diff options
| author | Tom Lane <tgl@sss.pgh.pa.us> | 2016-11-25 18:36:10 -0500 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2016-11-25 18:36:10 -0500 |
| commit | dbdfd114f34443f1e4ad16ce2721f9817d3b3d80 (patch) | |
| tree | d5dc20edfdddecd14d614aee6c2ac07666ae5fad /src/include/pg_config_manual.h | |
| parent | ab77a5a4561fad847af4a101a29c922c66449870 (diff) | |
Bring some clarity to the defaults for the xxx_flush_after parameters.
Instead of confusingly stating platform-dependent defaults for these
parameters in the comments in postgresql.conf.sample (with the main
entry being a lie on Linux), teach initdb to install the correct
platform-dependent value in postgresql.conf, similarly to the way
we handle other platform-dependent defaults. This won't do anything
for existing 9.6 installations, but since it's effectively only a
documentation improvement, that seems OK.
Since this requires initdb to have access to the default values,
move the #define's for those to pg_config_manual.h; the original
placement in bufmgr.h is unworkable because that file can't be
included by frontend programs.
Adjust the default value for wal_writer_flush_after so that it is 1MB
regardless of XLOG_BLCKSZ, conforming to what is stated in both the
SGML docs and postgresql.conf. (We could alternatively make it scale
with XLOG_BLCKSZ, but I'm not sure I see the point.)
Copy-edit related SGML documentation.
Fabien Coelho and Tom Lane, per a gripe from Tomas Vondra.
Discussion: <30ebc6e3-8358-09cf-44a8-578252938424@2ndquadrant.com>
Diffstat (limited to 'src/include/pg_config_manual.h')
| -rw-r--r-- | src/include/pg_config_manual.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/src/include/pg_config_manual.h b/src/include/pg_config_manual.h index a2b2b614bec..96885bb9901 100644 --- a/src/include/pg_config_manual.h +++ b/src/include/pg_config_manual.h @@ -148,6 +148,24 @@ #endif /* + * Default and maximum values for backend_flush_after, bgwriter_flush_after + * and checkpoint_flush_after; measured in blocks. Currently, these are + * enabled by default if sync_file_range() exists, ie, only on Linux. Perhaps + * we could also enable by default if we have mmap and msync(MS_ASYNC)? + */ +#ifdef HAVE_SYNC_FILE_RANGE +#define DEFAULT_BACKEND_FLUSH_AFTER 0 /* never enabled by default */ +#define DEFAULT_BGWRITER_FLUSH_AFTER 64 +#define DEFAULT_CHECKPOINT_FLUSH_AFTER 32 +#else +#define DEFAULT_BACKEND_FLUSH_AFTER 0 +#define DEFAULT_BGWRITER_FLUSH_AFTER 0 +#define DEFAULT_CHECKPOINT_FLUSH_AFTER 0 +#endif +/* upper limit for all three variables */ +#define WRITEBACK_MAX_PENDING_FLUSHES 256 + +/* * USE_SSL code should be compiled only when compiling with an SSL * implementation. (Currently, only OpenSSL is supported, but we might add * more implementations in the future.) |