[DTrace-devel] [PATCH 2/2] test: Adjust sync timing

[Kris Van Hees]

On Sun, Mar 01, 2026 at 05:39:43PM -0500, eugene.loh at oracle.com wrote:
> From: Eugene Loh <eugene.loh at oracle.com>
> 
> The nusdtprobes test was failing rather consistently on systems with
> very large CPU counts.
> 
> The main problem was that dtrace programs with aggregations take a long
> time to start up on such systems.  In particular, gmap_create_aggs()
> tries to create an aggs_$cpu BPF map for each CPU, spending (in
> measurements on one system) about 0.004 sec for each dt_bpf_map_create()
> and 0.011 sec for each dt_bpf_map_update().  When there are hundreds of
> CPUs, the time to start the job up increases by, for example, 5-6
> seconds.  The test waits for dtrace to start up by checking "-e" on the
> output file, but the aggs_$cpu delay occurs after the file is created.
> 
> Add a BEGIN clause to write to the output file.  Replace the "-e" test
> with "-s".
> 
> The test has a sleep before starting a team of processes.  There is
> perhaps no reason for this wait.  Nonetheless, we leave that sleep,
> simply reducing the time to 1 second.
> 
> There is also a delay between launching processes and tracing them:
> 
>   x dtprobed sees newly launched processes rather quickly
>   x dtrace tries discovery 1x/second
>   x discovery is rather fast
>   x starting a newly discovered probe is ~ 0.011sec (on one system)
> 
> For 40 probes, that last step is about 0.5 sec, but the total "sleep 3"
> in the test before killing the new processes is apparently sufficient.
> 
> Make the corresponding "-e" to "-s" change in similar tests, even if
> they have not shown the failure pattern.
> 
> Signed-off-by: Eugene Loh <eugene.loh at oracle.com>

LGTM.

Reviewed-by: Kris Van Hees <kris.van.hees at oracle.com>

> ---
>  test/unittest/usdt/tst.defer-Z-basic.sh | 10 +++++++---
>  test/unittest/usdt/tst.defer-Z.sh       | 10 +++++++---
>  test/unittest/usdt/tst.defer.sh         | 10 +++++++---
>  test/unittest/usdt/tst.nusdtprobes.sh   | 10 +++++++---
>  4 files changed, 28 insertions(+), 12 deletions(-)
> 
> diff --git a/test/unittest/usdt/tst.defer-Z-basic.sh b/test/unittest/usdt/tst.defer-Z-basic.sh
> index 61adb4601..fad91e5fe 100755
> --- a/test/unittest/usdt/tst.defer-Z-basic.sh
> +++ b/test/unittest/usdt/tst.defer-Z-basic.sh
> @@ -1,7 +1,7 @@
>  #!/bin/bash
>  #
>  # Oracle Linux DTrace.
> -# Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> +# Copyright (c) 2025, 2026, Oracle and/or its affiliates. All rights reserved.
>  # Licensed under the Universal Permissive License v 1.0 as shown at
>  # http://oss.oracle.com/licenses/upl.
>  #
> @@ -22,6 +22,10 @@ cp $trigger main
>  
>  # Start dtrace.
>  $dtrace $dt_flags -Zq -o dtrace.out -n '
> +BEGIN
> +{
> +	printf("BEGIN\n");
> +}
>  testprov*:::foo,
>  testprov*:::bar
>  {
> @@ -33,7 +37,7 @@ dtpid=$!
>  iter=$((timeout / 2))
>  while [ $iter -gt 0 ]; do
>  	sleep 1
> -	if [ -e dtrace.out ]; then
> +	if [ -s dtrace.out ]; then
>  		break
>  	fi
>  	iter=$((iter - 1))
> @@ -79,7 +83,7 @@ if ! diff -q main.out.post main.out.expected; then
>  fi
>  
>  # Regularize the DTrace output, and check it.
> -awk 'NF > 0 { map[$2 " " $1]++; }
> +awk 'NF > 1 { map[$2 " " $1]++; }
>       END { for (i in map) printf "%s %d\n", i, map[i]; }' dtrace.out > dtrace.out.post
>  
>  echo "$tpid main:bar 10" > dtrace.out.expected
> diff --git a/test/unittest/usdt/tst.defer-Z.sh b/test/unittest/usdt/tst.defer-Z.sh
> index ff2c5cbf1..db49cd583 100755
> --- a/test/unittest/usdt/tst.defer-Z.sh
> +++ b/test/unittest/usdt/tst.defer-Z.sh
> @@ -1,7 +1,7 @@
>  #!/bin/bash
>  #
>  # Oracle Linux DTrace.
> -# Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
> +# Copyright (c) 2024, 2026, Oracle and/or its affiliates. All rights reserved.
>  # Licensed under the Universal Permissive License v 1.0 as shown at
>  # http://oss.oracle.com/licenses/upl.
>  #
> @@ -29,6 +29,10 @@ cp $trigger main
>  # Start dtrace.
>  
>  $dtrace $dt_flags -Zwq -o dtrace.out -n '
> +BEGIN
> +{
> +	printf("BEGIN\n");
> +}
>  testprov*:::foo
>  {
>  	raise(SIGUSR1);
> @@ -51,7 +55,7 @@ dtpid=$!
>  iter=$((timeout / 2))
>  while [ $iter -gt 0 ]; do
>  	sleep 1
> -	if [ -e dtrace.out ]; then
> +	if [ -s dtrace.out ]; then
>  		break
>  	fi
>  	iter=$((iter - 1))
> @@ -128,7 +132,7 @@ done
>  # Check the dtrace output.
>  
>  #     regularize the dtrace output
> -awk 'NF != 0 { print $1, $2, $3 }' dtrace.out | sort > dtrace.out.post
> +awk 'NF == 3 { print $1, $2, $3 }' dtrace.out | sort > dtrace.out.post
>  
>  #     determine what to expect
>  
> diff --git a/test/unittest/usdt/tst.defer.sh b/test/unittest/usdt/tst.defer.sh
> index 073af12d5..a1c29571c 100755
> --- a/test/unittest/usdt/tst.defer.sh
> +++ b/test/unittest/usdt/tst.defer.sh
> @@ -1,7 +1,7 @@
>  #!/bin/bash
>  #
>  # Oracle Linux DTrace.
> -# Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
> +# Copyright (c) 2024, 2026, Oracle and/or its affiliates. All rights reserved.
>  # Licensed under the Universal Permissive License v 1.0 as shown at
>  # http://oss.oracle.com/licenses/upl.
>  #
> @@ -39,6 +39,10 @@ lastdigit=$((${pids[0]} % 10))
>  # Start dtrace.
>  
>  $dtrace $dt_flags -wq -o dtrace.out -n '
> +BEGIN
> +{
> +	printf("BEGIN\n");
> +}
>  testprov*:::foo
>  {
>  	raise(SIGUSR1);
> @@ -57,7 +61,7 @@ dtpid=$!
>  iter=$((timeout / 2))
>  while [ $iter -gt 0 ]; do
>  	sleep 1
> -	if [ -e dtrace.out ]; then
> +	if [ -s dtrace.out ]; then
>  		break
>  	fi
>  	iter=$((iter - 1))
> @@ -135,7 +139,7 @@ done
>  # Check the dtrace output.
>  
>  #     regularize the dtrace output
> -awk 'NF != 0 { print $1, $2, $3 }' dtrace.out | sort > dtrace.out.post
> +awk 'NF == 3 { print $1, $2, $3 }' dtrace.out | sort > dtrace.out.post
>  
>  #     determine what to expect
>  
> diff --git a/test/unittest/usdt/tst.nusdtprobes.sh b/test/unittest/usdt/tst.nusdtprobes.sh
> index 93c56e382..5e3a49724 100755
> --- a/test/unittest/usdt/tst.nusdtprobes.sh
> +++ b/test/unittest/usdt/tst.nusdtprobes.sh
> @@ -1,7 +1,7 @@
>  #!/bin/bash
>  #
>  # Oracle Linux DTrace.
> -# Copyright (c) 2024, 2025, Oracle and/or its affiliates. All rights reserved.
> +# Copyright (c) 2024, 2026, Oracle and/or its affiliates. All rights reserved.
>  # Licensed under the Universal Permissive License v 1.0 as shown at
>  # http://oss.oracle.com/licenses/upl.
>  #
> @@ -100,6 +100,10 @@ for nusdt in "" "-xnusdtprobes=40" "-xnusdtprobes=39"; do
>  
>  	rm -f dtrace.out
>  	$dtrace $dt_flags $nusdt -Zq -o dtrace.out -n '
> +	BEGIN
> +	{
> +		printf("BEGIN\n");
> +	}
>  	testprov*:::
>  	{
>  		@[probeprov, probemod, probefunc, probename] = count();
> @@ -111,7 +115,7 @@ for nusdt in "" "-xnusdtprobes=40" "-xnusdtprobes=39"; do
>  	iter=$((timeout / 4))
>  	while [ $iter -gt 0 ]; do
>  		sleep 1
> -		if [ -e dtrace.out ]; then
> +		if [ -s dtrace.out ]; then
>  			break
>  		fi
>  		iter=$((iter - 1))
> @@ -127,7 +131,7 @@ for nusdt in "" "-xnusdtprobes=40" "-xnusdtprobes=39"; do
>  	rm -f check.txt
>  	for (( iteam = 0; iteam < $nteams; iteam++ )); do
>  		# Start the team, writing out expected output.
> -		sleep 2
> +		sleep 1
>  		for (( immbr = 0; immbr < $nmmbrs; immbr++ )); do
>  			./main &
>  			pids[$immbr]=$!
> -- 
> 2.47.3
>