2013-03-19 8:50 ` Lukáš Czerner
2013-03-17 3:36 ` Eric Whitney
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