From: Eric Sandeen <sandeen@redhat.com>
To: "Theodore Ts'o" <tytso@mit.edu>
Cc: Eric Whitney <enwlinux@gmail.com>,
linux-ext4@vger.kernel.org, xfs-oss <xfs@oss.sgi.com>
Subject: Re: possible dev branch regression - xfstest 285/1k
Date: Mon, 18 Mar 2013 12:34:59 -0500 [thread overview]
Message-ID: <51475043.4010505@redhat.com> (raw)
In-Reply-To: <20130318170927.GA5639@thunk.org>
On 3/18/13 12:09 PM, Theodore Ts'o wrote:
> On Mon, Mar 18, 2013 at 11:10:51AM -0500, Eric Sandeen wrote:
<previous discussion thread about test 285 SEEK_HOLE test
breaking on ext4 due to change in opportunistic hole-filling
behavior and how to make it work again on ext4, and mention
of sysctl which makes it pass>
>> The test could do this too, right?
>>
>> _need_to_be_root
>>
>> and:
>>
>> if [ "$FSTYP" == "ext4" ]; then
>> ORIG_ZEROOUT_KB=`cat /sys/fs/ext4/$TEST_DEV/extent_max_zeroout_kb`
>> echo 0 > /sys/fs/ext4/$TEST_DEV/extent_max_zeroout_kb
>> fi
>>
>> and put it back to default in _cleanup:
>>
>> echo $ORIG_ZEROOUT_KB > /sys/fs/ext4/$TEST_DEV/extent_max_zeroout_kb
>>
>> That way we'd be testing seek hole correctness w/o being subject to
>> the vagaries in allocator behavior.
>
> Yeah, the question is whether it would be more acceptable to put
> ext4-specific hacks like this into the test, or to modify
> src/seek_sanity_test.c so that it writes the test block-size block
> using pwrite at offset blocksize*42 instead of offset blocksize*10.
That seems like more of an obtuse hack, since it depends on current
default behavior, right?
Explicitly setting the zeroout to 0, with a comment as to why, should
make it clear to the reader of the test I think.
I'll have to look, xfs speculative preallocation fills in holes in
some cases as well, I'm not certain how it behaves on this test.
But we could put in a specific tuning for xfs as well if needed.
If it becomes clear that every fs requires tuning to not opportunistically
fill in holes, then maybe we should make it non-generic, and only support
filesystems we've tested or tuned to work with the testcase.
> I had assumed putting hacks which tweaked sysfs tunables into the
> xfstest script itself would be frowned upon, but if that's considered
> OK, that would be great.
I don't see any real problem with it, myself.
cc: xfs list to see if there are any objections...
-Eric
>
> - Ted
>
WARNING: multiple messages have this Message-ID (diff)
From: Eric Sandeen <sandeen@redhat.com>
To: Theodore Ts'o <tytso@mit.edu>
Cc: xfs-oss <xfs@oss.sgi.com>,
linux-ext4@vger.kernel.org, Eric Whitney <enwlinux@gmail.com>
Subject: Re: possible dev branch regression - xfstest 285/1k
Date: Mon, 18 Mar 2013 12:34:59 -0500 [thread overview]
Message-ID: <51475043.4010505@redhat.com> (raw)
In-Reply-To: <20130318170927.GA5639@thunk.org>
On 3/18/13 12:09 PM, Theodore Ts'o wrote:
> On Mon, Mar 18, 2013 at 11:10:51AM -0500, Eric Sandeen wrote:
<previous discussion thread about test 285 SEEK_HOLE test
breaking on ext4 due to change in opportunistic hole-filling
behavior and how to make it work again on ext4, and mention
of sysctl which makes it pass>
>> The test could do this too, right?
>>
>> _need_to_be_root
>>
>> and:
>>
>> if [ "$FSTYP" == "ext4" ]; then
>> ORIG_ZEROOUT_KB=`cat /sys/fs/ext4/$TEST_DEV/extent_max_zeroout_kb`
>> echo 0 > /sys/fs/ext4/$TEST_DEV/extent_max_zeroout_kb
>> fi
>>
>> and put it back to default in _cleanup:
>>
>> echo $ORIG_ZEROOUT_KB > /sys/fs/ext4/$TEST_DEV/extent_max_zeroout_kb
>>
>> That way we'd be testing seek hole correctness w/o being subject to
>> the vagaries in allocator behavior.
>
> Yeah, the question is whether it would be more acceptable to put
> ext4-specific hacks like this into the test, or to modify
> src/seek_sanity_test.c so that it writes the test block-size block
> using pwrite at offset blocksize*42 instead of offset blocksize*10.
That seems like more of an obtuse hack, since it depends on current
default behavior, right?
Explicitly setting the zeroout to 0, with a comment as to why, should
make it clear to the reader of the test I think.
I'll have to look, xfs speculative preallocation fills in holes in
some cases as well, I'm not certain how it behaves on this test.
But we could put in a specific tuning for xfs as well if needed.
If it becomes clear that every fs requires tuning to not opportunistically
fill in holes, then maybe we should make it non-generic, and only support
filesystems we've tested or tuned to work with the testcase.
> I had assumed putting hacks which tweaked sysfs tunables into the
> xfstest script itself would be frowned upon, but if that's considered
> OK, that would be great.
I don't see any real problem with it, myself.
cc: xfs list to see if there are any objections...
-Eric
>
> - Ted
>
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next prev parent reply other threads:[~2013-03-18 17:35 UTC|newest]
Thread overview: 25+ 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 [this message]
2013-03-18 17:34 ` Eric Sandeen
2013-03-18 20:41 ` Ben Myers
2013-03-18 23:12 ` Dave Chinner
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 2:07 ` Dave Chinner
2013-03-19 1:47 ` 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 2:22 ` Dave Chinner
2013-03-19 2:28 ` Eric Sandeen
2013-03-19 8:50 ` Lukáš Czerner
2013-03-19 8:50 ` Lukáš Czerner
2013-03-17 3:36 ` Eric Whitney
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