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trans_logger: call log_flush() exactly when necessary

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Thomas Schoebel-Theuer 2013-01-03 12:39:48 +01:00 committed by Thomas Schoebel-Theuer
parent 47c8f6ae57
commit 5d3104ec23
1 changed files with 19 additions and 12 deletions
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31
mars_trans_logger.c
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@ -2494,18 +2494,25 @@ void trans_logger_log(struct trans_logger_brick *brick)
ranking_select_done(rkd, winner, nr);
break;
default: ;
}
/* Calling log_flush() too often may result in
* increased overhead (and thus in lower throughput).
* OTOH, calling it too seldom may hold back
* IO completion for the end user for some time.
*/
if (atomic_read(&brick->q_phase[0].q_flying) > 0 &&
(atomic_read(&brick->q_phase[0].q_queued) <= 0 ||
(winner != 0 && _nr_flying_inputs(brick) == 0))) {
_flush_inputs(brick);
default:
/* Performance-critical:
* Calling log_flush() too often may result in
* increased overhead (and thus in lower throughput).
* Call it only when the IO scheduler need no do anything else.
* OTOH, calling it too seldom may hold back
* IO completion for the end user for too long time.
* Be careful to flush any leftovers in the log buffer.
*/
if (
// there is nothing to append any more
atomic_read(&brick->q_phase[0].q_queued) <= 0 &&
// and the user is waiting for an answer
(atomic_read(&brick->log_fly_count) > 0 ||
// else flush any leftovers in background, when there is no other activity
(atomic_read(&brick->q_phase[0].q_flying) + atomic_read(&brick->q_phase[2].q_flying) > 0 &&
atomic_read(&brick->q_phase[1].q_flying) + atomic_read(&brick->q_phase[3].q_flying) <= 0))) {
_flush_inputs(brick);
}
}
/* Update symlinks even during pauses.