diff options
| -rw-r--r-- | src/backend/access/transam/xlog.c | 49 |
1 files changed, 31 insertions, 18 deletions
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index ef9b8e4fb96..1952b013fb4 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -2456,35 +2456,44 @@ XLogSetAsyncXactLSN(XLogRecPtr asyncXactLSN) { XLogRecPtr WriteRqstPtr = asyncXactLSN; bool sleeping; + bool wakeup = false; + XLogRecPtr prevAsyncXactLSN; SpinLockAcquire(&XLogCtl->info_lck); LogwrtResult = XLogCtl->LogwrtResult; sleeping = XLogCtl->WalWriterSleeping; + prevAsyncXactLSN = XLogCtl->asyncXactLSN; if (XLogCtl->asyncXactLSN < asyncXactLSN) XLogCtl->asyncXactLSN = asyncXactLSN; SpinLockRelease(&XLogCtl->info_lck); /* - * If the WALWriter is sleeping, we should kick it to make it come out of - * low-power mode. Otherwise, determine whether there's a full page of - * WAL available to write. + * If somebody else already called this function with a more aggressive + * LSN, they will have done what we needed (and perhaps more). */ - if (!sleeping) + if (asyncXactLSN <= prevAsyncXactLSN) + return; + + /* + * If the WALWriter is sleeping, kick it to make it come out of low-power + * mode, so that this async commit will reach disk within the expected + * amount of time. Otherwise, determine whether it has enough WAL + * available to flush, the same way that XLogBackgroundFlush() does. + */ + if (sleeping) + wakeup = true; + else { - /* back off to last completed page boundary */ - WriteRqstPtr -= WriteRqstPtr % XLOG_BLCKSZ; + int flushblocks; - /* if we have already flushed that far, we're done */ - if (WriteRqstPtr <= LogwrtResult.Flush) - return; + flushblocks = + WriteRqstPtr / XLOG_BLCKSZ - LogwrtResult.Flush / XLOG_BLCKSZ; + + if (WalWriterFlushAfter == 0 || flushblocks >= WalWriterFlushAfter) + wakeup = true; } - /* - * Nudge the WALWriter: it has a full page of WAL to write, or we want it - * to come out of low-power mode so that this async commit will reach disk - * within the expected amount of time. - */ - if (ProcGlobal->walwriterLatch) + if (wakeup && ProcGlobal->walwriterLatch) SetLatch(ProcGlobal->walwriterLatch); } @@ -2803,7 +2812,7 @@ XLogBackgroundFlush(void) bool flexible = true; static TimestampTz lastflush; TimestampTz now; - int flushbytes; + int flushblocks; TimeLineID insertTLI; /* XLOG doesn't need flushing during recovery */ @@ -2855,9 +2864,13 @@ XLogBackgroundFlush(void) /* * Determine how far to flush WAL, based on the wal_writer_delay and * wal_writer_flush_after GUCs. + * + * Note that XLogSetAsyncXactLSN() performs similar calculation based on + * wal_writer_flush_after, to decide when to wake us up. Make sure the + * logic is the same in both places if you change this. */ now = GetCurrentTimestamp(); - flushbytes = + flushblocks = WriteRqst.Write / XLOG_BLCKSZ - LogwrtResult.Flush / XLOG_BLCKSZ; if (WalWriterFlushAfter == 0 || lastflush == 0) @@ -2876,7 +2889,7 @@ XLogBackgroundFlush(void) WriteRqst.Flush = WriteRqst.Write; lastflush = now; } - else if (flushbytes >= WalWriterFlushAfter) + else if (flushblocks >= WalWriterFlushAfter) { /* exceeded wal_writer_flush_after blocks, flush */ WriteRqst.Flush = WriteRqst.Write; |