>From 7c8b13a6eeb257d8cadf965b4d46b838fe3a5460 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Fri, 3 Oct 2014 15:48:42 +0300 Subject: [PATCH 2/2] Move the CRC calculations into the other loop through XLogRecDatas. For some reason, this makes a big difference to performance of a simple test case that does a lot of heap insertions to a narrow table. --- src/backend/access/transam/xlog.c | 20 +------------------- src/backend/access/transam/xloginsert.c | 17 ++++++++++++++--- 2 files changed, 15 insertions(+), 22 deletions(-) diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 5dec637..d1b874d 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -859,7 +859,6 @@ XLogRecPtr XLogInsertRecData(XLogRecData *rdata, bool fpw_sensitive) { XLogCtlInsert *Insert = &XLogCtl->Insert; - XLogRecData *rdt; pg_crc32 rdata_crc; bool inserted; XLogRecord *rechdr = (XLogRecord *) rdata->data; @@ -894,24 +893,6 @@ XLogInsertRecData(XLogRecData *rdata, bool fpw_sensitive) if (rechdr->xl_len == 0 && !isLogSwitch) elog(PANIC, "invalid xlog record length %u", rechdr->xl_len); - /* - * Calculate CRC of the data, including all the backup blocks - * - * Note that the record header isn't added into the CRC initially since we - * don't know the prev-link yet. Thus, the CRC will represent the CRC of - * the whole record in the order: rdata, then backup blocks, then record - * header. - */ - INIT_CRC32(rdata_crc); - for (rdt = rdata->next; rdt != NULL; rdt = rdt->next) - COMP_CRC32(rdata_crc, rdt->data, rdt->len); - - /* - * Calculate CRC of the header, except for prev-link, because we don't - * know it yet. It will be added later. - */ - COMP_CRC32(rdata_crc, ((char *) rechdr), offsetof(XLogRecord, xl_prev)); - /*---------- * * We have now done all the preparatory work we can without holding a @@ -1014,6 +995,7 @@ XLogInsertRecData(XLogRecData *rdata, bool fpw_sensitive) * Now that xl_prev has been filled in, finish CRC calculation of the * record header. */ + rdata_crc = rechdr->xl_crc; COMP_CRC32(rdata_crc, ((char *) &rechdr->xl_prev), sizeof(XLogRecPtr)); FIN_CRC32(rdata_crc); rechdr->xl_crc = rdata_crc; diff --git a/src/backend/access/transam/xloginsert.c b/src/backend/access/transam/xloginsert.c index c5be328..d9a2be09 100644 --- a/src/backend/access/transam/xloginsert.c +++ b/src/backend/access/transam/xloginsert.c @@ -130,6 +130,7 @@ XLogRecordAssemble(RmgrId rmid, uint8 info, XLogRecData *rdata, uint32 len, total_len; unsigned i; + pg_crc32 rdata_crc; /* * These need to be static because they are returned to the caller as part @@ -171,6 +172,8 @@ XLogRecordAssemble(RmgrId rmid, uint8 info, XLogRecData *rdata, dtbuf_bkp[i] = false; } + INIT_CRC32(rdata_crc); + *page_writes_omitted = false; len = 0; for (rdt = rdata;;) @@ -235,6 +238,7 @@ XLogRecordAssemble(RmgrId rmid, uint8 info, XLogRecData *rdata, elog(PANIC, "can backup at most %d blocks per xlog record", XLR_MAX_BKP_BLOCKS); } + COMP_CRC32(rdata_crc, rdt->data, rdt->len); /* Break out of loop when rdt points to last chain item */ if (rdt->next == NULL) break; @@ -274,6 +278,7 @@ XLogRecordAssemble(RmgrId rmid, uint8 info, XLogRecData *rdata, rdt->data = (char *) bkpb; rdt->len = sizeof(BkpBlock); total_len += sizeof(BkpBlock); + COMP_CRC32(rdata_crc, rdt->data, rdt->len); rdt->next = &(dtbuf_rdt2[i]); rdt = rdt->next; @@ -284,6 +289,7 @@ XLogRecordAssemble(RmgrId rmid, uint8 info, XLogRecData *rdata, rdt->len = BLCKSZ; total_len += BLCKSZ; rdt->next = NULL; + COMP_CRC32(rdata_crc, rdt->data, rdt->len); } else { @@ -291,6 +297,7 @@ XLogRecordAssemble(RmgrId rmid, uint8 info, XLogRecData *rdata, rdt->data = page; rdt->len = bkpb->hole_offset; total_len += bkpb->hole_offset; + COMP_CRC32(rdata_crc, rdt->data, rdt->len); rdt->next = &(dtbuf_rdt3[i]); rdt = rdt->next; @@ -299,13 +306,14 @@ XLogRecordAssemble(RmgrId rmid, uint8 info, XLogRecData *rdata, rdt->len = BLCKSZ - (bkpb->hole_offset + bkpb->hole_length); total_len += rdt->len; rdt->next = NULL; + COMP_CRC32(rdata_crc, rdt->data, rdt->len); } } /* - * Fill in the fields in the record header. Prev-link is filled in later, - * once we know where in the WAL the record will be inserted. CRC is also - * not calculated yet. + * Fill in the fields in the record header, except for the prev-link + * because we don't know it yet. It will be filled in and added to the + * CRC later, in XLogInsertRecData. */ rechdr->xl_xid = GetCurrentTransactionIdIfAny(); rechdr->xl_tot_len = total_len; @@ -314,6 +322,9 @@ XLogRecordAssemble(RmgrId rmid, uint8 info, XLogRecData *rdata, rechdr->xl_rmid = rmid; rechdr->xl_prev = InvalidXLogRecPtr; + COMP_CRC32(rdata_crc, ((char *) rechdr), offsetof(XLogRecord, xl_prev)); + rechdr->xl_crc = rdata_crc; + return &hdr_rdt; } -- 2.1.1