From 9a054c86d8fe6fb84291cc4076d44adf4ed99cf5 Mon Sep 17 00:00:00 2001 From: Takashi Menjo Date: Thu, 11 Mar 2021 17:55:53 +0900 Subject: [PATCH v9 02/10] Add wal_pmem_map to GUC Fixes introduced in patchset v8: - Let wal_pmem_map be constant unless --with-libpmem - Comment for constant wal_pmem_map --- src/backend/access/transam/xlog.c | 54 ++++++++++++++++++++++++------- src/backend/utils/misc/guc.c | 14 ++++++++ src/include/access/xlog.h | 12 +++++++ 3 files changed, 69 insertions(+), 11 deletions(-) diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 4ac3871c74..f6a08713ea 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -135,6 +135,10 @@ int wal_retrieve_retry_interval = 5000; int max_slot_wal_keep_size_mb = -1; bool track_wal_io_timing = false; +#ifdef USE_LIBPMEM +bool wal_pmem_map = false; +#endif + #ifdef WAL_DEBUG bool XLOG_DEBUG = false; #endif @@ -4363,13 +4367,28 @@ XLOGShmemSize(void) { Size size; + /* + * If we use WAL segment files as WAL buffers, we don't use the given + * value of wal_buffers. Instead, we set it to the value based on the + * segment size and the page size. This should be done before calculating + * the size of xlblocks array. + */ + if (wal_pmem_map) + { + int npages; + char buf[32]; + + npages = wal_segment_size / XLOG_BLCKSZ; + snprintf(buf, sizeof(buf), "%d", (int) npages); + SetConfigOption("wal_buffers", buf, PGC_POSTMASTER, PGC_S_OVERRIDE); + } /* * If the value of wal_buffers is -1, use the preferred auto-tune value. * This isn't an amazingly clean place to do this, but we must wait till * NBuffers has received its final value, and must do it before using the * value of XLOGbuffers to do anything important. */ - if (XLOGbuffers == -1) + else if (XLOGbuffers == -1) { char buf[32]; @@ -4385,10 +4404,17 @@ XLOGShmemSize(void) size = add_size(size, mul_size(sizeof(WALInsertLockPadded), NUM_XLOGINSERT_LOCKS + 1)); /* xlblocks array */ size = add_size(size, mul_size(sizeof(XLogRecPtr), XLOGbuffers)); - /* extra alignment padding for XLOG I/O buffers */ - size = add_size(size, XLOG_BLCKSZ); - /* and the buffers themselves */ - size = add_size(size, mul_size(XLOG_BLCKSZ, XLOGbuffers)); + + /* + * If we use WAL segment files as WAL buffers, we don't need volatile ones. + */ + if (!wal_pmem_map) + { + /* extra alignment padding for XLOG I/O buffers */ + size = add_size(size, XLOG_BLCKSZ); + /* and the buffers themselves */ + size = add_size(size, mul_size(XLOG_BLCKSZ, XLOGbuffers)); + } /* * Note: we don't count ControlFileData, it comes out of the "slop factor" @@ -4482,13 +4508,19 @@ XLOGShmemInit(void) } /* - * Align the start of the page buffers to a full xlog block size boundary. - * This simplifies some calculations in XLOG insertion. It is also - * required for O_DIRECT. + * If we use WAL segment files as WAL buffers, we don't need volatile ones. */ - allocptr = (char *) TYPEALIGN(XLOG_BLCKSZ, allocptr); - XLogCtl->pages = allocptr; - memset(XLogCtl->pages, 0, (Size) XLOG_BLCKSZ * XLOGbuffers); + if (!wal_pmem_map) + { + /* + * Align the start of the page buffers to a full xlog block size boundary. + * This simplifies some calculations in XLOG insertion. It is also + * required for O_DIRECT. + */ + allocptr = (char *) TYPEALIGN(XLOG_BLCKSZ, allocptr); + XLogCtl->pages = allocptr; + memset(XLogCtl->pages, 0, (Size) XLOG_BLCKSZ * XLOGbuffers); + } /* * Do basic initialization of XLogCtl shared data. (StartupXLOG will fill diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index 932aefc777..5268cd95f4 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -1353,6 +1353,20 @@ static struct config_bool ConfigureNamesBool[] = NULL, NULL, NULL }, +#ifdef USE_LIBPMEM + { + {"wal_pmem_map", PGC_POSTMASTER, WAL_SETTINGS, + gettext_noop("Map WAL segment files on PMEM as WAL buffers."), + gettext_noop("If true, postgres will memory-map WAL segment files " + "on PMEM to use them as WAL buffers instead of the " + "traditional volatile ones."), + }, + &wal_pmem_map, + false, + NULL, NULL, NULL + }, +#endif + { {"log_checkpoints", PGC_SIGHUP, LOGGING_WHAT, gettext_noop("Logs each checkpoint."), diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 09f6464331..9813e65e3e 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -51,6 +51,18 @@ extern char *wal_consistency_checking_string; extern bool log_checkpoints; extern bool track_wal_io_timing; +#ifdef USE_LIBPMEM +extern bool wal_pmem_map; +#else +/* + * If USE_LIBPMEM is not defined (that is, no --with-libpmem), wal_pmem_map + * is always false and is never used essentially. Using #if(n)def everywhere + * is not good for code readability, so let wal_pmem_map be constant. This + * may help compilers optimize conditional branches. + */ +#define wal_pmem_map false +#endif + extern int CheckPointSegments; /* Archive modes */ -- 2.25.1