> I need to step in and do 2 things: Thanks for posting that. Let me know if you have any questions while doing your testing. I've found that using 16K blocks on FreeBSD results in about an 8% speedup in writes to the database, fwiw.
I'm likely going to make this the default for PostgreSQL on FreeBSD starting with 7.4 (just posted something to -hackers about this)f. If you'd like to do this in your testing, just apply the following patch. Right now PostgreSQL defaults to 8K blocks, but FreeBSD uses 16K blocks which means that currently, reading two blocks of data in PG is two read calls to the OS, one reads 16K of data off disk and returns the 1st page, the 2nd call pulls the 2nd block from the FS cache. In making things 16K, it avoids the need for the 2nd system call which is where the performance difference is coming from, afaikt. -sc -- Sean Chittenden
Index: src/include/pg_config_manual.h =================================================================== RCS file: /home/ncvs/pgsql/pgsql-server/src/include/pg_config_manual.h,v retrieving revision 1.5 diff -u -r1.5 pg_config_manual.h --- src/include/pg_config_manual.h 4 Aug 2003 00:43:29 -0000 1.5 +++ src/include/pg_config_manual.h 27 Aug 2003 17:40:12 -0000 @@ -23,7 +23,7 @@ * * Changing BLCKSZ requires an initdb. */ -#define BLCKSZ 8192 +#define BLCKSZ 16384 /* * RELSEG_SIZE is the maximum number of blocks allowed in one disk
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