2026-05-09T00:42:52.737520000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (main 57ef219*) % sudo dtrace -q -Z -x dynvarsize=64m -x bufsize=128m \
    -c "./python.exe -m profiling.sampling run -r 1000khz -d 15 --pstats -o /dev/null /tmp/busy.py" \
    -n '
  pid$target::*get_stack_trace*:entry  { self->gst = timestamp; }
  pid$target::*get_stack_trace*:return /self->gst/ {
      @gst_avg = avg(timestamp - self->gst);
      @gst_n = count(); self->gst = 0;
  }

  pid$target::mach_vm_read_overwrite:entry {
      self->vmr = timestamp;
      @vmr_size[arg2] = count();
  }

  pid$target::mach_vm_read_overwrite:return /self->vmr/ {
      @vmr_avg = avg(timestamp - self->vmr);
      @vmr_n = count();
      self->vmr = 0;
  }

  END {
    printf("\n=== get_stack_trace ===\n");
    printf("avg ns "); printa(@gst_avg); printf("count "); printa(@gst_n);
    printf("\n=== mach_vm_read_overwrite ===\n");
    printf("avg ns "); printa(@vmr_avg); printf("count "); printa(@vmr_n);
    printf("\n=== mach_vm_read_overwrite read sizes (bytes) ===\n");
    printa("%d bytes                                 %@d\n", @vmr_size);
  }'

Captured 897,532 samples in 15.00 seconds
Sample rate: 59,835.42 samples/sec
Error rate: 0.00
Raw unwinder rate: 69,908.92 samples/sec (14.30 us/sample)
Warning: missed 14102479 samples from the expected total of 15000011 (94.02%)

=== get_stack_trace ===
avg ns 
            13104
count 
           911514

=== mach_vm_read_overwrite ===
avg ns 
             3137
count 
          2734564

=== mach_vm_read_overwrite read sizes (bytes) ===
880 bytes                                 1
8 bytes                                 2
16384 bytes                                 2734561

2026-05-09T00:43:11.123030000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (main 57ef219*) % cat /tmp/busy.py 
x = 0
while True:
    x = (x + 1) % 1000003
2026-05-09T00:43:22.664550000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (main 57ef219*) % git diff
diff --git i/Lib/profiling/sampling/sample.py w/Lib/profiling/sampling/sample.py
index 5bbe2483581..36ed33337aa 100644
--- i/Lib/profiling/sampling/sample.py
+++ w/Lib/profiling/sampling/sample.py
@@ -181,6 +181,19 @@ def sample(self, collector, duration_sec=None, *, async_aware=False):
             print(f"Sample rate: {fmt(sample_rate, 2)} samples/sec")
             print(f"Error rate: {fmt(error_rate, 2)}")
 
+            # Raw RemoteUnwinder() throughput (tight loop, no scheduler/sleep)
+            try:
+                raw_start = time.perf_counter()
+                raw_n = 0
+                while time.perf_counter() - raw_start < 0.2:
+                    self._get_stack_trace(async_aware=async_aware)
+                    raw_n += 1
+                raw_elapsed = time.perf_counter() - raw_start
+                if raw_n and raw_elapsed:
+                    print(f"Raw unwinder rate: {fmt(raw_n/raw_elapsed, 2)} samples/sec ({fmt(1e6*raw_elapsed/raw_n, 2)} us/sample)")
+            except Exception:
+                pass
+
             # Print unwinder stats if stats collection is enabled
             if self.collect_stats:
                 self._print_unwinder_stats()
2026-05-09T00:43:23.960838000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (main 57ef219*) % 

[130] 2026-05-09T00:44:06.004867000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (main 57ef219*) % cat /tmp/vmread_bench.c 
#include <mach/mach.h>
#include <mach/mach_vm.h>
#include <stdio.h>
#include <time.h>

int main(void) {
    char src[16384] = {0}, dst[16384];
    mach_port_t self = mach_task_self();
    mach_vm_size_t out;

    for (size_t sz = 64; sz <= 16384; sz *= 2) {
        uint64_t t0 = clock_gettime_nsec_np(CLOCK_UPTIME_RAW);
        for (int i = 0; i < 100000; i++)
            mach_vm_read_overwrite(self, (mach_vm_address_t)src, sz,
                                   (mach_vm_address_t)dst, &out);
        uint64_t t1 = clock_gettime_nsec_np(CLOCK_UPTIME_RAW);
        printf("%6zu B: %.0f ns/op\n", sz, (t1 - t0) / 100000.0);
    }
}
2026-05-09T00:44:06.177740000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (main 57ef219*) % cc /tmp/vmread_bench.c -o /tmp/vmread_bench 
2026-05-09T00:44:14.349092000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (main 57ef219*) % /tmp/vmread_bench 
    64 B: 635 ns/op
   128 B: 388 ns/op
   256 B: 358 ns/op
   512 B: 371 ns/op
  1024 B: 391 ns/op
  2048 B: 415 ns/op
  4096 B: 489 ns/op
  8192 B: 651 ns/op
 16384 B: 938 ns/op

2026-05-08T22:53:09.556034847+0000 maurycy@weiss /home/maurycy/cpython (main 57ef219*) # cat /tmp/vm_readv_bench.c 
#define _GNU_SOURCE
#include <stdio.h>
#include <sys/uio.h>
#include <time.h>
#include <unistd.h>

int main(void) {
    char src[16384] = {0}, dst[16384];
    pid_t self = getpid();

    for (size_t sz = 64; sz <= 16384; sz *= 2) {
        struct iovec local  = {dst, sz};
        struct iovec remote = {src, sz};
        struct timespec t0, t1;
        clock_gettime(CLOCK_MONOTONIC, &t0);
        for (int i = 0; i < 100000; i++)
            process_vm_readv(self, &local, 1, &remote, 1, 0);
        clock_gettime(CLOCK_MONOTONIC, &t1);
        long ns = (t1.tv_sec - t0.tv_sec) * 1000000000L
                + (t1.tv_nsec - t0.tv_nsec);
        printf("%6zu B: %ld ns/op\n", sz, ns / 100000);
    }
}
2026-05-08T22:53:09.928097987+0000 maurycy@weiss /home/maurycy/cpython (main 57ef219*) # cc /tmp/vm_readv_bench.c -o /tmp/vm_readv_bench
2026-05-08T22:53:24.934249589+0000 maurycy@weiss /home/maurycy/cpython (main 57ef219*) # /tmp/vm_readv_bench                        
    64 B: 434 ns/op
   128 B: 285 ns/op
   256 B: 250 ns/op
   512 B: 256 ns/op
  1024 B: 265 ns/op
  2048 B: 329 ns/op
  4096 B: 369 ns/op
  8192 B: 493 ns/op
 16384 B: 779 ns/op

[130] 2026-05-09T01:08:09.192039000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (remote-debugging-no-paged 7606bb1*) % sudo -E ./python.exe -m profiling.sampling run -r 1000khz -d 15 --pstats -o /dev/null /tmp/busy.py
Captured 2,657,910 samples in 15.00 seconds
Sample rate: 177,193.96 samples/sec
Error rate: 0.00
Raw unwinder rate: 297,398.45 samples/sec (3.36 us/sample)
Warning: missed 12342093 samples from the expected total of 15000003 (82.28%)
2026-05-09T01:08:28.996839000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (remote-debugging-no-paged 7606bb1*) % 

2026-05-09T01:12:48.469595000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (main 57ef219*) % sudo -E ./python.exe -m profiling.sampling run -r 1000khz -d 15 --pstats -o /dev/null /tmp/busy.py
Captured 1,687,897 samples in 15.00 seconds
Sample rate: 112,526.41 samples/sec
Error rate: 0.00
Raw unwinder rate: 132,402.68 samples/sec (7.55 us/sample)
Warning: missed 13312110 samples from the expected total of 15000007 (88.75%)