The commit includes two things: a backport of a feature from MySQL 5.7 to AliSQL 5.6, and a change to split a "processed blocks" counter into "flushed blocks" and "evicted blocks" counters.

MariaDB 10.2+ is based on MySQL 5.7, so the only addition of this contribution is the split of the counter. I would prefer to do it differently, if it is OK from a performance point of view:

1. Move the counters from innodb_monitor to server status variables (export_vars).
2. Instead of passing the counters as return values or output parameters, just do my_atomic_add(&export_vars.counter_name, ...) at the low level.

plinux, I think that the above is feasible to do in MariaDB 10.3.

In MDEV-23399, the LRU eviction flushing was moved from the single page cleaner thread to user threads that are allocating buffer pool pages.

I would not extend the monitor interface with new counters; that interface should hopefully be removed (MDEV-15706) and replaced with innodb_status_variables.

We actually do have MONITOR_LRU_BATCH_EVICT_TOTAL_PAGE, which is being incremented in buf_do_LRU_batch() (and not exposed elsewhere). We also have a buf_flush_page_count (innodb_buffer_pool_pages_flushed) that is incremented in each call of buf_flush_page(). That counter does not distinguish the two types of page writes (checkpoint or eviction).

It seems that we could address this by extending innodb_status_variables as follows:

• Exposing the MONITOR_LRU_BATCH_EVICT_TOTAL_PAGE counter.
• Introducing a new counter of page writes triggered by eviction flushing, updated while holding buf_pool.mutex or buf_pool.flush_list_mutex in buf_do_LRU_batch() or buf_flush_LRU_list_batch() or buf_page_write_complete().

bb-10.6-MDEV-11384

Looks good to me,

wlad, thank you. I filed MDEV-25085 for the change of instrumentation, because it has rather little to do with the original Description. Once that is closed, I intend to close this ticket as well, because then everything mentioned in the Description would be addressed.

The first part (MySQL WL#7047) was already part of MariaDB Server 10.2 (via MySQL 5.7). The second part (the counters) were mostly done in MariaDB 10.5.7 (MDEV-23399 and MDEV-23855), with a last bit (MDEV-25085) done in MariaDB 10.6.0.