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Do not overwrite same journal sector multiple times

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It doesn't reduce actual WA, but it reduces tail latency (Q=32, 10% / 50% / 90% / 99% / 99.95%):
- write: 766us/979us/1090us/1303us/1729us vs 1074us/1450us/2212us/3261us/4113us
- sync: 701us/881us/1188us/1762us/2540us vs 269us/955us/1663us/2638us/4146us
This commit is contained in:
Vitaliy Filippov
2020-01-15 02:53:01 +03:00
parent 111516381f
commit a3d3949dce
7 changed files with 163 additions and 91 deletions
Download Patch File Download Diff File Expand all files Collapse all files
blockstore_stable.cpp
+11 -13
View File
@@ -94,6 +94,14 @@ int blockstore_impl_t::dequeue_stable(blockstore_op_t *op)
// Prepare and submit journal entries
auto cb = [this, op](ring_data_t *data) { handle_stable_event(data, op); };
int s = 0, cur_sector = -1;
if ((JOURNAL_BLOCK_SIZE - journal.in_sector_pos) < sizeof(journal_entry_stable) &&
journal.sector_info[journal.cur_sector].dirty)
{
if (cur_sector == -1)
PRIV(op)->min_used_journal_sector = 1 + journal.cur_sector;
cur_sector = journal.cur_sector;
prepare_journal_sector_write(journal, cur_sector, sqe[s++], cb);
}
for (i = 0, v = (obj_ver_id*)op->buf; i < op->len; i++, v++)
{
auto unstab_it = unstable_writes.find(v->oid);
@@ -104,6 +112,7 @@ int blockstore_impl_t::dequeue_stable(blockstore_op_t *op)
}
journal_entry_stable *je = (journal_entry_stable*)
prefill_single_journal_entry(journal, JE_STABLE, sizeof(journal_entry_stable));
journal.sector_info[journal.cur_sector].dirty = false;
je->oid = v->oid;
je->version = v->version;
je->crc32 = je_crc32((journal_entry*)je);
@@ -113,7 +122,7 @@ int blockstore_impl_t::dequeue_stable(blockstore_op_t *op)
if (cur_sector == -1)
PRIV(op)->min_used_journal_sector = 1 + journal.cur_sector;
cur_sector = journal.cur_sector;
prepare_journal_sector_write(journal, sqe[s++], cb);
prepare_journal_sector_write(journal, cur_sector, sqe[s++], cb);
}
}
PRIV(op)->max_used_journal_sector = 1 + journal.cur_sector;
@@ -135,18 +144,7 @@ void blockstore_impl_t::handle_stable_event(ring_data_t *data, blockstore_op_t *
if (PRIV(op)->pending_ops == 0)
{
// Release used journal sectors
if (PRIV(op)->min_used_journal_sector > 0)
{
uint64_t s = PRIV(op)->min_used_journal_sector;
while (1)
{
journal.sector_info[s-1].usage_count--;
if (s == PRIV(op)->max_used_journal_sector)
break;
s = 1 + s % journal.sector_count;
}
PRIV(op)->min_used_journal_sector = PRIV(op)->max_used_journal_sector = 0;
}
release_journal_sectors(op);
// First step: mark dirty_db entries as stable, acknowledge op completion
obj_ver_id* v;
int i;