[experimental-ims] 8a37b31 Comment on struct sess size issues.

[Geoff Simmons]

commit 8a37b3122217fde89d98cc3b5ce0c9452ed843a1
Author: Poul-Henning Kamp <phk at FreeBSD.org>
Date:   Mon Jan 2 11:04:29 2012 +0000

    Comment on struct sess size issues.

diff --git a/bin/varnishd/cache/cache.h b/bin/varnishd/cache/cache.h
index 75bc803..6b0d0a9 100644
--- a/bin/varnishd/cache/cache.h
+++ b/bin/varnishd/cache/cache.h
@@ -624,7 +624,15 @@ struct req {
 
 };
 
-/*--------------------------------------------------------------------*/
+/*--------------------------------------------------------------------
+ * Struct sess is a high memory-load structure because sessions typically
+ * hang around the waiter for relatively long time.
+ *
+ * The size goal for struct sess + struct memitem is <512 bytes
+ *
+ * Getting down to the next relevant size (<256 bytes because of how malloc
+ * works, is not realistic without a lot of code changes.
+ */
 
 struct sess {
 	unsigned		magic;