From 3862529a39ee63f7493aa6c53f5739720cdbb6a1 Mon Sep 17 00:00:00 2001
From: Robey Pointer <robey@twitter.com>
Date: Thu, 19 Aug 2010 16:47:07 -0700
Subject: [PATCH] add memory_pressure_selection config.

---
 src/config.c | 2 ++
 src/redis.c  | 3 ++-
 src/redis.h  | 1 +
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/config.c b/src/config.c
index 7dd84e810..329d2ce84 100644
--- a/src/config.c
+++ b/src/config.c
@@ -123,6 +123,8 @@ void loadServerConfig(char *filename) {
             server.maxclients = atoi(argv[1]);
         } else if (!strcasecmp(argv[0],"maxmemory") && argc == 2) {
             server.maxmemory = memtoll(argv[1],NULL);
+        } else if (!strcasecmp(argv[0],"memory_pressure_selection") && argc == 2) {
+            server.memory_pressure_selection = atoi(argv[1]);
         } else if (!strcasecmp(argv[0],"slaveof") && argc == 3) {
             server.masterhost = sdsnew(argv[1]);
             server.masterport = atoi(argv[2]);
diff --git a/src/redis.c b/src/redis.c
index 37c8717e1..604c59e35 100644
--- a/src/redis.c
+++ b/src/redis.c
@@ -733,6 +733,7 @@ void initServerConfig() {
     server.maxclients = 0;
     server.blpop_blocked_clients = 0;
     server.maxmemory = 0;
+    server.memory_pressure_selection = 3;
     server.vm_enabled = 0;
     server.vm_swap_file = zstrdup("/tmp/redis-%p.vm");
     server.vm_page_size = 256;          /* 256 bytes per page */
@@ -1328,7 +1329,7 @@ void freeMemoryIfNeeded(void) {
                 freed = 1;
                 /* From a sample of three keys drop the one nearest to
                  * the natural expire */
-                for (k = 0; k < 3; k++) {
+                for (k = 0; k < server.memory_pressure_selection; k++) {
                     time_t t;
 
                     de = dictGetRandomKey(server.db[j].expires);
diff --git a/src/redis.h b/src/redis.h
index e52688a95..13326d02a 100644
--- a/src/redis.h
+++ b/src/redis.h
@@ -381,6 +381,7 @@ struct redisServer {
     int replstate;
     unsigned int maxclients;
     unsigned long long maxmemory;
+    int memory_pressure_selection; /* # of candidates to choose from in freeMemoryIfNeeded(). */
     unsigned int blpop_blocked_clients;
     unsigned int vm_blocked_clients;
     /* Sort parameters - qsort_r() is only available under BSD so we
-- 
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