From: Cédric Villemain <cedric@2ndquadrant.fr>
Date: Sun, 1 May 2011 20:44:29 +0000 (+0200)
Subject: Add an extension to calculate OSCache
X-Git-Url: http://git.postgresql.org/gitweb/static/main.js?a=commitdiff_plain;h=40cefa392974c73ec20deb3c15fb5111ed7fad17;p=users%2Fc2main%2Fpostgres.git

Add an extension to calculate OSCache
---

diff --git a/contrib/Makefile b/contrib/Makefile
index 696776795e..47652d536b 100644
--- a/contrib/Makefile
+++ b/contrib/Makefile
@@ -27,6 +27,7 @@ SUBDIRS = \
 		lo		\
 		ltree		\
 		oid2name	\
+		oscache	\
 		pageinspect	\
 		passwordcheck	\
 		pg_archivecleanup \
diff --git a/contrib/oscache/Makefile b/contrib/oscache/Makefile
new file mode 100644
index 0000000000..8d8dcc5dd4
--- /dev/null
+++ b/contrib/oscache/Makefile
@@ -0,0 +1,15 @@
+# contrib/oscache/Makefile
+
+MODULE_big = oscache
+OBJS = oscache.o
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = contrib/oscache
+top_builddir = ../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
diff --git a/contrib/oscache/oscache.c b/contrib/oscache/oscache.c
new file mode 100644
index 0000000000..1ad7dc23b6
--- /dev/null
+++ b/contrib/oscache/oscache.c
@@ -0,0 +1,151 @@
+/*-------------------------------------------------------------------------
+ *
+ * oscache.c
+ *
+ *
+ * Copyright (c) 2011, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/oscache/oscache.c
+ *
+ *-------------------------------------------------------------------------
+ */
+/* { POSIX stuff */
+#include <stdlib.h> /* exit, calloc, free */
+#include <sys/stat.h> /* stat, fstat */
+#include <sys/types.h> /* size_t, mincore */
+#include <unistd.h> /* sysconf, close */
+#include <sys/mman.h> /* mmap, mincore */
+/* } */
+
+/* { PostgreSQL stuff */
+#include "postgres.h" /* general Postgres declarations */
+#include "utils/rel.h" /* Relation */
+#include "storage/bufmgr.h"
+#include "catalog/catalog.h" /* relpath */
+/* } */
+
+PG_MODULE_MAGIC;
+
+void		_PG_init(void);
+
+float4 oscache(Relation, ForkNumber);
+
+/*
+ * Module load callback
+ */
+void
+_PG_init(void)
+{
+	/* Install hook. */
+	OSCache_hook = &oscache;
+}
+
+/*
+ * oscache process the os cache inspection for the relation.
+ * It returns the percentage of blocks in OS cache.
+ */
+float4
+oscache(Relation relation, ForkNumber forkNum)
+{
+	int  segment = 0;
+	char *relationpath;
+	char filename[MAXPGPATH];
+	int fd;
+	int64  total_block_disk = 0;
+	int64  total_block_mem  = 0;
+
+	/* OS things */
+	int64 pageSize  = sysconf(_SC_PAGESIZE); /* Page size */
+	register int64 pageIndex;
+
+	relationpath = relpathperm(relation->rd_node, forkNum);
+
+	/*
+	 * For each segment of the relation
+	 */
+	snprintf(filename, MAXPGPATH, "%s", relationpath);
+	while ((fd = open(filename, O_RDONLY)) != -1)
+	{
+		// for stat file
+		struct stat st;
+		// for mmap file
+		void *pa = (char *)0;
+		// for calloc file
+		unsigned char *vec = (unsigned char *)0;
+		int64  block_disk = 0;
+		int64  block_mem  = 0;
+
+		if (fstat(fd, &st) == -1)
+		{
+			close(fd);
+			elog(ERROR, "Can not stat object file : %s",
+				filename);
+			return 0;
+		}
+
+		/*
+		* if file ok
+		* then process
+		*/
+		if (st.st_size != 0)
+		{
+			/* number of block in the current file */
+			block_disk = st.st_size/pageSize;
+
+			/* TODO We need to split mmap size to be sure (?) to be able to mmap */
+			pa = mmap(NULL, st.st_size, PROT_NONE, MAP_SHARED, fd, 0);
+			if (pa == MAP_FAILED)
+			{
+				close(fd);
+				elog(ERROR, "Can not mmap object file : %s, errno = %i,%s\nThis error can happen if there is not enought space in memory to do the projection. Please mail cedric@2ndQuadrant.fr with '[oscache] ENOMEM' as subject.",
+					filename, errno, strerror(errno));
+				return 0;
+			}
+
+			/* Prepare our vector containing all blocks information */
+			vec = calloc(1, (st.st_size+pageSize-1)/pageSize);
+			if ((void *)0 == vec)
+			{
+				munmap(pa, st.st_size);
+				close(fd);
+				elog(ERROR, "Can not calloc object file : %s",
+					filename);
+				return 0;
+			}
+
+			/* Affect vec with mincore */
+			if (mincore(pa, st.st_size, vec) != 0)
+			{
+				free(vec);
+				munmap(pa, st.st_size);
+				close(fd);
+				elog(ERROR, "mincore(%p, %lld, %p): %s\n",
+					pa, (int64)st.st_size, vec, strerror(errno));
+				return 0;
+			}
+
+			/* handle the results */
+			for (pageIndex = 0; pageIndex <= st.st_size/pageSize; pageIndex++)
+			{
+				// block in memory
+				if (vec[pageIndex] & 1)
+				{
+					block_mem++;
+				}
+			}
+		}
+		elog(DEBUG1, "oscache %s: %lld of %lld block in linux cache",
+			filename, block_mem,  block_disk);
+
+		//   free things
+		free(vec);
+		munmap(pa, st.st_size);
+		close(fd);
+		total_block_mem += block_mem;
+		total_block_disk += block_disk;
+
+		snprintf(filename, MAXPGPATH, "%s.%u", relationpath, segment++);
+	}
+	return (float4)(total_block_mem*100/(total_block_disk+1));
+}