From 39e784abd240bf622d3a794e43c4ee5f8659dd9f Mon Sep 17 00:00:00 2001
From: Patrick LeBlanc <patrick.leblanc@mariadb.com>
Date: Mon, 19 Nov 2018 14:32:14 -0600
Subject: [PATCH] MCOL-1847.  Added a config param for PM cache size.

New param is 'NumBlocksInMB', which will be the size
of the block cache in MB.
---
 oam/etc/Columnstore.xml              |  5 +++++
 oam/etc/Columnstore.xml.singleserver |  7 ++++++-
 primitives/primproc/primproc.cpp     | 27 +++++++++++++++++++++------
 3 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/oam/etc/Columnstore.xml b/oam/etc/Columnstore.xml
index 6ffd1efe7..79fb0cff5 100644
--- a/oam/etc/Columnstore.xml
+++ b/oam/etc/Columnstore.xml
@@ -428,6 +428,11 @@
 	<DBBC>
 		<!-- The percentage of RAM to use for the disk block cache. Defaults to 70% -->
 		<!-- <NumBlocksPct>70</NumBlocksPct> -->
+
+        <!-- If preferred, the user can specify cache size in terms of megabytes.
+             If both Pct and MB are specified, PrimProc will use Pct. -->
+        <!-- <NumBlocksInMB>2048</NumBlocksInMB> -->
+
 		<!-- <NumThreads>16</NumThreads> --> <!-- 1-256.  Default is 16. -->
 		<NumCaches>1</NumCaches><!-- # of parallel caches to instantiate -->
 		<IOMTracing>0</IOMTracing>
diff --git a/oam/etc/Columnstore.xml.singleserver b/oam/etc/Columnstore.xml.singleserver
index 2ed98d87f..75e741ada 100644
--- a/oam/etc/Columnstore.xml.singleserver
+++ b/oam/etc/Columnstore.xml.singleserver
@@ -418,8 +418,13 @@
 		<Module>unassigned</Module>
 	</DBRM_Worker10>
 	<DBBC>
-		<!-- The percentage of RAM to use for the disk block cache. Defaults to 86% -->
+		<!-- The percentage of RAM to use for the disk block cache. Defaults to 70% -->
 		<NumBlocksPct>50</NumBlocksPct>
+
+        <!-- If preferred, the user can specify cache size in terms of megabytes.
+             If both Pct and MB are specified, PrimProc will use Pct. -->
+        <!-- <NumBlocksInMB>2048</NumBlocksInMB> -->
+
 		<!-- <NumThreads>16</NumThreads> --> <!-- 1-256.  Default is 16. -->
 		<NumCaches>1</NumCaches><!-- # of parallel caches to instantiate -->
 		<IOMTracing>0</IOMTracing>
diff --git a/primitives/primproc/primproc.cpp b/primitives/primproc/primproc.cpp
index 0ff38f0de..17a3b027f 100644
--- a/primitives/primproc/primproc.cpp
+++ b/primitives/primproc/primproc.cpp
@@ -503,12 +503,19 @@ int main(int argc, char* argv[])
     }
 
     string strBlockPct = cf->getConfig(dbbc, "NumBlocksPct");
-    temp = atoi(strBlockPct.c_str());
+    string strBlockAbs = cf->getConfig(dbbc, "NumBlocksInMB");
+    bool usePct = !(strBlockPct.empty());   // which to use.  Prefer Pct if both are specified.
 
+    if (usePct)
+        temp = atoi(strBlockPct.c_str());
+    else
+        temp = atoi(strBlockAbs.c_str());
+
+#ifdef _MSC_VER
+    /* TODO: implement handling for NumBlocksInMB */
     if (temp > 0)
         BRPBlocksPct = temp;
 
-#ifdef _MSC_VER
     MEMORYSTATUSEX memStat;
     memStat.dwLength = sizeof(memStat);
 
@@ -525,10 +532,18 @@ int main(int argc, char* argv[])
     }
 
 #else
-    // _SC_PHYS_PAGES is in 4KB units. Dividing by 200 converts to 8KB and gets ready to work in pct
-    // _SC_PHYS_PAGES should always be >> 200 so we shouldn't see a total loss of precision
-    //BRPBlocks = sysconf(_SC_PHYS_PAGES) / 200 * BRPBlocksPct;
-    BRPBlocks = ((BRPBlocksPct / 100.0) * (double) cg.getTotalMemory()) / 8192;
+    if (usePct)
+    {
+        if (temp > 0)
+            BRPBlocksPct = temp;
+        BRPBlocks = ((BRPBlocksPct / 100.0) * (double) cg.getTotalMemory()) / 8192;
+    }
+    else
+    {
+        if (temp > 0)
+            BRPBlocks = temp * 128;   // 128 blocks per MB.
+        else
+            BRPBlocks = 131072;   // 1GB, why not.
 #endif
 #if 0
     temp = toInt(cf->getConfig(dbbc, "NumThreads"));