Begin purging dirty pages from the cache once 90% of the cache is dirty (insteadof waiting until it is 100% dirty). This improves performance in some circumstances by effectively reserving 10% of the configured page-cache for frequently reused read-only pages. (CVS 6341)

FossilOrigin-Name: 823fe7f5551e121e211d1ede606a7ce7487ffe0d

manifest

@@ -1,5 +1,5 @@
-C Comment\sout\sa\srecently\sadded\sassert\sstatement\sthat\sis\sfailing.\s(CVS\s6340)
-D 2009-03-05T14:53:18
+C Begin\spurging\sdirty\spages\sfrom\sthe\scache\sonce\s90%\sof\sthe\scache\sis\sdirty\s(insteadof\swaiting\suntil\sit\sis\s100%\sdirty).\sThis\simproves\sperformance\sin\ssome\scircumstances\sby\seffectively\sreserving\s10%\sof\sthe\sconfigured\spage-cache\sfor\sfrequently\sreused\sread-only\spages.\s(CVS\s6341)
+D 2009-03-05T14:59:40
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in d64baddbf55cdf33ff030e14da837324711a4ef7
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -147,7 +147,7 @@ F src/pager.h 0c9f3520c00d8a3b8e792ca56c9a11b6b02b4b0f
 F src/parse.y c315b6f9bf6c7e7ec985481f81b6a45dba6c26d0
 F src/pcache.c fcf7738c83c4d3e9d45836b2334c8a368cc41274
 F src/pcache.h 9b927ccc5a538e31b4c3bc7eec4f976db42a1324
-F src/pcache1.c dabb8ab14827e090321f17150ce96fda172974e8
+F src/pcache1.c f12518540ba776df3051215c4244e9cdc06b09cd
 F src/pragma.c 22ed04836aab8ce134c53be1ca896f3ad20fabdb
 F src/prepare.c 1a2d40c0c5fb9f244cf5e3aacc33abcc1e7b095a
 F src/printf.c 9866a9a9c4a90f6d4147407f373df3fd5d5f9b6f
@@ -485,7 +485,7 @@ F test/pager2.test d4b7f6b70ff018b9995e622a32526b275f515042
 F test/pager3.test 2323bf27fd5bd887b580247e5bce500ceee994b4
 F test/pageropt.test 3ee6578891baaca967f0bd349e4abfa736229e1a
 F test/pagesize.test 0d9ff3fedfce6e5ffe8fa7aca9b6d3433a2e843b
-F test/pcache.test ccd18b4d2b432f44319a82b0367ed843ee18cebd
+F test/pcache.test 70ad1d65cf73f6a0a7501e0236312eb214d93a55
 F test/pcache2.test 46efd980a89f737847b99327bda19e08fe11e402
 F test/permutations.test 2e777ae1eeb11b777b31aad929c4351464758441
 F test/pragma.test a35b0be36542477183168cdb8b743f5c0d883c4d
@@ -703,7 +703,7 @@ F tool/speedtest16.c c8a9c793df96db7e4933f0852abb7a03d48f2e81
 F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
-P 68abcb278ced40c0d97af724dbd1b751a3becdc2
-R 0b19691adcd1739892b0541fe5daf832
+P d0b2015f1caf2fc60ec82bd8e760f7b61befa3b4
+R 039bb14c767370b62d0edeb68de61ac0
 U danielk1977
-Z e314e181dfce2d061b5e2a985f7bf325
+Z 7a03629d714ccf300df7a819fca83b05

manifest.uuid

@@ -1 +1 @@
-d0b2015f1caf2fc60ec82bd8e760f7b61befa3b4
+823fe7f5551e121e211d1ede606a7ce7487ffe0d

src/pcache1.c

@@ -16,7 +16,7 @@
 ** If the default page cache implementation is overriden, then neither of
 ** these two features are available.
 **
-** @(#) $Id: pcache1.c,v 1.8 2009/01/23 16:45:01 danielk1977 Exp $
+** @(#) $Id: pcache1.c,v 1.9 2009/03/05 14:59:40 danielk1977 Exp $
 */
 
 #include "sqliteInt.h"
@@ -516,7 +516,7 @@ static void *pcache1Fetch(sqlite3_pcache *p, unsigned int iKey, int createFlag){
   nPinned = pCache->nPage - pCache->nRecyclable;
   if( createFlag==1 && pCache->bPurgeable && (
         nPinned>=(pcache1.nMaxPage+pCache->nMin-pcache1.nMinPage)
-     || nPinned>=(pCache->nMax)
+     || nPinned>=(pCache->nMax * 9 / 10)
   )){
     goto fetch_out;
   }

test/pcache.test

@@ -11,7 +11,7 @@
 #
 # This file is focused on testing the pcache module.
 #
-# $Id: pcache.test,v 1.3 2009/01/07 15:33:46 drh Exp $
+# $Id: pcache.test,v 1.4 2009/03/05 14:59:40 danielk1977 Exp $
 
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
@@ -30,11 +30,11 @@ do_test pcache-1.1 {
 do_test pcache-1.2 {
   sqlite3 db test.db
   execsql {
-    PRAGMA cache_size=10;
+    PRAGMA cache_size=12;
     PRAGMA auto_vacuum=0;
   }
   pcache_stats
-} {current 1 max 10 min 10 recyclable 1}
+} {current 1 max 12 min 10 recyclable 1}
 
 do_test pcache-1.3 {
   execsql {
@@ -46,7 +46,7 @@ do_test pcache-1.3 {
     CREATE TABLE t5(a, b, c);
   }
   pcache_stats
-} {current 6 max 10 min 10 recyclable 0}
+} {current 6 max 12 min 10 recyclable 0}
 
 do_test pcache-1.4 {
   execsql {
@@ -56,13 +56,13 @@ do_test pcache-1.4 {
     CREATE TABLE t9(a, b, c);
   }
   pcache_stats
-} {current 10 max 10 min 10 recyclable 0}
+} {current 10 max 12 min 10 recyclable 0}
 
 do_test pcache-1.5 {
   sqlite3 db2 test.db
   execsql "PRAGMA cache_size=10" db2
   pcache_stats
-} {current 11 max 20 min 20 recyclable 1}
+} {current 11 max 22 min 20 recyclable 1}
 
 do_test pcache-1.6.1 {
   execsql {
@@ -70,7 +70,7 @@ do_test pcache-1.6.1 {
     SELECT * FROM sqlite_master;
   } db2
   pcache_stats
-} {current 11 max 20 min 20 recyclable 0}
+} {current 11 max 22 min 20 recyclable 0}
 
 # At this point connection db2 has a read lock on the database file and a 
 # single pinned page in its cache. Connection [db] is holding 10 dirty 
@@ -87,16 +87,18 @@ do_test pcache-1.6.2 {
     CREATE INDEX i7 ON t7(a, b);
     CREATE INDEX i8 ON t8(a, b);
     CREATE INDEX i9 ON t9(a, b);
+    CREATE INDEX i10 ON t9(a, b);
+    CREATE INDEX i11 ON t9(a, b);
   } 
   pcache_stats
-} {current 20 max 20 min 20 recyclable 0}
+} {current 23 max 22 min 20 recyclable 0}
 
 do_test pcache-1.7 {
   execsql {
     CREATE TABLE t10(a, b, c);
   } 
   pcache_stats
-} {current 21 max 20 min 20 recyclable 0}
+} {current 24 max 22 min 20 recyclable 0}
 
 # Rolling back the transaction held by db2 at this point releases a pinned
 # page. Because the number of allocated pages is greater than the 
@@ -106,22 +108,22 @@ do_test pcache-1.7 {
 do_test pcache-1.8 {
   execsql {ROLLBACK} db2
   pcache_stats
-} {current 20 max 20 min 20 recyclable 0}
+} {current 23 max 22 min 20 recyclable 0}
 
 do_test pcache-1.9 {
   execsql COMMIT
   pcache_stats
-} {current 20 max 20 min 20 recyclable 20}
+} {current 22 max 22 min 20 recyclable 22}
 
 do_test pcache-1.10 {
   db2 close
   pcache_stats
-} {current 10 max 10 min 10 recyclable 10}
+} {current 12 max 12 min 10 recyclable 12}
 
 do_test pcache-1.11 {
   execsql { PRAGMA cache_size = 20 }
   pcache_stats
-} {current 10 max 20 min 10 recyclable 10}
+} {current 12 max 20 min 10 recyclable 12}
 
 do_test pcache-1.12 {
   execsql {