[Xen-devel] [RFC PATCH 1/4] tmem: infrastructure for tmem layer

[Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>]

--- linux-2.6.30/mm/Kconfig     2009-06-09 21:05:27.000000000 -0600
+++ linux-2.6.30-tmem/mm/Kconfig        2009-06-19 09:36:41.000000000 -0600
@@ -253,3 +253,30 @@
          of 1 says that all excess pages should be trimmed.
 
          See Documentation/nommu-mmap.txt for more information.
+
+#
+# support for transcendent memory
+#
+config TMEM
+       bool "Transcendent memory support"
+       depends on XEN # but in future may work without XEN
+       help
+         In a virtualized environment, allows unused and underutilized
+         system physical memory to be made accessible through a narrow
+         well-defined page-copy-based API.  If unsure, say Y.
+
+config PRECACHE
+       bool "Cache clean pages in transcendent memory"
+       depends on TMEM
+       help
+         Allows the transcendent memory pool to be used to store clean
+         page-cache pages which, under some circumstances, will greatly
+         reduce paging and thus improve performance.  If unsure, say Y.
+
+config PRESWAP
+       bool "Swap pages to transcendent memory"
+       depends on TMEM
+       help
+         Allows the transcendent memory pool to be used as a pseudo-swap
+         device which, under some circumstances, will greatly reduce
+         swapping and thus improve performance.  If unsure, say Y.
--- linux-2.6.30/mm/Makefile    2009-06-09 21:05:27.000000000 -0600
+++ linux-2.6.30-tmem/mm/Makefile       2009-06-19 09:33:59.000000000 -0600
@@ -16,6 +16,8 @@
 obj-$(CONFIG_PROC_PAGE_MONITOR) += pagewalk.o
 obj-$(CONFIG_BOUNCE)   += bounce.o
 obj-$(CONFIG_SWAP)     += page_io.o swap_state.o swapfile.o thrash.o
+obj-$(CONFIG_PRESWAP)  += preswap.o
+obj-$(CONFIG_PRECACHE) += precache.o
 obj-$(CONFIG_HAS_DMA)  += dmapool.o
 obj-$(CONFIG_HUGETLBFS)        += hugetlb.o
 obj-$(CONFIG_NUMA)     += mempolicy.o
--- linux-2.6.30/include/linux/tmem.h   1969-12-31 17:00:00.000000000 -0700
+++ linux-2.6.30-tmem/include/linux/tmem.h      2009-06-19 11:21:58.000000000 
-0600
@@ -0,0 +1,22 @@
+/*
+ * linux/tmem.h
+ *
+ * Interface to transcendent memory, used by mm/precache.c and mm/preswap.c
+ *
+ * Copyright (C) 2008,2009 Dan Magenheimer, Oracle Corp.
+ */
+
+struct tmem_ops {
+       int (*new_pool)(u64 uuid_lo, u64 uuid_hi, u32 flags);
+       int (*put_page)(u32 pool_id, u64 object, u32 index, unsigned long gmfn);
+       int (*get_page)(u32 pool_id, u64 object, u32 index, unsigned long gmfn);
+       int (*flush_page)(u32 pool_id, u64 object, u32 index);
+       int (*flush_object)(u32 pool_id, u64 object);
+       int (*destroy_pool)(u32 pool_id);
+};
+
+extern struct tmem_ops *tmem_ops;
+
+/* flags for tmem_ops.new_pool */
+#define TMEM_POOL_PERSIST          1
+#define TMEM_POOL_SHARED           2

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