Profiling revealed that we were spending lots of time growing the buffer.
Buffer operations is definitely something we want to optimize, but for
this specific benchmark what we're interested in is UTF-8 scanning performance.
Each iteration of the two scaning benchmark were producing 20MB of JSON,
now they only produce 5MB.
Now:
```
== Encoding mostly utf8 (5001001 bytes)
ruby 3.4.0dev (2024-10-18T19:01:45Z master https://github.com/ruby/json/commit/7be9a333ca) +YJIT +PRISM [arm64-darwin23]
Warming up --------------------------------------
json 35.000 i/100ms
oj 36.000 i/100ms
rapidjson 10.000 i/100ms
Calculating -------------------------------------
json 359.161 (± 1.4%) i/s (2.78 ms/i) - 1.820k in 5.068542s
oj 359.699 (± 0.6%) i/s (2.78 ms/i) - 1.800k in 5.004291s
rapidjson 99.687 (± 2.0%) i/s (10.03 ms/i) - 500.000 in 5.017321s
Comparison:
json: 359.2 i/s
oj: 359.7 i/s - same-ish: difference falls within error
rapidjson: 99.7 i/s - 3.60x slower
```
https://github.com/ruby/json/commit/1a338532d2
Now that we've inlined the eden_heap into the size_pool, we should
rename the size_pool to heap. So that Ruby contains multiple heaps, with
different sized objects.
The term heap as a collection of memory pages is more in memory
management nomenclature, whereas size_pool was a name chosen out of
necessity during the development of the Variable Width Allocation
features of Ruby.
The concept of size pools was introduced in order to facilitate
different sized objects (other than the default 40 bytes). They wrapped
the eden heap and the tomb heap, and some related state, and provided a
reasonably simple way of duplicating all related concerns, to provide
multiple pools that all shared the same structure but held different
objects.
Since then various changes have happend in Ruby's memory layout:
* The concept of tomb heaps has been replaced by a global free pages list,
with each page having it's slot size reconfigured at the point when it
is resurrected
* the eden heap has been inlined into the size pool itself, so that now
the size pool directly controls the free_pages list, the sweeping
page, the compaction cursor and the other state that was previously
being managed by the eden heap.
Now that there is no need for a heap wrapper, we should refer to the
collection of pages containing Ruby objects as a heap again rather than
a size pool
With embedded strings we often have some space left in the slot, which
we can use to store the string Hash code.
It's probably only worth it for string literals, as they are the ones
likely to be used as hash keys.
We chose to store the Hash code right after the string terminator as to
make it easy/fast to compute, and not require one more union in RString.
```
compare-ruby: ruby 3.4.0dev (2024-04-22T06:32:21Z main f77618c1fa) [arm64-darwin23]
built-ruby: ruby 3.4.0dev (2024-04-22T10:13:03Z interned-string-ha.. 8a1a32331b) [arm64-darwin23]
last_commit=Precompute embedded string literals hash code
| |compare-ruby|built-ruby|
|:-----------|-----------:|---------:|
|symbol | 39.275M| 39.753M|
| | -| 1.01x|
|dyn_symbol | 37.348M| 37.704M|
| | -| 1.01x|
|small_lit | 29.514M| 33.948M|
| | -| 1.15x|
|frozen_lit | 27.180M| 33.056M|
| | -| 1.22x|
|iseq_lit | 27.391M| 32.242M|
| | -| 1.18x|
```
Co-Authored-By: Étienne Barrié <etienne.barrie@gmail.com>
These show gains from the recent optimization commits:
```
arg_splat
miniruby: 7346039.9 i/s
miniruby-before: 4692240.8 i/s - 1.57x slower
arg_splat_block
miniruby: 6539749.6 i/s
miniruby-before: 4358063.6 i/s - 1.50x slower
splat_kw_splat
miniruby: 5433641.5 i/s
miniruby-before: 3851048.6 i/s - 1.41x slower
splat_kw_splat_block
miniruby: 4916137.1 i/s
miniruby-before: 3477090.1 i/s - 1.41x slower
splat_kw_block
miniruby: 2912829.5 i/s
miniruby-before: 2465611.7 i/s - 1.18x slower
arg_splat_post
miniruby: 2195208.2 i/s
miniruby-before: 1860204.3 i/s - 1.18x slower
```
zsuper only speeds up in the post argument case, because
it was already set to use splatarray false in cases where
there were no post arguments.
Thanks to the new semantics from [ruby-core:115808], `**nil` is now
equivalent to `**{}`. Since the only thing one could do with anonymous
keyword rest parameter is to delegate it with `**`, nil is just as good
as an empty hash. Using nil avoids allocating an empty hash.
This is particularly important for `...` methods since they now use
`**kwrest` under the hood after 4f77d8d328. Most calls don't pass
keywords.
Comparison:
fw_no_kw
post: 9816800.9 i/s
pre: 8570297.0 i/s - 1.15x slower
The following code previously caused a crash:
```ruby
h = {}
1000000.times{|i| h[i.to_s.to_sym] = i}
def f(kw: 1, **kws) end
f(**h)
```
Inside a thread or fiber, the size of the keyword splat could be much smaller
and still cause a crash.
I found this issue while optimizing method calling by reducing implicit
allocations. Given the following code:
```ruby
def f(kw: , **kws) end
kw = {kw: 1}
f(**kw)
```
The `f(**kw)` call previously allocated two hashes callee side instead of a
single hash. This is because `setup_parameters_complex` would extract the
keywords from the keyword splat hash to the C stack, to attempt to mirror
the case when literal keywords are passed without a keyword splat. Then,
`make_rest_kw_hash` would build a new hash based on the extracted keywords
that weren't used for literal keywords.
Switch the implementation so that if a keyword splat is passed, literal keywords
are deleted from the keyword splat hash (or a copy of the hash if the hash is
not mutable).
In addition to avoiding the crash, this new approach is much more
efficient in all cases. With the included benchmark:
```
1
miniruby: 5247879.9 i/s
miniruby-before: 2474050.2 i/s - 2.12x slower
1_mutable
miniruby: 1797036.5 i/s
miniruby-before: 1239543.3 i/s - 1.45x slower
10
miniruby: 1094750.1 i/s
miniruby-before: 365529.6 i/s - 2.99x slower
10_mutable
miniruby: 407781.7 i/s
miniruby-before: 225364.0 i/s - 1.81x slower
100
miniruby: 100992.3 i/s
miniruby-before: 32703.6 i/s - 3.09x slower
100_mutable
miniruby: 40092.3 i/s
miniruby-before: 21266.9 i/s - 1.89x slower
1000
miniruby: 21694.2 i/s
miniruby-before: 4949.8 i/s - 4.38x slower
1000_mutable
miniruby: 5819.5 i/s
miniruby-before: 2995.0 i/s - 1.94x slower
```
To avoid stack overflow, Ruby splits compilation of large arrays
into smaller arrays, and concatenates the small arrays together.
It previously used newarray/concatarray for this, which is
inefficient. This switches the compilation to use pushtoarray,
which is much faster. This makes almost all literal arrays only
allocate a single array.
For cases where there is a large amount of static values in the
array, Ruby will statically compile subarrays, and previously
added them using concatarray. This switches to concattoarray,
avoiding an array allocation for the append.
Keyword splats are also supported in arrays, and ignored if the
keyword splat is empty. Previously, this used newarraykwsplat and
concatarray. This still uses newarraykwsplat, but switches to
concattoarray to save an allocation. So large arrays with keyword
splats can allocate 2 arrays instead of 1.
Previously, for the following array sizes (assuming local variable
access for each element), Ruby allocated the following number of
arrays:
1000 elements: 7 arrays
10000 elements: 79 arrays
100000 elements: 781 arrays
With these changes, only a single array is allocated (or 2 for a
large array with a keyword splat.
Results using the included benchmark:
```
array_1000
miniruby: 34770.0 i/s
./miniruby-before: 10511.7 i/s - 3.31x slower
array_10000
miniruby: 4938.8 i/s
./miniruby-before: 483.8 i/s - 10.21x slower
array_100000
miniruby: 727.2 i/s
./miniruby-before: 4.1 i/s - 176.98x slower
```
Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>
This follows the same approach used for attr_reader/attr_writer in
2d98593bf5, skipping the checking for
tracing after the first call using the call cache, and clearing the
call cache when tracing is turned on/off.
Fixes [Bug #18886]
`String#+@` is 2-3 times faster than `String#dup` because it can
directly go through `rb_str_dup` instead of using the generic
much slower `rb_obj_dup`.
This fact led to the existance of the ugly `Performance/UnfreezeString`
rubocop performance rule that encourage users to rewrite the much
more readable and convenient `"foo".dup` into the ugly `(+"foo")`.
Let's make that rubocop rule useless.
```
compare-ruby: ruby 3.3.0dev (2023-11-20T02:02:55Z master 701b0650de) [arm64-darwin22]
last_commit=[ruby/prism] feat: add encoding for IBM865 (https://github.com/ruby/prism/pull/1884)
built-ruby: ruby 3.3.0dev (2023-11-20T12:51:45Z faster-str-lit-dup 6b745bbc5d) [arm64-darwin22]
warming up..
| |compare-ruby|built-ruby|
|:------|-----------:|---------:|
|uplus | 16.312M| 16.332M|
| | -| 1.00x|
|dup | 5.912M| 16.329M|
| | -| 2.76x|
```
When an inline cache misses, it is very likely that the stale shape_id
and the current instance shape_id have a close common ancestor.
For example if the instance variable is sometimes frozen sometimes
not, one of the two shape will be the direct parent of the other.
Another pattern that commonly cause IC misses is "memoization",
in such case the object will have a "base common shape" and then
a number of close descendants.
In addition, when we find a common ancestor, we store it in the
inline cache instead of the current shape. This help prevent the
cache from flip-flopping, ensuring the next lookup will be marginally
faster and more generally avoid writing in memory too much.
However, now that shapes have an ancestors index, we only check
for a few ancestors before falling back to use the index.
So overall this change speeds up what is assumed to be the more common
case, but makes what is assumed to be the less common case a bit slower.
```
compare-ruby: ruby 3.3.0dev (2023-10-26T05:30:17Z master 701ca070b4) [arm64-darwin22]
built-ruby: ruby 3.3.0dev (2023-10-26T09:25:09Z shapes_double_sear.. a723a85235) [arm64-darwin22]
warming up......
| |compare-ruby|built-ruby|
|:------------------------------------|-----------:|---------:|
|vm_ivar_stable_shape | 11.672M| 11.679M|
| | -| 1.00x|
|vm_ivar_memoize_unstable_shape | 7.551M| 10.506M|
| | -| 1.39x|
|vm_ivar_memoize_unstable_shape_miss | 11.591M| 11.624M|
| | -| 1.00x|
|vm_ivar_unstable_undef | 9.037M| 7.981M|
| | 1.13x| -|
|vm_ivar_divergent_shape | 8.034M| 6.657M|
| | 1.21x| -|
|vm_ivar_divergent_shape_imbalanced | 10.471M| 9.231M|
| | 1.13x| -|
```
Co-Authored-By: John Hawthorn <john@hawthorn.email>
This is an experimental commit that uses a functional red-black tree to
create an index of the ancestor shapes. It uses an Okasaki style
functional red black tree:
https://www.cs.tufts.edu/comp/150FP/archive/chris-okasaki/redblack99.pdf
This tree is advantageous because:
* It offers O(n log n) insertions and O(n log n) lookups.
* It shares memory with previous "versions" of the tree
When we insert a node in the tree, only the parts of the tree that need
to be rebalanced are newly allocated. Parts of the tree that don't need
to be rebalanced are not reallocated, so "new trees" are able to share
memory with old trees. This is in contrast to a sorted set where we
would have to duplicate the set, and also resort the set on each
insertion.
I've added a new stat to RubyVM.stat so we can understand how the red
black tree increases.
On Range#bsearch for endless ranges, we try positions at `begin + 2**i` (i = 0, 1, 2, ...)
to find a point that satisfies a given condition.
Subsequently, we perform binary searching with the interval `[begin, begin + 2**n]`.
However, the interval `[begin + 2**(n-1), begin + 2**n]` is sufficient for binary search
because `begin + 2**(n-1)` does not satisfy the condition.
The same applies to beginless ranges.
Leave callers to convert byte index to char index, as well as
`rb_str_index`, so that `rb_str_rpartition` does not need to
re-convert char index to byte index.
In most of case `sort_by` works on primitive type.
Using `qsort_r` with function pointer is much slower than compare data directly.
I implement an intro sort which compare primitive data directly for `sort_by`.
We can even afford an O(n) type check before primitive data sort.
It still go faster.
CALLER_ARG_SPLAT is not necessary for method_missing. We just need
to unshift the method name into the arguments.
This optimizes all method_missing calls:
* mm(recv) ~9%
* mm(recv, *args) ~215% for args.length == 200
* mm(recv, *args, **kw) ~55% for args.length == 200
* mm(recv, **kw) ~22%
* mm(recv, kw: 1) ~100%
Note that empty argument splats do get slower with this approach,
by about 30-40%. Other than non-empty argument splats, other
argument splats are faster, with the speedup depending on the
number of arguments.
Similar to the bmethod/send optimization, this avoids using
CALLER_ARG_SPLAT if not necessary. As long as the receiver argument
can be shifted off, other arguments are passed through as-is.
This optimizes the following types of calls:
* symproc.(recv) ~5%
* symproc.(recv, *args) ~65% for args.length == 200
* symproc.(recv, *args, **kw) ~45% for args.length == 200
* symproc.(recv, **kw) ~30%
* symproc.(recv, kw: 1) ~100%
Note that empty argument splats do get slower with this approach,
by about 2-3%. This is probably because iseq argument setup is
slower for empty argument splats than CALLER_SETUP_ARG is. Other
than non-empty argument splats, other argument splats are faster,
with the speedup depending on the number of arguments.
The following types of calls are not optimized:
* symproc.(*args)
* symproc.(*args, **kw)
This is because the you cannot shift the receiver argument off
without first splatting the arg.
Similar to the bmethod optimization, this avoids using
CALLER_ARG_SPLAT if not necessary. As long as the method argument
can be shifted off, other arguments are passed through as-is.
This optimizes the following types of calls:
* send(meth, arg) ~5%
* send(meth, *args) ~75% for args.length == 200
* send(meth, *args, **kw) ~50% for args.length == 200
* send(meth, **kw) ~25%
* send(meth, kw: 1) ~115%
Note that empty argument splats do get slower with this approach,
by about 20%. This is probably because iseq argument setup is
slower for empty argument splats than CALLER_SETUP_ARG is. Other
than non-empty argument splats, other argument splats are faster,
with the speedup depending on the number of arguments.
The following types of calls are not optimized:
* send(*args)
* send(*args, **kw)
This is because the you cannot shift the method argument off
without first splatting the arg.
This optimizes the following calls:
* ~10-15% for f(*a) when a does not end with a flagged keywords hash
* ~10-15% for f(*a) when a ends with an empty flagged keywords hash
* ~35-40% for f(*a, **kw) if kw is empty
This still copies the array contents to the VM stack, but avoids some
overhead. It would be faster to use the array pointer directly,
but that could cause problems if the array was modified during
the call to the function. You could do that optimization for frozen
arrays, but as splatting frozen arrays is uncommon, and the speedup
is minimal (<5%), it doesn't seem worth it.
The vm_send_cfunc benchmark has been updated to test additional cfunc
call types, and the numbers above were taken from the benchmark results.
Jean Boussier
Hiroshi SHIBATA
ydah
Matt Valentine-House
Nobuyoshi Nakada
aoki1980taichi
Jean Boussier
Aaron Patterson
Takashi Kokubun
Jeremy Evans
Alan Wu
Aaron Patterson
Kouhei Yanagita
nekoyama32767