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MDEV-23017: Regression due to unwanted read-ahead

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MDEV-15053 inadvertently inverted the condition for invoking
buf_read_ahead_linear().

buf_page_get_low(): Apply the correct condition.

buf_page_optimistic_get(): Remove the read-ahead altogether.
This function should never access a block for the first time.
This commit is contained in:
Marko Mäkelä 2020-07-02 07:45:19 +03:00
parent 1a4846dedc
commit 0fe97c20b3
1 changed files with 3 additions and 10 deletions
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13
storage/innobase/buf/buf0buf.cc
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@ -3516,7 +3516,7 @@ evict_from_pool:
|| mode == BUF_PEEK_IF_IN_POOL || mode == BUF_PEEK_IF_IN_POOL
|| fix_block->page.status != buf_page_t::FREED); || fix_block->page.status != buf_page_t::FREED);
const bool first_access = fix_block->page.set_accessed(); const bool not_first_access = fix_block->page.set_accessed();
if (mode != BUF_PEEK_IF_IN_POOL) { if (mode != BUF_PEEK_IF_IN_POOL) {
buf_page_make_young_if_needed(&fix_block->page); buf_page_make_young_if_needed(&fix_block->page);
@ -3571,7 +3571,7 @@ get_latch:
file, line); file, line);
} }
if (mode != BUF_PEEK_IF_IN_POOL && first_access) { if (!not_first_access && mode != BUF_PEEK_IF_IN_POOL) {
/* In the case of a first access, try to apply linear /* In the case of a first access, try to apply linear
read-ahead */ read-ahead */
@ -3678,7 +3678,7 @@ buf_page_optimistic_get(
buf_block_buf_fix_inc(block, file, line); buf_block_buf_fix_inc(block, file, line);
hash_lock->read_unlock(); hash_lock->read_unlock();
const bool first_access = block->page.set_accessed(); block->page.set_accessed();
buf_page_make_young_if_needed(&block->page); buf_page_make_young_if_needed(&block->page);
@ -3723,13 +3723,6 @@ buf_page_optimistic_get(
ut_ad(block->page.buf_fix_count()); ut_ad(block->page.buf_fix_count());
ut_ad(block->page.state() == BUF_BLOCK_FILE_PAGE); ut_ad(block->page.state() == BUF_BLOCK_FILE_PAGE);
if (first_access) {
/* In the case of a first access, try to apply linear
read-ahead */
buf_read_ahead_linear(block->page.id(), block->zip_size(),
ibuf_inside(mtr));
}
buf_pool.stat.n_page_gets++; buf_pool.stat.n_page_gets++;
return(TRUE); return(TRUE);