Hi Sage,
I was trying to benchmark bluestore by enabling bluestore_sync_transaction and it seems the db method in the below code is called wrongly ?
If we enable bluestore_sync_submit_transaction , shouldn't we be doing db-> submit_transaction_sync() and if we enable only bluestore_sync_transaction shouldn't we be doing db->submit_transaction() ?
if (!g_conf->bluestore_sync_transaction) {
if (g_conf->bluestore_sync_submit_transaction) {
_txc_finalize_kv(txc, txc->t);
int r = db->submit_transaction(txc->t);
assert(r == 0);
}
} else {
_txc_finalize_kv(txc, txc->t);
int r = db->submit_transaction_sync(txc->t);
assert(r == 0);
}
We are anyway calling one submit_transaction_sync from _kv_sync_thread().
Now, if I do that (for bluestore_sync_transaction = true) , I am seeing ~10% performance improvement with min_alloc_size = 16K and seeing much lower cpu usage with _kv_sync_thread.
This is also telling us that even if we are not utilizing 100% cpu core for _kv_sync_thread , more work you do from this thread will degrade performance.
IMO, bluestore_sync_transaction should be default true if you agree that we should be replacing the *_sync call.
Thanks & Regards
Somnath
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