From 0fb68ef1f8c7f44c6f7edc1cc461d2b598b96fd9 Mon Sep 17 00:00:00 2001
From: Sverker Eriksson <sverker@erlang.org>
Date: Tue, 4 Dec 2012 17:57:51 +0100
Subject: erts: Set super alignment (256kb) and limits for sbct (8Mb) and lmbcs
 (128Mb)

---
 erts/doc/src/erts_alloc.xml         | 6 ++++--
 erts/emulator/beam/erl_alloc_util.h | 3 ++-
 erts/emulator/sys/common/erl_mseg.h | 3 ++-
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/erts/doc/src/erts_alloc.xml b/erts/doc/src/erts_alloc.xml
index ec5e7d9b74..87d6682328 100644
--- a/erts/doc/src/erts_alloc.xml
+++ b/erts/doc/src/erts_alloc.xml
@@ -341,7 +341,8 @@
        Largest (<c>mseg_alloc</c>) multiblock carrier size (in
        kilobytes).  See <seealso marker="#mseg_mbc_sizes">the description
        on how sizes for mseg_alloc multiblock carriers are decided</seealso>
-       in "the <c>alloc_util</c> framework" section.</item>
+       in "the <c>alloc_util</c> framework" section. On 32-bit Unix style OS
+       this limit can not be set higher than 128 megabyte.</item>
       <tag><marker id="M_mbcgs"><c><![CDATA[+M<S>mbcgs <ratio>]]></c></marker></tag>
       <item>
        (<c>mseg_alloc</c>) multiblock carrier growth stages. See
@@ -413,7 +414,8 @@
        Singleblock carrier threshold. Blocks larger than this
        threshold will be placed in singleblock carriers. Blocks
        smaller than this threshold will be placed in multiblock
-       carriers.</item>
+       carriers. On 32-bit Unix style OS this threshold can not be set higher
+       than 8 megabytes.</item>
       <tag><marker id="M_sbmbcs"><c><![CDATA[+M<S>sbmbcs <size>]]></c></marker></tag>
       <item>
 	Small block multiblock carrier size (in bytes). Memory blocks smaller
diff --git a/erts/emulator/beam/erl_alloc_util.h b/erts/emulator/beam/erl_alloc_util.h
index 423bb0517e..e0754e7f69 100644
--- a/erts/emulator/beam/erl_alloc_util.h
+++ b/erts/emulator/beam/erl_alloc_util.h
@@ -226,7 +226,8 @@ erts_aint32_t erts_alcu_fix_alloc_shrink(Allctr_t *, erts_aint32_t);
 #  ifdef ARCH_64 
 #    define MBC_ABLK_OFFSET_BITS   24
 #  elif HAVE_SUPER_ALIGNED_MB_CARRIERS
-#    define MBC_ABLK_OFFSET_BITS   13
+#    define MBC_ABLK_OFFSET_BITS   9
+     /* Affects hard limits for sbct and lmbcs documented in erts_alloc.xml */
 #  endif
 #endif
 #ifndef MBC_ABLK_OFFSET_BITS
diff --git a/erts/emulator/sys/common/erl_mseg.h b/erts/emulator/sys/common/erl_mseg.h
index 8f8cb0e121..6f373f13f9 100644
--- a/erts/emulator/sys/common/erl_mseg.h
+++ b/erts/emulator/sys/common/erl_mseg.h
@@ -39,7 +39,8 @@
 #endif
 
 #if HAVE_SUPER_ALIGNED_MB_CARRIERS
-#  define MSEG_ALIGN_BITS       (17)
+#  define MSEG_ALIGN_BITS (18)
+   /* Affects hard limits for sbct and lmbcs documented in erts_alloc.xml */
 #else
 /* If we don't use super aligned multiblock carriers
  * we will mmap with page size alignment (and thus use corresponding
-- 
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