Re: [PATCH v2] sphinx: kernel_abi: fix performance regression with O=<dir>

[Akira Yokosawa <akiyks@gmail.com>]

On Thu, 17 Jul 2025 13:37:19 +0200, Mauro Carvalho Chehab wrote:
> The logic there which adds a dependency note to Sphinx cache
> is not taking into account that the build dir may not be
> the source dir. This causes a performance regression:
> 
> $ time make O=/tmp/foo SPHINXDIRS=admin-guide htmldocs
> 
> 	[OUTDATED]
> 	Added: set()
> 	Changed: {'abi-obsolete', 'abi-removed', 'abi-stable-files', 'abi-obsolete-files', 'abi-stable', 'abi', 'abi-removed-files', 'abi-testing-files', 'abi-testing', 'gpio/index', 'gpio/obsolete'}
> 	Removed: set()
> 	All docs count: 385
> 	Found docs count: 385
> 
> 	real    0m11,324s
> 	user    0m15,783s
> 	sys     0m1,164s
> 
> To get the root cause of the problem (ABI files reported as changed),
> I used this changeset:
> 
> 	diff --git a/Documentation/conf.py b/Documentation/conf.py
> 	index e8766e689c1b..ab486623bd8b 100644
> 	--- a/Documentation/conf.py
> 	+++ b/Documentation/conf.py
> 	@@ -571,3 +571,16 @@ def setup(app):
> 	     """Patterns need to be updated at init time on older Sphinx versions"""
> 
> 	     app.connect('config-inited', update_patterns)
> 	+    app.connect('env-get-outdated', on_outdated)
> 	+
> 	+def on_outdated(app, env, added, changed, removed):
> 	+    """Track cache outdated due to added/changed/removed files"""
> 	+    print("\n[OUTDATED]")
> 	+    print(f"Added: {added}")
> 	+    print(f"Changed: {changed}")
> 	+    print(f"Removed: {removed}")
> 	+    print(f"All docs count: {len(env.all_docs)}")
> 	+    print(f"Found docs count: {len(env.found_docs)}")
> 	+
> 	+    # Just return what we have
> 	+    return added | changed | removed
> 
> Reported-by: Akira Yokosawa <akiyks@gmail.com>
> Closes: https://lore.kernel.org/linux-doc/c174f7c5-ec21-4eae-b1c3-f643cca90d9d@gmail.com/
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Tested-by: Akira Yokosawa <akiyks@gmail.com>

Thanks!

> ---
> v2: updated description. No changes at the diff itself
> 
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