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Speedup Ninja backend with many extract_objects or targets #13879

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Speedup Ninja backend with many extract_objects or targets #13879

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bonzini
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@bonzini bonzini commented Nov 6, 2024 •
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This speeds up the target generation of QEMU, which is very slow.

  • Before: 41 seconds (total time 174 seconds)
  • After: 29 21 seconds (total time 150 134 seconds)

@bonzini bonzini force-pushed the speedups branch 4 times, most recently from c7bd527 to f501fa9 Compare November 6, 2024 16:08
eli-schwartz
eli-schwartz requested changes Nov 6, 2024
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mesonbuild/backend/backends.py Outdated
Comment on lines 479 to 486
proj_dir_to_build_root: str) -> T.Tuple[T.List[str], T.List[build.BuildTargetTypes]]:
obj_list: T.List[str] = []
deps: T.List[build.BuildTargetTypes] = []
proj_dir_to_build_root: str,
obj_list: T.List[str], deps: T.List[build.BuildTargetTypes]) -> None:
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@dcbaker I suspect you may have some opinions about this.

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--verbose? :)

mesonbuild/compilers/compilers.py Outdated Show resolved Hide resolved
@bonzini bonzini force-pushed the speedups branch 4 times, most recently from 47d8542 to 8c0faca Compare November 7, 2024 09:35
@bonzini bonzini changed the title Speedup Ninja backend with many extract_objects Speedup Ninja backend with many extract_objects or targets Nov 7, 2024
@bonzini bonzini force-pushed the speedups branch 2 times, most recently from 234adf6 to bc660cb Compare November 7, 2024 12:13
@bonzini bonzini requested a review from eli-schwartz November 7, 2024 12:15
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Pushed 1b15bd0 and 58d1efb for now. The backend changes look very interesting, though also take quite a bit more effort to understand what the code is doing both before and after. :D

@bonzini bonzini force-pushed the speedups branch 3 times, most recently from 14150bd to 84b08ff Compare November 20, 2024 07:16
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bonzini commented Nov 20, 2024

The backend changes look very interesting, though also take quite a bit more effort to understand what the code is doing both before and after. :D

Fair enough! I've split the changes more finely, which should be easier to both review and apply individually. If you prefer to have multiple PRs let me know.

@bonzini bonzini force-pushed the speedups branch 2 times, most recently from 60192f2 to 58a072d Compare November 20, 2024 07:22
@bonzini bonzini requested a review from eli-schwartz November 20, 2024 13:46
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bonzini commented Dec 5, 2024

Ping. :)

@bonzini
compilers: cache the results of is_source()
a2346a4 
is_source() is called almost 900000 times in a QEMU setup.  Together with
the previously added caching, this basically removes _determine_ext_objs()
from the profile when building QEMU.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
@bonzini
utils: cache build directory files
833de01 
get_target_generated_sources often calls File.from_built_relative on
the same file, if it is used by many sources.  This is a somewhat
expensive call both CPU- and memory-wise, so cache the creation
of build-directory files as well.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
@bonzini
ninjabackend: use File.from_built_relative()
ac4eec5 
Do not reinvent it in NinjaBackend.determine_ext_objs(), so as to use
the recently added caching of the results of File.from_built_relative().

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
@bonzini
ninjabackend: prefer "in" to regex search
bb23db4 
Regexes can be surprisingly slow.  This small change brings
ninja_quote() from 12 to 3 seconds when building QEMU.
Before:

   ncalls  tottime  percall  cumtime  percall
  3734443    4.872    0.000   11.944    0.000

After:

   ncalls  tottime  percall  cumtime  percall
  3595590    3.193    0.000    3.196    0.000

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
@bonzini
arglist: optimize __init__()
5038f5d 
"Inline" CompilerArgs.__iter__() into CompilerArgs.__init__(), so that
replace list(Iterable) is replaced by the much faster list(List).

Before:

   ncalls  tottime  cumtime
    19268    0.163    3.586 arglist.py:97(__init__)

After:

   ncalls  tottime  cumtime
    18674    0.211    3.442 arglist.py:97(__init__)

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
@bonzini
arglist: optimize flush_pre_post(), and __iadd__() with it
ea2bfed 
Unless an argument is marked as Dedup.OVERRIDDEN, pre_flush_set and
post_flush_set will always be empty and the loops in flush_pre_post()
will not be doing anything interesting:

        for a in self.pre:
            dedup = self._can_dedup(a)
            if a not in pre_flush_set:
                # This just makes new a copy of self.pre
                new.append(a)
                if dedup is Dedup.OVERRIDDEN:
                    # this never happens
                    pre_flush_set.add(a)

        for a in reversed(self.post):
            dedup = self._can_dedup(a)
            if a not in post_flush_set:
                # Here self.post is reversed twice
                post_flush.appendleft(a)
                if dedup is Dedup.OVERRIDDEN:
                    # this never happens
                    post_flush_set.add(a)
        new.extend(post_flush)

In this case it's possible to avoid expensive calls and loops, instead
relying as much on Python builtins as possible.  Track whether any options
have that flag and if not just concatenate pre, _container and post.

Before:

   ncalls  tottime  cumtime
    45127    0.251    4.530 arglist.py:142(__iter__)
    81866    3.623    5.013 arglist.py:108(flush_pre_post)
    76618    3.793    5.338 arglist.py:273(__iadd__)

After:

    35647    0.156    0.627 arglist.py:160(__iter__)
    78998    2.627    3.603 arglist.py:116(flush_pre_post)
    73774    3.605    5.049 arglist.py:292(__iadd__)

The time in __iadd__ is reduced because it calls __iter__, which flushes
pre and post.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
@bonzini
arglist: post is only appended to, make it a list
ea18868 
self.post is only ever appended to on the right hand.  However,
it is then reversed twice in flush_pre_post(), by using "for a in
reversed.post()" and appendleft() within the loop.  It would be tempting
to use appendleft() in __iadd__ to avoid the call to reversed(), but that
is not a good idea because the loop of flush_pre_post() is part of a slow
path.  It's rather more important to use a fast extend-with-list-argument
in the fast path where needs_override_check if False.

For clarity, and to remove the temptation, make "post" a list instead
of a deque.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
@bonzini
backends: avoid extend() in _flatten_object_list
4223bf6 
Accumulate into lists that are passed by the caller, thus avoiding
allocations and calls to extend() on recursive extract_objects().

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
@bonzini
backends: remove unused argument
4eeb53b 
The proj_dir_to_build_root argument of determine_ext_objs() is always empty,
remove it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
@bonzini
backends: avoid os.path.join in common case of _flatten_object_list
647c8bb 
proj_dir_to_build_root is empty by default, in fact always except on
some cases of the VS2010 backend.

Add it after the fact in flatten_object_list(), which reduces the
numbers of os.path.join().

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@jpakkane jpakkane Awaiting requested review from jpakkane jpakkane is a code owner

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@bonzini @eli-schwartz