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

Elijah Newren [off-list ref] writes:

On Tue, Jul 13, 2021 at 10:10 AM Jeff Hostetler [off-list ref] wrote:

quoted

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.

Yeah, test_seq is pretty bad; it's just a loop in shell.  Is there a
'seq' on windows, and does using it instead of test_seq make things
faster with Ævar's suggested command?

Unless I am misreading Jeff's message, I do not think that makes
sense.  Counting to 10000 in shell loop is trivial (0.2 seconds),
but letting touch invoked 10000 times to create (or smudge mtime of,
but I suspect that is not what is going on here) 10000 files takes
3.1 seconds, and of course a native binary that creates 10000 files
with a single invocation would be faster.

I'd really like to modify test_seq to use seq when it's available and
fall back to the looping-in-shell when we need to for various
platforms.

So, if I am reading Jeff correctly, that optimizes something that is
not a bottleneck.

Maybe it'd even make sense to write a 'test-tool seq' and make
test_seq use that just so we can rip out that super lame shell
looping.

On Tue, Jul 13, 2021 at 10:47 AM Junio C Hamano [off-list ref] wrote:

Elijah Newren [off-list ref] writes:

quoted

On Tue, Jul 13, 2021 at 10:10 AM Jeff Hostetler [off-list ref] wrote:

quoted

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.

Yeah, test_seq is pretty bad; it's just a loop in shell.  Is there a
'seq' on windows, and does using it instead of test_seq make things
faster with Ævar's suggested command?

Unless I am misreading Jeff's message, I do not think that makes
sense.  Counting to 10000 in shell loop is trivial (0.2 seconds),
but letting touch invoked 10000 times to create (or smudge mtime of,
but I suspect that is not what is going on here) 10000 files takes
3.1 seconds, and of course a native binary that creates 10000 files
with a single invocation would be faster.

quoted

I'd really like to modify test_seq to use seq when it's available and
fall back to the looping-in-shell when we need to for various
platforms.

So, if I am reading Jeff correctly, that optimizes something that is
not a bottleneck.

Oh, indeed.  Sorry, I misread.