mirror of
https://github.com/MariaDB/server.git
synced 2025-11-07 06:16:30 +01:00
a7f0d79f8c
Any InnoDB write workload is marking data pages in the buffer pool dirty. To make the changes durable, it suffices to write to the write-ahead log to facilitate crash recovery. The longer we keep pages dirty in the buffer pool, the better, because the same pages could be modified again and a single write to the file system could cover several changes. Eventually, we must write out dirty pages, so that we can advance the log checkpoint, that is, allow the start of the recovery log to be discarded. (On a clean shutdown, a full checkpoint to the end of the log will be made.) A write workload can be bound by innodb_buffer_pool_size (we must write out changes and evict data pages to make room for others) or by innodb_log_file_size (we must advance the log checkpoint before the tail of the circular ib_logfile0 would overwrite the previous checkpoint). In innodb_log_file_size bound workloads, we failed to set an optimal target for the next checkpoint LSN. If we write out too few pages, then all writer threads may occasionally be blocked in log_free_check() while the buf_flush_page_cleaner() thread is resolving the situation. If we write out too many pages, then the I/O subsystem will be loaded unnecessarily and there will be some write amplification in case some of the unnecessarily written pages would be modified soon afterwards. log_close(): Return the target LSN for buf_flush_ahead(lsn), bitwise-ORed with the "furious" flag, or the special values 0 indicating that no flushing is needed, which is the usual case. log_checkpoint_margin(): Use a similar page checkpoint target as log_close() for the !not_furious case. mtr_flush_ahead(): A wrapper for buf_flush_ahead(). mtr_t::commit_log_release(): Make some common code non-inline in order to reduce code duplication. buf_flush_ahead(lsn, furious=false): Avoid an unnecessary wake-up of the page cleaner if it is scheduled to wake up once per second. Co-developed-by: Alessandro Vetere Reviewed by: Vladislav Lesin |
||
|---|---|---|
| .. | ||
| mtr0mtr.cc | ||