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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_journal.cpp
+21 -7
View File
@@ -22,6 +22,11 @@ int blockstore_journal_check_t::check_available(blockstore_op_t *op, int require
next_in_pos += fits * size;
sectors_required++;
}
else if (bs->journal.sector_info[next_sector].dirty)
{
// sectors_required is more like "sectors to write"
sectors_required++;
}
if (required <= 0)
{
break;
@@ -33,13 +38,19 @@ int blockstore_journal_check_t::check_available(blockstore_op_t *op, int require
right_dir = false;
}
next_in_pos = 0;
if (bs->journal.sector_info[next_sector].usage_count > 0)
if (bs->journal.sector_info[next_sector].usage_count > 0 ||
bs->journal.sector_info[next_sector].dirty)
{
next_sector = ((next_sector + 1) % bs->journal.sector_count);
}
if (bs->journal.sector_info[next_sector].usage_count > 0)
if (bs->journal.sector_info[next_sector].usage_count > 0 ||
bs->journal.sector_info[next_sector].dirty)
{
// No memory buffer available. Wait for it.
#ifdef BLOCKSTORE_DEBUG
printf("next journal buffer %d is still dirty=%d used=%d\n", next_sector,
bs->journal.sector_info[next_sector].dirty, bs->journal.sector_info[next_sector].usage_count);
#endif
PRIV(op)->wait_for = WAIT_JOURNAL_BUFFER;
return 0;
}
@@ -68,6 +79,7 @@ journal_entry* prefill_single_journal_entry(journal_t & journal, uint16_t type,
{
if (JOURNAL_BLOCK_SIZE - journal.in_sector_pos < size)
{
assert(!journal.sector_info[journal.cur_sector].dirty);
// Move to the next journal sector
if (journal.sector_info[journal.cur_sector].usage_count > 0)
{
@@ -91,22 +103,24 @@ journal_entry* prefill_single_journal_entry(journal_t & journal, uint16_t type,
je->type = type;
je->size = size;
je->crc32_prev = journal.crc32_last;
journal.sector_info[journal.cur_sector].dirty = true;
return je;
}
void prepare_journal_sector_write(journal_t & journal, io_uring_sqe *sqe, std::function<void(ring_data_t*)> cb)
void prepare_journal_sector_write(journal_t & journal, int cur_sector, io_uring_sqe *sqe, std::function<void(ring_data_t*)> cb)
{
journal.sector_info[journal.cur_sector].usage_count++;
journal.sector_info[cur_sector].dirty = false;
journal.sector_info[cur_sector].usage_count++;
ring_data_t *data = ((ring_data_t*)sqe->user_data);
data->iov = (struct iovec){
(journal.inmemory
? journal.buffer + journal.sector_info[journal.cur_sector].offset
: journal.sector_buf + JOURNAL_BLOCK_SIZE*journal.cur_sector),
? journal.buffer + journal.sector_info[cur_sector].offset
: journal.sector_buf + JOURNAL_BLOCK_SIZE*cur_sector),
JOURNAL_BLOCK_SIZE
};
data->callback = cb;
my_uring_prep_writev(
sqe, journal.fd, &data->iov, 1, journal.offset + journal.sector_info[journal.cur_sector].offset
sqe, journal.fd, &data->iov, 1, journal.offset + journal.sector_info[cur_sector].offset
);
}