Re: [PATCH v1] generic/476: requires 27GB scratch size

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

On Thu, Jul 21, 2022 at 10:29:59AM +0800, bxue@redhat.com wrote:
> From: Boyang Xue <bxue@redhat.com>
> 
> The test requires larger scratch dev size when running on top of NFS other
> than ext4 and xfs. It requires at least 27GB in my test. Without this
> requirement, the test run never finishes on NFS, leaving 100% scratch disk
> space use.

> Signed-off-by: Boyang Xue <bxue@redhat.com>
> ---
> Hi,
> 
> I find generic/476 easily goes into an infinite run on top of NFS. When it

Infinite?  It's only supposed to start 25000*nr_cpus*TIME_FACTOR
operations, so it /should/ conclude eventually.  That includes driving
the filesystem completel out of space, but there ought to be enough
unlink/rmdir/truncate calls to free up space every now and then...

> happens, the common pattern is 100% disk space use of SCRATCH_MNT, and
> `nfsiostat` shows 50% write error on SCRATCH_MNT. When I run it with a large
> enough SCRATCH_MNT, the problem disappears. So I post this patch to add the size
> requirement.
> 
> Please help review this patch. Thanks!
> 
> -Boyang
> 
>  tests/generic/476 | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tests/generic/476 b/tests/generic/476
> index 212373d1..dcc7c3da 100755
> --- a/tests/generic/476
> +++ b/tests/generic/476
> @@ -24,6 +24,7 @@ _cleanup()
>  _supported_fs generic
>  
>  _require_scratch
> +_require_scratch_size $((27 * 1024 * 1024)) # 27GB

...so IDGI, this test works as intended.  Are you saying that NFS
command overhead is so high that this test takes too long?

--D

>  _require_command "$KILLALL_PROG" "killall"
>  
>  echo "Silence is golden."
> -- 
> 2.27.0
>