[LTP] [PATCH] ltp-aiodio.part4: Run DIT000 with only 1 reader process

[LTP] [PATCH] ltp-aiodio.part4: Run DIT000 with only 1 reader process

[Martin Doucha]

New changes in real-time kernel patchset give high priority to direct I/O
readers and may cause writes to block indefinitely if there are too many
reader processes running in parallel. Reduce the number of reader processes
in DIT000 to 1 which was the dio_truncate default before rewrite to new API.

Signed-off-by: Martin Doucha <mdoucha@suse.cz>
---
 runtest/ltp-aiodio.part4 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/runtest/ltp-aiodio.part4 b/runtest/ltp-aiodio.part4
index d88c27a83..c31bef934 100644
--- a/runtest/ltp-aiodio.part4
+++ b/runtest/ltp-aiodio.part4
@@ -56,7 +56,7 @@ ADI007 dio_append
 ADI008 dio_append
 ADI009 dio_append
 #Running dio_truncate
-DIT000 dio_truncate
+DIT000 dio_truncate -n 1
 DIT001 dio_truncate
 DIT002 dio_truncate
 #Running dio_read
-- 
2.39.0


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Re: [LTP] [PATCH] ltp-aiodio.part4: Run DIT000 with only 1 reader process

[Petr Vorel]

Hi Martin,

> New changes in real-time kernel patchset give high priority to direct I/O
> readers and may cause writes to block indefinitely if there are too many
> reader processes running in parallel. Reduce the number of reader processes
> in DIT000 to 1 which was the dio_truncate default before rewrite to new API.

Correct, before 7a3741679d it was 1:

-int main(void)
+static void run(void)
 {
-	char filename[PATH_MAX];
-	int pid[NUM_CHILDREN];
-	int num_children = 1;
+	char *filename = "file";
+	int filesize = FILE_SIZE;
+	int num_children = NUM_CHILDREN;

> +++ b/runtest/ltp-aiodio.part4
> @@ -56,7 +56,7 @@ ADI007 dio_append
>  ADI008 dio_append
>  ADI009 dio_append
>  #Running dio_truncate
> -DIT000 dio_truncate
> +DIT000 dio_truncate -n 1
>  DIT001 dio_truncate
>  DIT002 dio_truncate
>  #Running dio_read

But I wonder why changing just the first dio_truncate will fix it
(obviously not). Could we detect RT and force -n 1 for it?
(utsname.version should have "PREEMPT RT"). Obviously only from version which
got affected.

Kind regards,
Petr


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Re: [LTP] [PATCH] ltp-aiodio.part4: Run DIT000 with only 1 reader process

[Martin Doucha]

On 05. 01. 23 16:38, Petr Vorel wrote:
> But I wonder why changing just the first dio_truncate will fix it
> (obviously not). Could we detect RT and force -n 1 for it?
> (utsname.version should have "PREEMPT RT"). Obviously only from version which
> got affected.

It'll fix only one of the three tests. But I like having some direct I/O 
stress tests for regular kernels so I've modified only one dio_truncate 
instance. The other can be skipped manually on RT kernels.

But let's add a warning to dio_truncate if it's running on RT kernel 
with too many children so that users know that the failure is sometimes 
expected.

-- 
Martin Doucha   mdoucha@suse.cz
QA Engineer for Software Maintenance
SUSE LINUX, s.r.o.
CORSO IIa
Krizikova 148/34
186 00 Prague 8
Czech Republic


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Re: [LTP] [PATCH] ltp-aiodio.part4: Run DIT000 with only 1 reader process

[Petr Vorel]

Hi Martin,

> On 05. 01. 23 16:38, Petr Vorel wrote:
> > But I wonder why changing just the first dio_truncate will fix it
> > (obviously not). Could we detect RT and force -n 1 for it?
> > (utsname.version should have "PREEMPT RT"). Obviously only from version which
> > got affected.

> It'll fix only one of the three tests. But I like having some direct I/O
> stress tests for regular kernels so I've modified only one dio_truncate
> instance. The other can be skipped manually on RT kernels.

Make sense.

> But let's add a warning to dio_truncate if it's running on RT kernel with
> too many children so that users know that the failure is sometimes expected.

Thank you!

Reviewed-by: Petr Vorel <pvorel@suse.cz>

Kind regards,
Petr

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