Re: [PATCH 3/8] generic/192: fix spurious timeout

["Darrick J. Wong" <djwong@kernel.org>]

On Tue, Feb 27, 2024 at 12:23:46PM +0800, Zorro Lang wrote:
> On Mon, Feb 26, 2024 at 06:01:19PM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > I have a theory that when the nfs server that hosts the root fs for my
> > testing VMs gets backed up, it can take a while for path resolution and
> > loading of echo, cat, or tee to finish.  That delays the test enough to
> > result in:
> > 
> > --- /tmp/fstests/tests/generic/192.out	2023-11-29 15:40:52.715517458 -0800
> > +++ /var/tmp/fstests/generic/192.out.bad	2023-12-15 21:28:02.860000000 -0800
> > @@ -1,5 +1,6 @@
> >  QA output created by 192
> >  sleep for 5 seconds
> >  test
> > -delta1 is in range
> > +delta1 has value of 12
> > +delta1 is NOT in range 5 .. 7
> >  delta2 is in range
> 
> 
> 
> > 
> > Therefore, invoke all these utilities with --help before the critical
> > section to make sure they're all in memory.
> > 
> > Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> > ---
> 
> This patch makes sense to me,
> Reviewed-by: Zorro Lang <zlang@redhat.com>
> 
> Just better to give 1 or 2 whitespaces to diff output message (especially the
> lines with "+") in commit log :) I always need to change that manually before
> merge the patch :-D

Oh, you mean indenting the diff output in the commit message?

Yeah, I'll try to remember that from now on:

I have a theory that when the nfs server that hosts the root fs for my
testing VMs gets backed up, it can take a while for path resolution and
loading of echo, cat, or tee to finish.  That delays the test enough to
result in:

  --- /tmp/fstests/tests/generic/192.out	2023-11-29 15:40:52.715517458 -0800
  +++ /var/tmp/fstests/generic/192.out.bad	2023-12-15 21:28:02.860000000 -0800
  @@ -1,5 +1,6 @@
   QA output created by 192
   sleep for 5 seconds
   test
  -delta1 is in range
  +delta1 has value of 12
  +delta1 is NOT in range 5 .. 7
   delta2 is in range

Therefore, invoke all these utilities with --help before the critical
section to make sure they're all in memory.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>

--D

> Thanks,
> Zorro
> 
> >  tests/generic/192 |   16 +++++++++++++---
> >  1 file changed, 13 insertions(+), 3 deletions(-)
> > 
> > 
> > diff --git a/tests/generic/192 b/tests/generic/192
> > index 0d3cd03b4b..2825486635 100755
> > --- a/tests/generic/192
> > +++ b/tests/generic/192
> > @@ -29,17 +29,27 @@ delay=5
> >  testfile=$TEST_DIR/testfile
> >  rm -f $testfile
> >  
> > +# Preload every binary used between sampling time1 and time2 so that loading
> > +# them has minimal overhead even if the root fs is hosted over a slow network.
> > +# Also don't put pipe and tee creation in that critical section.
> > +for i in echo stat sleep cat; do
> > +	$i --help &>/dev/null
> > +done
> > +
> >  echo test >$testfile
> > -time1=`_access_time $testfile | tee -a $seqres.full`
> > +time1=`_access_time $testfile`
> > +echo $time1 >> $seqres.full
> >  
> >  echo "sleep for $delay seconds"
> >  sleep $delay # sleep to allow time to move on for access
> >  cat $testfile
> > -time2=`_access_time $testfile | tee -a $seqres.full`
> > +time2=`_access_time $testfile`
> > +echo $time2 >> $seqres.full
> >  
> >  cd /
> >  _test_cycle_mount
> > -time3=`_access_time $testfile | tee -a $seqres.full`
> > +time3=`_access_time $testfile`
> > +echo $time3 >> $seqres.full
> >  
> >  delta1=`expr $time2 - $time1`
> >  delta2=`expr $time3 - $time1`
> > 
> 
>