mimalloc
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Potential Performance Regression with `dev3`
I just did a very quick tests with multithreaded allocation and deallocation. In this the dev3 branch does not perform very well. My CPU is 13th Gen Intel(R) Core(TM) i7-13850HX. The test code is in Rust, I hope this is ok:
# Cargo.toml
[package]
name = "experiment"
edition = "2021"
[dependencies]
rand = "0.9.1"
// main.rs
use rand::{rngs::ThreadRng, Rng};
use std::{hint::black_box, thread, time::Instant};
fn main() {
let start = Instant::now();
thread::scope(|scope| {
for _ in 0..100 {
scope.spawn(|| {
let mut rnd = ThreadRng::default();
for _ in 0..1000000 {
let allocation = vec![0u8; rnd.random_range(1..1000)];
black_box(&allocation);
if rnd.random_bool(0.24) {
allocation.leak();
}
}
});
}
});
let duration = start.elapsed();
println!("took {}", duration.as_secs_f32());
}
My results are (built in --release mode):
❯ LD_PRELOAD=/usr/lib/libjemalloc.so.2 ./experiment
took 0.6000622
❯ LD_PRELOAD=/home/abc/temp/mimalloc/build/libmimalloc.so.1.9 ./experiment
took 0.63197255
❯ LD_PRELOAD=/home/abc/temp/mimalloc/build/libmimalloc.so.2.2 ./experiment
took 0.62372595
❯ LD_PRELOAD=/home/abc/temp/mimalloc/build/libmimalloc.so.3.1 ./experiment
took 4.9627113
Thanks -- something strange is going on as v3 should not be that much slower. What platform are you using? Is this v3.1.5 ? I rewrote the test in C++ to make sure the malloc/free calls are explicit; when I run this on macOS there is no difference in execution time between mimalloc v2 and v3. So, it may be a Linux specific thing, or perhaps something with Rust that causes the strange slowdown. Can you check if my C++ reflects your test accurately? I added the summing to make sure the allocation etc does not get optimized away:
static std::atomic<long> gsum;
static void local_alloc() {
long sum = 0;
for(int i = 0; i < 1000000; i++) {
const int n = 1 + std::rand() % 1000;
uint8_t* p = (uint8_t*)calloc(n, 1);
p[0] = 1;
sum += p[std::rand() % n];
if ((std::rand() % 100) > 24) {
free(p);
}
}
gsum += sum;
}
static void test_thread_leak() {
std::vector<std::thread> threads;
for (int i=1; i<=100; ++i) {
threads.emplace_back(std::thread(&local_alloc));
}
for (auto& th : threads) {
th.join();
}
}
ps. Maybe run the v3 test with MIMALLOC_VERBOSE=1 to see if it was compiled with debug info on or something?
What platform are you using?
Arch Linux with Kernel 6.15: Linux ... 6.15.2-arch1-1 #1 SMP PREEMPT_DYNAMIC Tue, 10 Jun 2025 21:32:33 +0000 x86_64 GNU/Linux
Is this v3.1.5 ?
mimalloc: v3.1.6, release, git v3.1.5-1-gdc84ea78 (built on Jun 17 2025, 09:39:45)
Can you check if my C++ reflects your test accurately?
The Code seems fine to me, but it behaves wildly differently. Your Code takes 60s with mimalloc v2 while my Rust Code takes 0.6s with mimalloc v2. I am using clang 20 vs Rust nightly, which should basically be the same optimizations. I even replicated the summing in my Rust code, no difference.
So either this is some aggressive opimizations, that only trigger in the Rust code for some reason or it has something to do with the random number generation.
Either way, there is an issue with the mimalloc using the Rust binary, independent of how much work actually happens there and how much got somehow optimized away. I am just not sure how to dig into it further.
Rust Binary with Mimalloc 2.2
mimalloc: v2.2.5, release, git v2.2.4-37-g09a27098 (built on Jun 17 2025, 09:38:16)
mimalloc: option 'show_errors': 0
mimalloc: option 'show_stats': 0
mimalloc: option 'verbose': 1
mimalloc: option 'eager_commit': 1
mimalloc: option 'arena_eager_commit': 2
mimalloc: option 'purge_decommits': 1
mimalloc: option 'allow_large_os_pages': 2
mimalloc: option 'reserve_huge_os_pages': 0
mimalloc: option 'reserve_huge_os_pages_at': -1
mimalloc: option 'reserve_os_memory': 0 KiB
mimalloc: option 'deprecated_segment_cache': 0
mimalloc: option 'deprecated_page_reset': 0
mimalloc: option 'abandoned_page_purge': 0
mimalloc: option 'deprecated_segment_reset': 0
mimalloc: option 'eager_commit_delay': 1
mimalloc: option 'purge_delay': 10
mimalloc: option 'use_numa_nodes': 0
mimalloc: option 'disallow_os_alloc': 0
mimalloc: option 'os_tag': 100
mimalloc: option 'max_errors': 32
mimalloc: option 'max_warnings': 32
mimalloc: option 'max_segment_reclaim': 10
mimalloc: option 'destroy_on_exit': 0
mimalloc: option 'arena_reserve': 1048576 KiB
mimalloc: option 'arena_purge_mult': 10
mimalloc: option 'purge_extend_delay': 1
mimalloc: option 'abandoned_reclaim_on_free': 0
mimalloc: option 'disallow_arena_alloc': 0
mimalloc: option 'retry_on_oom': 400
mimalloc: option 'visit_abandoned': 0
mimalloc: option 'guarded_min': 0
mimalloc: option 'guarded_max': 1073741824
mimalloc: option 'guarded_precise': 0
mimalloc: option 'guarded_sample_rate': 0
mimalloc: option 'guarded_sample_seed': 0
mimalloc: option 'target_segments_per_thread': 0
mimalloc: option 'generic_collect': 10000
mimalloc: debug level : 0
mimalloc: secure level: 0
mimalloc: mem tracking: none
mimalloc: process init: 0x7FBAF2FC6F80
mimalloc: using 1 numa regions
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: warning: thread 0x7FBAEC47D6C0: unable to allocate aligned OS memory directly, fall back to over-allocation (size: 0x80000000 bytes, address: 0x7FBA66600000, alignment: 0x2000000, commit: 1)
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
took 0.6289115
heap stats: peak total current block total#
reserved: 56.0 GiB 58.0 GiB 56.0 GiB
committed: 55.9 GiB 58.0 GiB 55.8 GiB
reset: 0
purged: 134.6 MiB
touched: 32.5 MiB 33.0 MiB 31.7 MiB
segments: 1.0 Ki 1.1 Ki 139 not all freed
-abandoned: 926 926 262 not all freed
-cached: 0 0 0 ok
pages: 0 0 -336 not all freed
-abandoned: 456.8 Ki 456.8 Ki 127.8 Ki not all freed
-extended: 0
-retire: 0
arenas: 32
-rollback: 0
mmaps: 148
commits: 0
resets: 0
purges: 19
guarded: 0
threads: 99 100 0 ok
searches: 0.0 avg
numa nodes: 1
elapsed: 0.629 s
process: user: 10.722 s, system: 5.310 s, faults: 0, rss: 12.3 GiB, commit: 55.9 GiB
mimalloc: process done: 0x7FBAF2FC6F80
Rust Binary with Mimalloc 3.1
mimalloc: v3.1.6, release, git v3.1.5-1-gdc84ea78 (built on Jun 17 2025, 09:39:45)
mimalloc: option 'show_errors': 0
mimalloc: option 'show_stats': 0
mimalloc: option 'verbose': 1
mimalloc: option 'eager_commit': 1
mimalloc: option 'arena_eager_commit': 2
mimalloc: option 'purge_decommits': 1
mimalloc: option 'allow_large_os_pages': 2
mimalloc: option 'reserve_huge_os_pages': 0
mimalloc: option 'reserve_huge_os_pages_at': -1
mimalloc: option 'reserve_os_memory': 0 KiB
mimalloc: option 'deprecated_segment_cache': 0
mimalloc: option 'deprecated_page_reset': 0
mimalloc: option 'abandoned_page_purge': 0
mimalloc: option 'deprecated_segment_reset': 0
mimalloc: option 'eager_commit_delay': 1
mimalloc: option 'purge_delay': 1000
mimalloc: option 'use_numa_nodes': 0
mimalloc: option 'disallow_os_alloc': 0
mimalloc: option 'os_tag': 100
mimalloc: option 'max_errors': 32
mimalloc: option 'max_warnings': 32
mimalloc: option 'deprecated_max_segment_reclaim': 10
mimalloc: option 'destroy_on_exit': 0
mimalloc: option 'arena_reserve': 1048576 KiB
mimalloc: option 'arena_purge_mult': 1
mimalloc: option 'deprecated_purge_extend_delay': 1
mimalloc: option 'disallow_arena_alloc': 0
mimalloc: option 'retry_on_oom': 400
mimalloc: option 'visit_abandoned': 0
mimalloc: option 'guarded_min': 0
mimalloc: option 'guarded_max': 1073741824
mimalloc: option 'guarded_precise': 0
mimalloc: option 'guarded_sample_rate': 0
mimalloc: option 'guarded_sample_seed': 0
mimalloc: option 'generic_collect': 10000
mimalloc: option 'page_reclaim_on_free': 0
mimalloc: option 'page_full_retain': 2
mimalloc: option 'page_max_candidates': 4
mimalloc: option 'max_vabits': 0
mimalloc: option 'pagemap_commit': 0
mimalloc: option 'page_commit_on_demand': 0
mimalloc: option 'page_max_reclaim': -1
mimalloc: option 'page_cross_thread_max_reclaim': 32
mimalloc: debug level : 0
mimalloc: secure level: 0
mimalloc: mem tracking: none
mimalloc: process init: 0x7F8A2166AF80
mimalloc: reserved 1048576 KiB memory
mimalloc: using 1 numa regions
mimalloc: using 1 numa regions
mimalloc: using 1 numa regions
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 4194304 KiB memory
took 4.6002703
heap stats: peak total current block total#
reserved: 16.0 GiB 16.0 GiB 16.0 GiB
committed: 12.2 GiB 12.2 GiB 12.2 GiB
reset: 0
purged: 0
touched: 0 0 0 ok
pages: 196.6 Ki 807.8 Ki 196.3 Ki not all freed
-abandoned: 196.6 Ki 755.2 Ki 196.3 Ki not all freed
-reclaima: 1.8 Ki
-reclaimf: 557.0 Ki
-reabandon: 0
-waits: 0
-extended: 0
-retire: 0
arenas: 9
-rollback: 0
mmaps: 658
commits: 0
resets: 0
purges: 0
guarded: 0
threads: 100 100 0 ok
searches: 1.0 avg
numa nodes: 1
elapsed: 4.601 s
process: user: 19.448 s, system: 103.406 s, faults: 0, rss: 12.2 GiB, commit: 12.2 GiB
mimalloc: process done: 0x7F8A2166AF80
C++ Binary with Mimalloc 2.2
mimalloc: process init: 0x7FD4CE100780
mimalloc: using 1 numa regions
mimalloc: v2.2.5, release, git v2.2.4-37-g09a27098 (built on Jun 17 2025, 09:38:16)
mimalloc: option 'show_errors': 0
mimalloc: option 'show_stats': 0
mimalloc: option 'verbose': 1
mimalloc: option 'eager_commit': 1
mimalloc: option 'arena_eager_commit': 2
mimalloc: option 'purge_decommits': 1
mimalloc: option 'allow_large_os_pages': 2
mimalloc: option 'reserve_huge_os_pages': 0
mimalloc: option 'reserve_huge_os_pages_at': -1
mimalloc: option 'reserve_os_memory': 0 KiB
mimalloc: option 'deprecated_segment_cache': 0
mimalloc: option 'deprecated_page_reset': 0
mimalloc: option 'abandoned_page_purge': 0
mimalloc: option 'deprecated_segment_reset': 0
mimalloc: option 'eager_commit_delay': 1
mimalloc: option 'purge_delay': 10
mimalloc: option 'use_numa_nodes': 0
mimalloc: option 'disallow_os_alloc': 0
mimalloc: option 'os_tag': 100
mimalloc: option 'max_errors': 32
mimalloc: option 'max_warnings': 32
mimalloc: option 'max_segment_reclaim': 10
mimalloc: option 'destroy_on_exit': 0
mimalloc: option 'arena_reserve': 1048576 KiB
mimalloc: option 'arena_purge_mult': 10
mimalloc: option 'purge_extend_delay': 1
mimalloc: option 'abandoned_reclaim_on_free': 0
mimalloc: option 'disallow_arena_alloc': 0
mimalloc: option 'retry_on_oom': 400
mimalloc: option 'visit_abandoned': 0
mimalloc: option 'guarded_min': 0
mimalloc: option 'guarded_max': 1073741824
mimalloc: option 'guarded_precise': 0
mimalloc: option 'guarded_sample_rate': 0
mimalloc: option 'guarded_sample_seed': 0
mimalloc: option 'target_segments_per_thread': 0
mimalloc: option 'generic_collect': 10000
mimalloc: debug level : 0
mimalloc: secure level: 0
mimalloc: mem tracking: none
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: warning: thread 0x7FD4BB2F26C0: unable to allocate aligned OS memory directly, fall back to over-allocation (size: 0x80000000 bytes, address: 0x7FD41BA00000, alignment: 0x2000000, commit: 1)
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
heap stats: peak total current block total#
reserved: 16.0 GiB 18.0 GiB 16.0 GiB
committed: 15.7 GiB 18.0 GiB 14.8 GiB
reset: 0
purged: 1.1 GiB
touched: 31.1 MiB 31.2 MiB 30.1 MiB
segments: 680 715 1 not all freed
-abandoned: 678 679 464 not all freed
-cached: 0 0 0 ok
pages: 0 0 -292 not all freed
-abandoned: 297.3 Ki 297.4 Ki 205.4 Ki not all freed
-extended: 0
-retire: 0
arenas: 12
-rollback: 0
mmaps: 115
commits: 0
resets: 0
purges: 51
guarded: 0
threads: 100 100 0 ok
searches: 0.0 avg
numa nodes: 1
elapsed: 58.740 s
process: user: 92.683 s, system: 1532.769 s, faults: 0, rss: 12.8 GiB, commit: 15.7 GiB
mimalloc: process done: 0x7FD4CE100780
C++ Binary with Mimalloc 3.1
mimalloc: process init: 0x7FB3A7CCF780
mimalloc: warning: unable to allocate aligned OS memory directly, fall back to over-allocation (size: 0x20000 bytes, address: 0x7FB3A7E07000, alignment: 0x10000, commit: 1)
mimalloc: v3.1.6, release, git v3.1.5-1-gdc84ea78 (built on Jun 17 2025, 09:39:45)
mimalloc: option 'show_errors': 0
mimalloc: option 'show_stats': 0
mimalloc: option 'verbose': 1
mimalloc: option 'eager_commit': 1
mimalloc: option 'arena_eager_commit': 2
mimalloc: option 'purge_decommits': 1
mimalloc: option 'allow_large_os_pages': 2
mimalloc: option 'reserve_huge_os_pages': 0
mimalloc: option 'reserve_huge_os_pages_at': -1
mimalloc: option 'reserve_os_memory': 0 KiB
mimalloc: option 'deprecated_segment_cache': 0
mimalloc: option 'deprecated_page_reset': 0
mimalloc: option 'abandoned_page_purge': 0
mimalloc: option 'deprecated_segment_reset': 0
mimalloc: option 'eager_commit_delay': 1
mimalloc: option 'purge_delay': 1000
mimalloc: option 'use_numa_nodes': 0
mimalloc: option 'disallow_os_alloc': 0
mimalloc: option 'os_tag': 100
mimalloc: option 'max_errors': 32
mimalloc: option 'max_warnings': 32
mimalloc: option 'deprecated_max_segment_reclaim': 10
mimalloc: option 'destroy_on_exit': 0
mimalloc: option 'arena_reserve': 1048576 KiB
mimalloc: option 'arena_purge_mult': 1
mimalloc: option 'deprecated_purge_extend_delay': 1
mimalloc: option 'disallow_arena_alloc': 0
mimalloc: option 'retry_on_oom': 400
mimalloc: option 'visit_abandoned': 0
mimalloc: option 'guarded_min': 0
mimalloc: option 'guarded_max': 1073741824
mimalloc: option 'guarded_precise': 0
mimalloc: option 'guarded_sample_rate': 0
mimalloc: option 'guarded_sample_seed': 0
mimalloc: option 'generic_collect': 10000
mimalloc: option 'page_reclaim_on_free': 0
mimalloc: option 'page_full_retain': 2
mimalloc: option 'page_max_candidates': 4
mimalloc: option 'max_vabits': 0
mimalloc: option 'pagemap_commit': 0
mimalloc: option 'page_commit_on_demand': 0
mimalloc: option 'page_max_reclaim': -1
mimalloc: option 'page_cross_thread_max_reclaim': 32
mimalloc: debug level : 0
mimalloc: secure level: 0
mimalloc: mem tracking: none
mimalloc: reserved 1048576 KiB memory
mimalloc: using 1 numa regions
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 2097152 KiB memory
mimalloc: reserved 4194304 KiB memory
heap stats: peak total current block total#
reserved: 16.0 GiB 16.0 GiB 16.0 GiB
committed: 12.7 GiB 12.7 GiB 12.7 GiB
reset: 0
purged: 1.0 MiB
touched: 0 0 0 ok
pages: 205.1 Ki 805.4 Ki 204.8 Ki not all freed
-abandoned: 205.1 Ki 749.3 Ki 204.8 Ki not all freed
-reclaima: 1.1 Ki
-reclaimf: 543.3 Ki
-reabandon: 0
-waits: 0
-extended: 0
-retire: 0
arenas: 9
-rollback: 0
mmaps: 121
commits: 0
resets: 0
purges: 15
guarded: 0
threads: 100 100 0 ok
searches: 1.0 avg
numa nodes: 1
elapsed: 65.140 s
process: user: 105.080 s, system: 1692.281 s, faults: 0, rss: 12.7 GiB, commit: 12.7 GiB
mimalloc: process done: 0x7FB3A7CCF780
I am not sure how to interpret it correctly, but I noticed, that in the Rust binary, reserved/committed and mmaps have a big difference beween v2 and v3
I came across the same performance issues when upgrading from to v3, and I've been able to replicate similar results on both Linux (AMD Ryzen 3900x) and MacOS (ARM M1) using similar examples derived from the above. And then did some further digging... I don't have a smoking gun, but this might get us a bit closer. I hope this helps!
Setup
- AMD Ryzen 3900X running Linux under WSL
- Broadly similar results on M1 Macbook under OSX
- Broadly similar results on C++ side with both gcc and clang
I modified the benchmarks a bit to better reflect one of my own use cases where I noticed the performance regression in the first place. I also used a fast thread-local random number generator in C++, as the (shared?) rand() call used in the example above was responsible for the difference between Rust and C++ results. Now they're very close.
Note that I'm also using mi_zalloc_aligned in C++ because this is the function called from Rust when allocating a large zeroed vec. More on that below.
C++ (cpp-bench)
- mimalloc v2 took: 708 ms
- mimalloc v3 took: 8201 ms
Rust (rust-bench)
- mimalloc v2 took: 731 ms
- mimalloc v3 took: 8242 ms
Profiling
Using perf on the Rust build reveals ~50% of cycles spent in memset. Changing the call in C++ from mi_zalloc_aligned to mi_malloc_aligned reduces the runtime significantly in the mimalloc v3 case.
With V3:
- mi_zalloc_aligned: 8201 ms (as above - matches Rust use)
- mi_malloc_aligned: 427 ms
Although, of course, the results are then incorrect as we're expecting a zeroed allocation. But it does hint that the problem is related to zeroing out the allocated chunk in v3. We're doing the same thing in v2, but it's a lot faster.
Note that the same results as mi_zalloc_aligned are obtained if we use mi_malloc_aligned and then zero the allocated memory using memset. Similar results if I zero the array using AVX2 writes, so it's not as if the zeroing itself is slow either.
Given the above, it seems like this might be a cache coherence thing. If new allocations aren't as local as they were in v2 and often come from memory previously used by a different core, then perhaps what we're seeing here is the cost of that.
Run logs
cpp mimalloc v2
mimalloc: process init: 0x72EDFC8DE740
mimalloc: using 1 numa regions
mimalloc: v2.2.4, release (built on Dec 6 2025, 22:05:44)
mimalloc: option 'show_errors': 0
mimalloc: option 'show_stats': 1
mimalloc: option 'verbose': 1
mimalloc: option 'eager_commit': 1
mimalloc: option 'arena_eager_commit': 2
mimalloc: option 'purge_decommits': 1
mimalloc: option 'allow_large_os_pages': 2
mimalloc: option 'reserve_huge_os_pages': 0
mimalloc: option 'reserve_huge_os_pages_at': -1
mimalloc: option 'reserve_os_memory': 0 KiB
mimalloc: option 'deprecated_segment_cache': 0
mimalloc: option 'deprecated_page_reset': 0
mimalloc: option 'abandoned_page_purge': 0
mimalloc: option 'deprecated_segment_reset': 0
mimalloc: option 'eager_commit_delay': 1
mimalloc: option 'purge_delay': 10
mimalloc: option 'use_numa_nodes': 0
mimalloc: option 'disallow_os_alloc': 0
mimalloc: option 'os_tag': 100
mimalloc: option 'max_errors': 32
mimalloc: option 'max_warnings': 32
mimalloc: option 'max_segment_reclaim': 10
mimalloc: option 'destroy_on_exit': 0
mimalloc: option 'arena_reserve': 1048576 KiB
mimalloc: option 'arena_purge_mult': 10
mimalloc: option 'purge_extend_delay': 1
mimalloc: option 'abandoned_reclaim_on_free': 0
mimalloc: option 'disallow_arena_alloc': 0
mimalloc: option 'retry_on_oom': 400
mimalloc: option 'visit_abandoned': 0
mimalloc: option 'guarded_min': 0
mimalloc: option 'guarded_max': 1073741824
mimalloc: option 'guarded_precise': 0
mimalloc: option 'guarded_sample_rate': 0
mimalloc: option 'guarded_sample_seed': 0
mimalloc: option 'target_segments_per_thread': 0
mimalloc: option 'generic_collect': 10000
mimalloc: debug level : 0
mimalloc: secure level: 0
mimalloc: mem tracking: none
mimalloc: reserved 1048576 KiB memory
mimalloc: reserved 1048576 KiB memory
heap stats: peak total current block total#
reserved: 2.0 GiB 2.0 GiB 2.0 GiB
committed: 2.0 GiB 2.0 GiB 2.0 GiB
reset: 0
purged: 0
touched: 75.8 MiB 101.1 MiB -561.3 GiB
segments: 1.1 Ki 1.5 Ki 1 not all freed
-abandoned: 3 10 1 not all freed
-cached: 0 0 0 ok
pages: 0 0 -2.8 Mi not all freed
-abandoned: 3 10 1 not all freed
-extended: 0
-retire: 0
arenas: 2
-rollback: 0
mmaps: 28
commits: 0
resets: 0
purges: 0
guarded: 0
threads: 24 24 0 ok
searches: 0.0 avg
numa nodes: 1
elapsed: 0.698 s
process: user: 16.218 s, system: 0.051 s, faults: 0, rss: 23.8 MiB, commit: 2.0 GiB
mimalloc: process done: 0x72EDFC8DE740
........................
took: 697 ms
gsum: 3935
cpp mimalloc v3
mimalloc: process init: 0x74B7A70D5780
mimalloc: warning: unable to allocate aligned OS memory directly, fall back to over-allocation (size: 0x20000 bytes, address: 0x74B7A70B5000, alignment: 0x10000, commit: 1)
mimalloc: v3.1.5, release (built on Dec 6 2025, 22:09:34)
mimalloc: option 'show_errors': 0
mimalloc: option 'show_stats': 1
mimalloc: option 'verbose': 1
mimalloc: option 'eager_commit': 1
mimalloc: option 'arena_eager_commit': 2
mimalloc: option 'purge_decommits': 1
mimalloc: option 'allow_large_os_pages': 2
mimalloc: option 'reserve_huge_os_pages': 0
mimalloc: option 'reserve_huge_os_pages_at': -1
mimalloc: option 'reserve_os_memory': 0 KiB
mimalloc: option 'deprecated_segment_cache': 0
mimalloc: option 'deprecated_page_reset': 0
mimalloc: option 'abandoned_page_purge': 0
mimalloc: option 'deprecated_segment_reset': 0
mimalloc: option 'eager_commit_delay': 1
mimalloc: option 'purge_delay': 1000
mimalloc: option 'use_numa_nodes': 0
mimalloc: option 'disallow_os_alloc': 0
mimalloc: option 'os_tag': 100
mimalloc: option 'max_errors': 32
mimalloc: option 'max_warnings': 32
mimalloc: option 'deprecated_max_segment_reclaim': 10
mimalloc: option 'destroy_on_exit': 0
mimalloc: option 'arena_reserve': 1048576 KiB
mimalloc: option 'arena_purge_mult': 1
mimalloc: option 'deprecated_purge_extend_delay': 1
mimalloc: option 'disallow_arena_alloc': 0
mimalloc: option 'retry_on_oom': 400
mimalloc: option 'visit_abandoned': 0
mimalloc: option 'guarded_min': 0
mimalloc: option 'guarded_max': 1073741824
mimalloc: option 'guarded_precise': 0
mimalloc: option 'guarded_sample_rate': 0
mimalloc: option 'guarded_sample_seed': 0
mimalloc: option 'generic_collect': 10000
mimalloc: option 'page_reclaim_on_free': 0
mimalloc: option 'page_full_retain': 2
mimalloc: option 'page_max_candidates': 4
mimalloc: option 'max_vabits': 0
mimalloc: option 'pagemap_commit': 0
mimalloc: option 'page_commit_on_demand': 0
mimalloc: option 'page_max_reclaim': -1
mimalloc: option 'page_cross_thread_max_reclaim': 32
mimalloc: debug level : 0
mimalloc: secure level: 0
mimalloc: mem tracking: none
mimalloc: reserved 1048576 KiB memory
mimalloc: using 1 numa regions
heap stats: peak total current block total#
reserved: 1.0 GiB 1.0 GiB 1.0 GiB
committed: 58.3 MiB 58.5 MiB 32.5 MiB
reset: 0
purged: 25.8 MiB
touched: 0 0 0 ok
pages: 2.8 Mi 2.8 Mi 1 not all freed
-abandoned: 1.1 Ki 2.8 Mi 1 not all freed
-reclaima: 4
-reclaimf: 0
-reabandon: 0
-waits: 0
-extended: 0
-retire: 0
arenas: 1
-rollback: 0
mmaps: 6
commits: 0
resets: 0
purges: 95
guarded: 0
threads: 24 24 0 ok
searches: 1.0 avg
numa nodes: 1
elapsed: 8.134 s
process: user: 190.900 s, system: 0.236 s, faults: 0, rss: 21.5 MiB, commit: 58.3 MiB
mimalloc: process done: 0x74B7A70D5780
........................
took: 8134 ms
gsum: 3856
rust mimalloc v2
Finished `release` profile [optimized] target(s) in 0.33s
Running `/home/michael/projects/mimalloc-rust-tests/target/release/rust-bench`
mimalloc: v2.2.4 (built on Dec 6 2025, 16:20:36)
mimalloc: option 'show_errors': 0
mimalloc: option 'show_stats': 1
mimalloc: option 'verbose': 1
mimalloc: option 'eager_commit': 1
mimalloc: option 'arena_eager_commit': 2
mimalloc: option 'purge_decommits': 1
mimalloc: option 'allow_large_os_pages': 2
mimalloc: option 'reserve_huge_os_pages': 0
mimalloc: option 'reserve_huge_os_pages_at': -1
mimalloc: option 'reserve_os_memory': 0 KiB
mimalloc: option 'deprecated_segment_cache': 0
mimalloc: option 'deprecated_page_reset': 0
mimalloc: option 'abandoned_page_purge': 0
mimalloc: option 'deprecated_segment_reset': 0
mimalloc: option 'eager_commit_delay': 1
mimalloc: option 'purge_delay': 10
mimalloc: option 'use_numa_nodes': 0
mimalloc: option 'disallow_os_alloc': 0
mimalloc: option 'os_tag': 100
mimalloc: option 'max_errors': 32
mimalloc: option 'max_warnings': 32
mimalloc: option 'max_segment_reclaim': 10
mimalloc: option 'destroy_on_exit': 0
mimalloc: option 'arena_reserve': 1048576 KiB
mimalloc: option 'arena_purge_mult': 10
mimalloc: option 'purge_extend_delay': 1
mimalloc: option 'abandoned_reclaim_on_free': 0
mimalloc: option 'disallow_arena_alloc': 0
mimalloc: option 'retry_on_oom': 400
mimalloc: option 'visit_abandoned': 0
mimalloc: option 'guarded_min': 0
mimalloc: option 'guarded_max': 1073741824
mimalloc: option 'guarded_precise': 0
mimalloc: option 'guarded_sample_rate': 0
mimalloc: option 'guarded_sample_seed': 0
mimalloc: option 'target_segments_per_thread': 0
mimalloc: option 'generic_collect': 10000
mimalloc: debug level : 0
mimalloc: secure level: 0
mimalloc: mem tracking: none
mimalloc: process init: 0x75D82775A780
mimalloc: using 1 numa regions
mimalloc: reserved 1048576 KiB memory
........................
took: 698
gsum: 3960
heap stats: peak total current block total#
reserved: 1.0 GiB 1.0 GiB 1.0 GiB
committed: 1.0 GiB 1.0 GiB 224.1 MiB
reset: 0
purged: 799.8 MiB
touched: 69.6 MiB 96.4 MiB -560.5 GiB
segments: 1.1 Ki 1.5 Ki 1 not all freed
-abandoned: 3 11 0 ok
-cached: 0 0 0 ok
pages: 0 0 -2.8 Mi not all freed
-abandoned: 4 13 0 ok
-extended: 0
-retire: 0
arenas: 1
-rollback: 0
mmaps: 25
commits: 0
resets: 0
purges: 3
guarded: 0
threads: 24 24 0 ok
searches: 0.0 avg
numa nodes: 1
elapsed: 0.699 s
process: user: 16.312 s, system: 0.182 s, faults: 0, rss: 52.6 MiB, commit: 1.0 GiB
mimalloc: process done: 0x75D82775A780
rust mimalloc v3
mimalloc: v3.1.5 (built on Dec 6 2025, 16:21:16)
mimalloc: option 'show_errors': 0
mimalloc: option 'show_stats': 1
mimalloc: option 'verbose': 1
mimalloc: option 'eager_commit': 1
mimalloc: option 'arena_eager_commit': 2
mimalloc: option 'purge_decommits': 1
mimalloc: option 'allow_large_os_pages': 2
mimalloc: option 'reserve_huge_os_pages': 0
mimalloc: option 'reserve_huge_os_pages_at': -1
mimalloc: option 'reserve_os_memory': 0 KiB
mimalloc: option 'deprecated_segment_cache': 0
mimalloc: option 'deprecated_page_reset': 0
mimalloc: option 'abandoned_page_purge': 0
mimalloc: option 'deprecated_segment_reset': 0
mimalloc: option 'eager_commit_delay': 1
mimalloc: option 'purge_delay': 1000
mimalloc: option 'use_numa_nodes': 0
mimalloc: option 'disallow_os_alloc': 0
mimalloc: option 'os_tag': 100
mimalloc: option 'max_errors': 32
mimalloc: option 'max_warnings': 32
mimalloc: option 'deprecated_max_segment_reclaim': 10
mimalloc: option 'destroy_on_exit': 0
mimalloc: option 'arena_reserve': 1048576 KiB
mimalloc: option 'arena_purge_mult': 1
mimalloc: option 'deprecated_purge_extend_delay': 1
mimalloc: option 'disallow_arena_alloc': 0
mimalloc: option 'retry_on_oom': 400
mimalloc: option 'visit_abandoned': 0
mimalloc: option 'guarded_min': 0
mimalloc: option 'guarded_max': 1073741824
mimalloc: option 'guarded_precise': 0
mimalloc: option 'guarded_sample_rate': 0
mimalloc: option 'guarded_sample_seed': 0
mimalloc: option 'generic_collect': 10000
mimalloc: option 'page_reclaim_on_free': 0
mimalloc: option 'page_full_retain': 2
mimalloc: option 'page_max_candidates': 4
mimalloc: option 'max_vabits': 0
mimalloc: option 'pagemap_commit': 0
mimalloc: option 'page_commit_on_demand': 0
mimalloc: option 'page_max_reclaim': -1
mimalloc: option 'page_cross_thread_max_reclaim': 32
mimalloc: debug level : 0
mimalloc: secure level: 0
mimalloc: mem tracking: none
mimalloc: process init: 0x79BBB2BAB7C0
mimalloc: reserved 1048576 KiB memory
mimalloc: using 1 numa regions
........................
took: 8212
gsum: 3906
heap stats: peak total current block total#
reserved: 1.0 GiB 1.0 GiB 1.0 GiB
committed: 64.6 MiB 64.6 MiB -128.5 KiB
reset: 0
purged: 64.7 MiB
touched: 0 0 0 ok
pages: 2.8 Mi 2.8 Mi 2 not all freed
-abandoned: 1.1 Ki 2.8 Mi 0 ok
-reclaima: 0
-reclaimf: 0
-reabandon: 0
-waits: 0
-extended: 0
-retire: 0
arenas: 1
-rollback: 0
mmaps: 3
commits: 0
resets: 0
purges: 229
guarded: 0
threads: 24 24 0 ok
searches: 1.0 avg
numa nodes: 1
elapsed: 8.217 s
process: user: 193.125 s, system: 0.223 s, faults: 0, rss: 31.6 MiB, commit: 64.6 MiB
mimalloc: process done: 0x79BBB2BAB7C0
