Re: [PATCH 06/10] dir: use expand_to_path() for sparse directories

One more thing:

On Tue, Apr 20, 2021 at 5:52 PM Elijah Newren [off-list ref] wrote:

On Tue, Apr 13, 2021 at 7:01 AM Derrick Stolee via GitGitGadget
[off-list ref] wrote:

quoted

From: Derrick Stolee <redacted>

The recently-implemented expand_to_path() method can supply position
queries a faster response if they are specifically asking for a path
within the sparse cone. Since this is the most-common scenario, this
provides a significant speedup.

Update t1092-sparse-checkout-compatibility.sh to fully ensure that 'git
status' does not expand a sparse index to a full one, even when there
exist untracked files.

The performance test script p2000-sparse-operations.sh demonstrates
that this is the final hole to fill to allow 'git status' to speed up
when using a sparse index:

Test                                  HEAD~1            HEAD
------------------------------------------------------------------------------
2000.4: git status (sparse-index-v3)  1.50(1.43+0.10)   0.04(0.04+0.03) -97.3%
2000.5: git status (sparse-index-v4)  1.50(1.43+0.10)   0.04(0.03+0.04) -97.3%

Um, I'm confused.  In the previous patch you claimed the following speedups:

2000.4: git status (sparse-index-v3)  2.43(2.33+0.14)  0.04(0.05+0.04) -98.4%
2000.5: git status (sparse-index-v4)  2.44(2.35+0.13)  0.05(0.04+0.07) -98.0%

I don't understand why the "Before" for this patch claims 1.50 as the
initial speed, if the "After" for the last patch was 0.04.  Should the
previous commit message have instead claimed:

2000.4: git status (sparse-index-v3)  2.43(2.33+0.14)  1.50(1.43+0.10) -38.3%
2000.5: git status (sparse-index-v4)  2.44(2.35+0.13)  1.50(1.43+0.10) -38.5%

?

quoted

Signed-off-by: Derrick Stolee <redacted>
---
 t/t1092-sparse-checkout-compatibility.sh | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
index 380a085f8ec4..b937d7096afd 100755
--- a/t/t1092-sparse-checkout-compatibility.sh
+++ b/t/t1092-sparse-checkout-compatibility.sh

@@ -456,8 +456,9 @@ test_expect_success 'sparse-index is not expanded' '
        init_repos &&

        rm -f trace2.txt &&
+       echo >>sparse-index/untracked.txt &&
        GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
-               git -C sparse-index status -uno &&
+               git -C sparse-index status &&
        test_region ! index ensure_full_index trace2.txt
 '

--

gitgitgadget

Oh!  So, the previous patch was testing without enumerating untracked
files (because it did those slowly), whereas this one enumerates
untracked files and is still able to achieve the same performance?
This wasn't very clear from the commit message.  Maybe I'm just bad at
reading, but perhaps the commit message could be tweaked slightly to
make this more clear?

Why is the subject of this commit "dir: use expand_to_path() ..." if
it only touches t1092-sparse-checkout-compatibility.sh?