xen: cleancache shim to Xen Transcendent Memory
Dan Magenheimer [Thu, 26 May 2011 16:02:21 +0000 (10:02 -0600)]
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>

arch/x86/include/asm/xen/hypercall.h
drivers/xen/Makefile
drivers/xen/tmem.c [new file with mode: 0644]
include/xen/interface/xen.h

index 8508bfe..d240ea9 100644 (file)
@@ -447,6 +447,13 @@ HYPERVISOR_hvm_op(int op, void *arg)
        return _hypercall2(unsigned long, hvm_op, op, arg);
 }
 
+static inline int
+HYPERVISOR_tmem_op(
+       struct tmem_op *op)
+{
+       return _hypercall1(int, tmem_op, op);
+}
+
 static inline void
 MULTI_fpu_taskswitch(struct multicall_entry *mcl, int set)
 {
index f420f1f..7aa6804 100644 (file)
@@ -1,5 +1,6 @@
 obj-y  += grant-table.o features.o events.o manage.o balloon.o
 obj-y  += xenbus/
+obj-y  += tmem.o
 
 nostackp := $(call cc-option, -fno-stack-protector)
 CFLAGS_features.o                      := $(nostackp)
diff --git a/drivers/xen/tmem.c b/drivers/xen/tmem.c
new file mode 100644 (file)
index 0000000..816a449
--- /dev/null
@@ -0,0 +1,264 @@
+/*
+ * Xen implementation for transcendent memory (tmem)
+ *
+ * Copyright (C) 2009-2010 Oracle Corp.  All rights reserved.
+ * Author: Dan Magenheimer
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/pagemap.h>
+#include <linux/cleancache.h>
+
+#include <xen/xen.h>
+#include <xen/interface/xen.h>
+#include <asm/xen/hypercall.h>
+#include <asm/xen/page.h>
+#include <asm/xen/hypervisor.h>
+
+#define TMEM_CONTROL               0
+#define TMEM_NEW_POOL              1
+#define TMEM_DESTROY_POOL          2
+#define TMEM_NEW_PAGE              3
+#define TMEM_PUT_PAGE              4
+#define TMEM_GET_PAGE              5
+#define TMEM_FLUSH_PAGE            6
+#define TMEM_FLUSH_OBJECT          7
+#define TMEM_READ                  8
+#define TMEM_WRITE                 9
+#define TMEM_XCHG                 10
+
+/* Bits for HYPERVISOR_tmem_op(TMEM_NEW_POOL) */
+#define TMEM_POOL_PERSIST          1
+#define TMEM_POOL_SHARED           2
+#define TMEM_POOL_PAGESIZE_SHIFT   4
+#define TMEM_VERSION_SHIFT        24
+
+
+struct tmem_pool_uuid {
+       u64 uuid_lo;
+       u64 uuid_hi;
+};
+
+struct tmem_oid {
+       u64 oid[3];
+};
+
+#define TMEM_POOL_PRIVATE_UUID { 0, 0 }
+
+/* flags for tmem_ops.new_pool */
+#define TMEM_POOL_PERSIST          1
+#define TMEM_POOL_SHARED           2
+
+/* xen tmem foundation ops/hypercalls */
+
+static inline int xen_tmem_op(u32 tmem_cmd, u32 tmem_pool, struct tmem_oid oid,
+       u32 index, unsigned long gmfn, u32 tmem_offset, u32 pfn_offset, u32 len)
+{
+       struct tmem_op op;
+       int rc = 0;
+
+       op.cmd = tmem_cmd;
+       op.pool_id = tmem_pool;
+       op.u.gen.oid[0] = oid.oid[0];
+       op.u.gen.oid[1] = oid.oid[1];
+       op.u.gen.oid[2] = oid.oid[2];
+       op.u.gen.index = index;
+       op.u.gen.tmem_offset = tmem_offset;
+       op.u.gen.pfn_offset = pfn_offset;
+       op.u.gen.len = len;
+       set_xen_guest_handle(op.u.gen.gmfn, (void *)gmfn);
+       rc = HYPERVISOR_tmem_op(&op);
+       return rc;
+}
+
+static int xen_tmem_new_pool(struct tmem_pool_uuid uuid,
+                               u32 flags, unsigned long pagesize)
+{
+       struct tmem_op op;
+       int rc = 0, pageshift;
+
+       for (pageshift = 0; pagesize != 1; pageshift++)
+               pagesize >>= 1;
+       flags |= (pageshift - 12) << TMEM_POOL_PAGESIZE_SHIFT;
+       flags |= TMEM_SPEC_VERSION << TMEM_VERSION_SHIFT;
+       op.cmd = TMEM_NEW_POOL;
+       op.u.new.uuid[0] = uuid.uuid_lo;
+       op.u.new.uuid[1] = uuid.uuid_hi;
+       op.u.new.flags = flags;
+       rc = HYPERVISOR_tmem_op(&op);
+       return rc;
+}
+
+/* xen generic tmem ops */
+
+static int xen_tmem_put_page(u32 pool_id, struct tmem_oid oid,
+                            u32 index, unsigned long pfn)
+{
+       unsigned long gmfn = xen_pv_domain() ? pfn_to_mfn(pfn) : pfn;
+
+       return xen_tmem_op(TMEM_PUT_PAGE, pool_id, oid, index,
+               gmfn, 0, 0, 0);
+}
+
+static int xen_tmem_get_page(u32 pool_id, struct tmem_oid oid,
+                            u32 index, unsigned long pfn)
+{
+       unsigned long gmfn = xen_pv_domain() ? pfn_to_mfn(pfn) : pfn;
+
+       return xen_tmem_op(TMEM_GET_PAGE, pool_id, oid, index,
+               gmfn, 0, 0, 0);
+}
+
+static int xen_tmem_flush_page(u32 pool_id, struct tmem_oid oid, u32 index)
+{
+       return xen_tmem_op(TMEM_FLUSH_PAGE, pool_id, oid, index,
+               0, 0, 0, 0);
+}
+
+static int xen_tmem_flush_object(u32 pool_id, struct tmem_oid oid)
+{
+       return xen_tmem_op(TMEM_FLUSH_OBJECT, pool_id, oid, 0, 0, 0, 0, 0);
+}
+
+static int xen_tmem_destroy_pool(u32 pool_id)
+{
+       struct tmem_oid oid = { { 0 } };
+
+       return xen_tmem_op(TMEM_DESTROY_POOL, pool_id, oid, 0, 0, 0, 0, 0);
+}
+
+int tmem_enabled;
+
+static int __init enable_tmem(char *s)
+{
+       tmem_enabled = 1;
+       return 1;
+}
+
+__setup("tmem", enable_tmem);
+
+/* cleancache ops */
+
+static void tmem_cleancache_put_page(int pool, struct cleancache_filekey key,
+                                    pgoff_t index, struct page *page)
+{
+       u32 ind = (u32) index;
+       struct tmem_oid oid = *(struct tmem_oid *)&key;
+       unsigned long pfn = page_to_pfn(page);
+
+       if (pool < 0)
+               return;
+       if (ind != index)
+               return;
+       mb(); /* ensure page is quiescent; tmem may address it with an alias */
+       (void)xen_tmem_put_page((u32)pool, oid, ind, pfn);
+}
+
+static int tmem_cleancache_get_page(int pool, struct cleancache_filekey key,
+                                   pgoff_t index, struct page *page)
+{
+       u32 ind = (u32) index;
+       struct tmem_oid oid = *(struct tmem_oid *)&key;
+       unsigned long pfn = page_to_pfn(page);
+       int ret;
+
+       /* translate return values to linux semantics */
+       if (pool < 0)
+               return -1;
+       if (ind != index)
+               return -1;
+       ret = xen_tmem_get_page((u32)pool, oid, ind, pfn);
+       if (ret == 1)
+               return 0;
+       else
+               return -1;
+}
+
+static void tmem_cleancache_flush_page(int pool, struct cleancache_filekey key,
+                                      pgoff_t index)
+{
+       u32 ind = (u32) index;
+       struct tmem_oid oid = *(struct tmem_oid *)&key;
+
+       if (pool < 0)
+               return;
+       if (ind != index)
+               return;
+       (void)xen_tmem_flush_page((u32)pool, oid, ind);
+}
+
+static void tmem_cleancache_flush_inode(int pool, struct cleancache_filekey key)
+{
+       struct tmem_oid oid = *(struct tmem_oid *)&key;
+
+       if (pool < 0)
+               return;
+       (void)xen_tmem_flush_object((u32)pool, oid);
+}
+
+static void tmem_cleancache_flush_fs(int pool)
+{
+       if (pool < 0)
+               return;
+       (void)xen_tmem_destroy_pool((u32)pool);
+}
+
+static int tmem_cleancache_init_fs(size_t pagesize)
+{
+       struct tmem_pool_uuid uuid_private = TMEM_POOL_PRIVATE_UUID;
+
+       return xen_tmem_new_pool(uuid_private, 0, pagesize);
+}
+
+static int tmem_cleancache_init_shared_fs(char *uuid, size_t pagesize)
+{
+       struct tmem_pool_uuid shared_uuid;
+
+       shared_uuid.uuid_lo = *(u64 *)uuid;
+       shared_uuid.uuid_hi = *(u64 *)(&uuid[8]);
+       return xen_tmem_new_pool(shared_uuid, TMEM_POOL_SHARED, pagesize);
+}
+
+static int use_cleancache = 1;
+
+static int __init no_cleancache(char *s)
+{
+       use_cleancache = 0;
+       return 1;
+}
+
+__setup("nocleancache", no_cleancache);
+
+static struct cleancache_ops tmem_cleancache_ops = {
+       .put_page = tmem_cleancache_put_page,
+       .get_page = tmem_cleancache_get_page,
+       .flush_page = tmem_cleancache_flush_page,
+       .flush_inode = tmem_cleancache_flush_inode,
+       .flush_fs = tmem_cleancache_flush_fs,
+       .init_shared_fs = tmem_cleancache_init_shared_fs,
+       .init_fs = tmem_cleancache_init_fs
+};
+
+static int __init xen_tmem_init(void)
+{
+       struct cleancache_ops old_ops;
+
+       if (!xen_domain())
+               return 0;
+#ifdef CONFIG_CLEANCACHE
+       BUG_ON(sizeof(struct cleancache_filekey) != sizeof(struct tmem_oid));
+       if (tmem_enabled && use_cleancache) {
+               char *s = "";
+               old_ops = cleancache_register_ops(&tmem_cleancache_ops);
+               if (old_ops.init_fs != NULL)
+                       s = " (WARNING: cleancache_ops overridden)";
+               printk(KERN_INFO "cleancache enabled, RAM provided by "
+                                "Xen Transcendent Memory%s\n", s);
+       }
+#endif
+       return 0;
+}
+
+module_init(xen_tmem_init)
index b33257b..70213b4 100644 (file)
@@ -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 @@ typedef uint8_t xen_domain_handle_t[16];
 #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. */