[PATCH] Cleancache: shim to Xen Transcendent Memory This companion patch to the cleancache V3 patchset (see http://lkml.org/lkml/2010/6/21/411) provides one consumer for the proposed cleancache internal kernel API. This user is Xen Transcendent Memory ("tmem"), supported in Xen 4.0+. (A second user, zcache, will be posted by Nitin Gupta soon.) This patch affects Xen directories only; while broader review is welcome, the patch is provided primarily to answer concerns expressed about the apparent non-existence of consumers for the proposed cleancache patch. 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@xxxxxxxxxx> Diffstat: arch/x86/include/asm/xen/hypercall.h | 7 drivers/xen/Makefile | 2 drivers/xen/tmem.c | 238 +++++++++++++++++++++ include/xen/interface/xen.h | 20 + 4 files changed, 266 insertions(+), 1 deletion(-) diff -Napur linux-2.6.35-rc4/arch/x86/include/asm/xen/hypercall.h linux-2.6.35-rc4-cleancache_tmem/arch/x86/include/asm/xen/hypercall.h --- linux-2.6.35-rc4/arch/x86/include/asm/xen/hypercall.h 2010-07-04 21:22:50.000000000 -0600 +++ linux-2.6.35-rc4-cleancache_tmem/arch/x86/include/asm/xen/hypercall.h 2010-07-07 15:37:46.000000000 -0600 @@ -417,6 +417,13 @@ HYPERVISOR_nmi_op(unsigned long op, unsi return _hypercall2(int, nmi_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) { diff -Napur linux-2.6.35-rc4/drivers/xen/Makefile linux-2.6.35-rc4-cleancache_tmem/drivers/xen/Makefile --- linux-2.6.35-rc4/drivers/xen/Makefile 2010-07-04 21:22:50.000000000 -0600 +++ linux-2.6.35-rc4-cleancache_tmem/drivers/xen/Makefile 2010-07-07 09:38:21.000000000 -0600 @@ -1,5 +1,6 @@ obj-y += grant-table.o features.o events.o manage.o obj-y += xenbus/ +obj-y += tmem.o nostackp := $(call cc-option, -fno-stack-protector) CFLAGS_features.o := $(nostackp) @@ -9,4 +10,4 @@ obj-$(CONFIG_XEN_XENCOMM) += xencomm.o obj-$(CONFIG_XEN_BALLOON) += balloon.o obj-$(CONFIG_XEN_DEV_EVTCHN) += evtchn.o obj-$(CONFIG_XENFS) += xenfs/ -obj-$(CONFIG_XEN_SYS_HYPERVISOR) += sys-hypervisor.o \ No newline at end of file +obj-$(CONFIG_XEN_SYS_HYPERVISOR) += sys-hypervisor.o diff -Napur linux-2.6.35-rc4/drivers/xen/tmem.c linux-2.6.35-rc4-cleancache_tmem/drivers/xen/tmem.c --- linux-2.6.35-rc4/drivers/xen/tmem.c 1969-12-31 17:00:00.000000000 -0700 +++ linux-2.6.35-rc4-cleancache_tmem/drivers/xen/tmem.c 2010-07-07 16:24:08.000000000 -0600 @@ -0,0 +1,238 @@ +/* + * 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 + + +struct tmem_pool_uuid { + u64 uuid_lo; + u64 uuid_hi; +}; + +#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, u64 object, + 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.object = object; + 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; + 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, u64 object, 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, object, index, + gmfn, 0, 0, 0); +} + +static int xen_tmem_get_page(u32 pool_id, u64 object, 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, object, index, + gmfn, 0, 0, 0); +} + +static int xen_tmem_flush_page(u32 pool_id, u64 object, u32 index) +{ + return xen_tmem_op(TMEM_FLUSH_PAGE, pool_id, object, index, + 0, 0, 0, 0); +} + +static int xen_tmem_flush_object(u32 pool_id, u64 object) +{ + return xen_tmem_op(TMEM_FLUSH_OBJECT, pool_id, object, 0, 0, 0, 0, 0); +} + +static int xen_tmem_destroy_pool(u32 pool_id) +{ + return xen_tmem_op(TMEM_DESTROY_POOL, pool_id, 0, 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, ino_t inode, pgoff_t index, + struct page *page) +{ + u32 ind = (u32) index; + 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, (u64)inode, ind, pfn); +} + +static int tmem_cleancache_get_page(int pool, ino_t inode, pgoff_t index, + struct page *page) +{ + u32 ind = (u32) index; + 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, (u64)inode, ind, pfn); + if (ret == 1) + return 0; + else + return -1; +} + +static void tmem_cleancache_flush_page(int pool, ino_t inode, pgoff_t index) +{ + u32 ind = (u32) index; + + if (pool < 0) + return; + if (ind != index) + return; + (void)xen_tmem_flush_page((u32)pool, (u64)inode, ind); +} + +static void tmem_cleancache_flush_inode(int pool, ino_t inode) +{ + if (pool < 0) + return; + (void)xen_tmem_flush_object((u32)pool, (u64)inode); +} + +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 int __init xen_tmem_init(void) +{ + if (!xen_domain()) + return 0; +#ifdef CONFIG_CLEANCACHE + if (tmem_enabled && use_cleancache) { + cleancache_ops.put_page = tmem_cleancache_put_page; + cleancache_ops.get_page = tmem_cleancache_get_page; + cleancache_ops.flush_page = tmem_cleancache_flush_page; + cleancache_ops.flush_inode = tmem_cleancache_flush_inode; + cleancache_ops.flush_fs = tmem_cleancache_flush_fs; + cleancache_ops.init_shared_fs = tmem_cleancache_init_shared_fs; + cleancache_ops.init_fs = tmem_cleancache_init_fs; + printk(KERN_INFO "cleancache enabled, RAM provided by " + "Xen Transcendent Memory\n"); + } +#endif + return 0; +} + +module_init(xen_tmem_init) diff -Napur linux-2.6.35-rc4/include/xen/interface/xen.h linux-2.6.35-rc4-cleancache_tmem/include/xen/interface/xen.h --- linux-2.6.35-rc4/include/xen/interface/xen.h 2010-07-04 21:22:50.000000000 -0600 +++ linux-2.6.35-rc4-cleancache_tmem/include/xen/interface/xen.h 2010-07-07 16:24:06.000000000 -0600 @@ -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 +462,25 @@ typedef uint8_t xen_domain_handle_t[16]; #define __mk_unsigned_long(x) x ## UL #define mk_unsigned_long(x) __mk_unsigned_long(x) +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 object; + 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. */ -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
