Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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10.0(EOL)
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None
Description
When I set my.cnf like this:
innodb_buffer_pool_size = 102400M
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innodb_buffer_pool_dump_at_shutdown=1
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innodb_buffer_pool_dump_now=1
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innodb_buffer_pool_load_at_startup=1
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innodb_buffer_pool_load_now=1
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and use (1-Innodb_buffer_pool_reads/Innodb_buffer_pool_read_requests)*100% to calculate innodb buffer pool hit rate ,I got a number less than zero,like
+----------------------+
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| hit_rate |
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+----------------------+
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| -0.04231484607035707 |
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+----------------------+
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,and
MariaDB [(none)]> show global status like 'innodb_buffer_pool_read%';
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+---------------------------------------+----------+
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| Variable_name | Value |
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+---------------------------------------+----------+
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| Innodb_buffer_pool_read_ahead | 0 |
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| Innodb_buffer_pool_read_ahead_evicted | 0 |
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| Innodb_buffer_pool_read_ahead_rnd | 0 |
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| Innodb_buffer_pool_read_requests | 13973819 |
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| Innodb_buffer_pool_reads | 13979732 |
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+---------------------------------------+----------+
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I found Innodb_buffer_pool_reads is bigger than Innodb_buffer_pool_read_requests!
When the server is loading pages at the start time,I execute show engine innodb status ,and I also see a negative number like:
Buffer pool hit rate 18446744073709549183 / 1000, young-making rate 0 / 1000 not 0 / 1000
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Buffer pool hit rate 18446744073708648991 / 1000, young-making rate 0 / 1000 not 0 / 1000
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Buffer pool hit rate 18446744073709549537 / 1000, young-making rate 0 / 1000 not 0 / 1000
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Buffer pool hit rate 18446744073709551510 / 1000, young-making rate 0 / 1000 not 0 / 1000
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Obviously it's a negative number in unsigned long int.
Attachments
Issue Links
- relates to
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MDEV-21212 buf_page_get_gen -> buf_pool->stat.n_page_gets++ is a cpu waste (0.5-1%)
- Closed