Re: [PATCH v3 24/34] t/perf/p7519: speed up test using "test-tool touch"

On Tue, Jul 13 2021, Jeff Hostetler wrote:

On 7/1/21 7:09 PM, Ævar Arnfjörð Bjarmason wrote:

quoted

On Thu, Jul 01 2021, Jeff Hostetler via GitGitGadget wrote:

quoted

From: Jeff Hostetler <redacted>

Change p7519 to use a single "test-tool touch" command to update
the mtime on a series of (thousands) files instead of invoking
thousands of commands to update a single file.

This is primarily for Windows where process creation is so
very slow and reduces the test run time by minutes.

Signed-off-by: Jeff Hostetler <redacted>
---
  t/perf/p7519-fsmonitor.sh | 14 ++++++--------
  1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/t/perf/p7519-fsmonitor.sh b/t/perf/p7519-fsmonitor.sh
index 5eb5044a103..f74e6014a0a 100755
--- a/t/perf/p7519-fsmonitor.sh
+++ b/t/perf/p7519-fsmonitor.sh

@@ -119,10 +119,11 @@ test_expect_success "one time repo setup" '
  	fi &&
    	mkdir 1_file 10_files 100_files 1000_files 10000_files &&
-	for i in $(test_seq 1 10); do touch 10_files/$i; done &&
-	for i in $(test_seq 1 100); do touch 100_files/$i; done &&
-	for i in $(test_seq 1 1000); do touch 1000_files/$i; done &&
-	for i in $(test_seq 1 10000); do touch 10000_files/$i; done &&
+	test-tool touch sequence --pattern="10_files/%d" --start=1 --count=10 &&
+	test-tool touch sequence --pattern="100_files/%d" --start=1 --count=100 &&
+	test-tool touch sequence --pattern="1000_files/%d" --start=1 --count=1000 &&
+	test-tool touch sequence --pattern="10000_files/%d" --start=1 --count=10000 &&
+
  	git add 1_file 10_files 100_files 1000_files 10000_files &&
  	git commit -qm "Add files" &&
  @@ -200,15 +201,12 @@ test_fsmonitor_suite() {
  	# Update the mtimes on upto 100k files to make status think
  	# that they are dirty.  For simplicity, omit any files with
  	# LFs (i.e. anything that ls-files thinks it needs to dquote).
-	# Then fully backslash-quote the paths to capture any
-	# whitespace so that they pass thru xargs properly.
  	#
  	test_perf_w_drop_caches "status (dirty) ($DESC)" '
  		git ls-files | \
  			head -100000 | \
  			grep -v \" | \
-			sed '\''s/\(.\)/\\\1/g'\'' | \
-			xargs test-tool chmtime -300 &&
+			test-tool touch stdin &&
  		git status
  	'

Did you try to replace this with some variant of:
     test_seq 1 10000 | xargs touch
Which (depending on your xargs version) would invoke "touch"
commands
with however many argv items it thinks you can handle.

a quick test on my Windows machine shows that

	test_seq 1 10000 | xargs touch

takes 3.1 seconds.

just a simple

	test_seq 1 10000 >/dev/null

take 0.2 seconds.

using my test-tool helper cuts that time in half.

There's what Elijah mentioned about test_seq, so maybe it's just that.

But what I was suggesting was using the xargs mode where it does N
arguments at a time.

Does this work for you, and does it cause xargs to invoke "touch" with
the relevant N number of arguments, and does it help with the
performance?

    test_seq 1 10000 | xargs touch
    test_seq 1 10000 | xargs -n 10 touch
    test_seq 1 10000 | xargs -n 100 touch
    test_seq 1 10000 | xargs -n 1000 touch

etc.

Also I didn't notice this before, but the -300 part of "chmtime -300"
was redundant before then? I.e. you're implicitly changing it to "=+0"
instead with your "touch" helper, are you not?