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gh-149584: Do not use page cache for thread/frame/interp reads#149585

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maurycy wants to merge 3 commits intopython:mainfrom
maurycy:remote-debugging-no-paged
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gh-149584: Do not use page cache for thread/frame/interp reads#149585
maurycy wants to merge 3 commits intopython:mainfrom
maurycy:remote-debugging-no-paged

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@maurycy maurycy commented May 8, 2026

Please see gh-149584 for a very detailed investigation.

2026-05-09T01:22:51.167402000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (remote-debugging-no-paged 7606bb1*) % cat /tmp/busy.py 
x = 0
while True:
    x = (x + 1) % 1000003

Before:

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
Warning: missed 13312110 samples from the expected total of 15000007 (88.75%)

After:

[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
Warning: missed 12342093 samples from the expected total of 15000003 (82.28%)

Closes #149584

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_remote_debugging: reading whole pages over and over

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