xen: cleancache shim to Xen Transcendent Memory
This patch provides a shim between the kernel-internal cleancache
API (see Documentation/mm/cleancache.txt) and the Xen Transcendent
Memory ABI (see http://oss.oracle.com/projects/tmem).
Xen tmem provides "hypervisor RAM" as an ephemeral page-oriented
pseudo-RAM store for cleancache pages, shared cleancache pages,
and frontswap pages. Tmem provides enterprise-quality concurrency,
full save/restore and live migration support, compression
and deduplication.
A presentation showing up to 8% faster performance and up to 52%
reduction in sectors read on a kernel compile workload, despite
aggressive in-kernel page reclamation ("self-ballooning") can be
found at:
http://oss.oracle.com/projects/tmem/dist/documentation/presentations/TranscendentMemoryXenSummit2010.pdf
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Rik Van Riel <riel@redhat.com>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Andreas Dilger <adilger@sun.com>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Nitin Gupta <ngupta@vflare.org>
diff --git a/include/xen/interface/xen.h b/include/xen/interface/xen.h
index b33257b..70213b4 100644
--- a/include/xen/interface/xen.h
+++ b/include/xen/interface/xen.h
@@ -58,6 +58,7 @@
#define __HYPERVISOR_event_channel_op 32
#define __HYPERVISOR_physdev_op 33
#define __HYPERVISOR_hvm_op 34
+#define __HYPERVISOR_tmem_op 38
/* Architecture-specific hypercall definitions. */
#define __HYPERVISOR_arch_0 48
@@ -461,6 +462,27 @@
#define __mk_unsigned_long(x) x ## UL
#define mk_unsigned_long(x) __mk_unsigned_long(x)
+#define TMEM_SPEC_VERSION 1
+
+struct tmem_op {
+ uint32_t cmd;
+ int32_t pool_id;
+ union {
+ struct { /* for cmd == TMEM_NEW_POOL */
+ uint64_t uuid[2];
+ uint32_t flags;
+ } new;
+ struct {
+ uint64_t oid[3];
+ uint32_t index;
+ uint32_t tmem_offset;
+ uint32_t pfn_offset;
+ uint32_t len;
+ GUEST_HANDLE(void) gmfn; /* guest machine page frame */
+ } gen;
+ } u;
+};
+
#else /* __ASSEMBLY__ */
/* In assembly code we cannot use C numeric constant suffixes. */