linux/drivers/xen/tmem.c
Dan Magenheimer 5bc20fc597 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>
2011-05-26 10:02:21 -06:00

264 lines
6.3 KiB
C

/*
* 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)