[PATCH V3 3/8] Cleancache: core ops functions and configuration Cleancache core ops functions and configuration
Credits: Cleancache_ops design derived from Jeremy Fitzhardinge design for tmem; sysfs code modelled after mm/ksm.c Note that CONFIG_CLEANCACHE defaults to on; all hooks devolve to a compare-function-pointer-to-NULL so performance impact should be negligible, but can be reduced to zero impact if config'ed off. Signed-off-by: Dan Magenheimer <[email protected]> Diffstat: include/linux/cleancache.h | 88 ++++++++++ mm/Kconfig | 22 ++ mm/Makefile | 1 mm/cleancache.c | 169 +++++++++++++++++++++ 4 files changed, 280 insertions(+) --- linux-2.6.35-rc2/include/linux/cleancache.h 1969-12-31 17:00:00.000000000 -0700 +++ linux-2.6.35-rc2-cleancache/include/linux/cleancache.h 2010-06-21 14:45:18.000000000 -0600 @@ -0,0 +1,88 @@ +#ifndef _LINUX_CLEANCACHE_H +#define _LINUX_CLEANCACHE_H + +#include <linux/fs.h> +#include <linux/mm.h> + +struct cleancache_ops { + int (*init_fs)(size_t); + int (*init_shared_fs)(char *uuid, size_t); + int (*get_page)(int, ino_t, pgoff_t, struct page *); + void (*put_page)(int, ino_t, pgoff_t, struct page *); + void (*flush_page)(int, ino_t, pgoff_t); + void (*flush_inode)(int, ino_t); + void (*flush_fs)(int); +}; + +extern struct cleancache_ops cleancache_ops; +extern int __cleancache_get_page(struct page *); +extern void __cleancache_put_page(struct page *); +extern void __cleancache_flush_page(struct address_space *, struct page *); +extern void __cleancache_flush_inode(struct address_space *); + +#ifdef CONFIG_CLEANCACHE +#define cleancache_enabled (cleancache_ops.init_fs) +#else +#define cleancache_enabled (0) +#endif + +/* called by a cleancache-enabled filesystem at time of mount */ +static inline int cleancache_init_fs(size_t pagesize) +{ + int ret = -1; + + if (cleancache_enabled) + ret = (*cleancache_ops.init_fs)(pagesize); + return ret; +} + +/* called by a cleancache-enabled clustered filesystem at time of mount */ +static inline int cleancache_init_shared_fs(char *uuid, size_t pagesize) +{ + int ret = -1; + + if (cleancache_enabled) + ret = (*cleancache_ops.init_shared_fs)(uuid, pagesize); + return ret; +} + +static inline int cleancache_get_page(struct page *page) +{ + int ret = -1; + + if (cleancache_enabled) + ret = __cleancache_get_page(page); + return ret; +} + +static inline void cleancache_put_page(struct page *page) +{ + if (cleancache_enabled) + __cleancache_put_page(page); +} + +static inline void cleancache_flush_page(struct address_space *mapping, + struct page *page) +{ + if (cleancache_enabled) + __cleancache_flush_page(mapping, page); +} + +static inline void cleancache_flush_inode(struct address_space *mapping) +{ + if (cleancache_enabled) + __cleancache_flush_inode(mapping); +} + +/* + * called by any cleancache-enabled filesystem at time of unmount; + * note that pool_id is surrendered and may be returned by a subsequent + * cleancache_init_fs or cleancache_init_shared_fs + */ +static inline void cleancache_flush_fs(int pool_id) +{ + if (cleancache_enabled && pool_id >= 0) + (*cleancache_ops.flush_fs)(pool_id); +} + +#endif /* _LINUX_CLEANCACHE_H */ --- linux-2.6.35-rc2/mm/cleancache.c 1969-12-31 17:00:00.000000000 -0700 +++ linux-2.6.35-rc2-cleancache/mm/cleancache.c 2010-06-11 10:32:35.000000000 -0600 @@ -0,0 +1,169 @@ +/* + * Cleancache frontend + * + * This code provides the generic "frontend" layer to call a matching + * "backend" driver implementation of cleancache. See + * Documentation/vm/cleancache.txt for more information. + * + * Copyright (C) 2009-2010 Oracle Corp. All rights reserved. + * Author: Dan Magenheimer + * + * This work is licensed under the terms of the GNU GPL, version 2. + */ + +#include <linux/module.h> +#include <linux/fs.h> +#include <linux/mm.h> +#include <linux/cleancache.h> + +/* + * cleancache_ops contains the pointers to the cleancache "backend" + * implementation functions + */ +struct cleancache_ops cleancache_ops; +EXPORT_SYMBOL(cleancache_ops); + +/* useful stats available in /sys/kernel/mm/cleancache */ +static unsigned long succ_gets; +static unsigned long failed_gets; +static unsigned long puts; +static unsigned long flushes; + +/* + * "Get" data from cleancache associated with the poolid/inode/index + * that were specified when the data was put to cleanache and, if + * successful, use it to fill the specified page with data and return 0. + * The pageframe is unchanged and returns -1 if the get fails. + * Page must be locked by caller. + */ +int __cleancache_get_page(struct page *page) +{ + int ret = -1; + int pool_id; + + VM_BUG_ON(!PageLocked(page)); + pool_id = page->mapping->host->i_sb->cleancache_poolid; + if (pool_id >= 0) { + ret = (*cleancache_ops.get_page)(pool_id, + page->mapping->host->i_ino, + page->index, + page); + if (ret == 0) + succ_gets++; + else + failed_gets++; + } + return ret; +} +EXPORT_SYMBOL(__cleancache_get_page); + +/* + * "Put" data from a page to cleancache and associate it with the + * (previously-obtained per-filesystem) poolid and the page's, + * inode and page index. Page must be locked. Note that a put_page + * always "succeeds", though a subsequent get_page may succeed or fail. + */ +void __cleancache_put_page(struct page *page) +{ + int pool_id; + + VM_BUG_ON(!PageLocked(page)); + pool_id = page->mapping->host->i_sb->cleancache_poolid; + if (pool_id >= 0) { + (*cleancache_ops.put_page)(pool_id, page->mapping->host->i_ino, + page->index, page); + puts++; + } +} + +/* + * Flush any data from cleancache associated with the poolid and the + * page's inode and page index so that a subsequent "get" will fail. + */ +void __cleancache_flush_page(struct address_space *mapping, struct page *page) +{ + int pool_id = mapping->host->i_sb->cleancache_poolid; + + if (pool_id >= 0) { + VM_BUG_ON(!PageLocked(page)); + (*cleancache_ops.flush_page)(pool_id, mapping->host->i_ino, + page->index); + flushes++; + } +} +EXPORT_SYMBOL(__cleancache_flush_page); + +/* + * Flush all data from cleancache associated with the poolid and the + * mappings's inode so that all subsequent gets to this poolid/inode + * will fail. + */ +void __cleancache_flush_inode(struct address_space *mapping) +{ + int pool_id = mapping->host->i_sb->cleancache_poolid; + + if (pool_id >= 0) + (*cleancache_ops.flush_inode)(pool_id, mapping->host->i_ino); +} +EXPORT_SYMBOL(__cleancache_flush_inode); + +#ifdef CONFIG_SYSFS + +/* see Documentation/ABI/xxx/sysfs-kernel-mm-cleancache */ + +#define CLEANCACHE_ATTR_RO(_name) \ + static struct kobj_attribute _name##_attr = __ATTR_RO(_name) + +static ssize_t succ_gets_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sprintf(buf, "%lu\n", succ_gets); +} +CLEANCACHE_ATTR_RO(succ_gets); + +static ssize_t failed_gets_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sprintf(buf, "%lu\n", failed_gets); +} +CLEANCACHE_ATTR_RO(failed_gets); + +static ssize_t puts_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sprintf(buf, "%lu\n", puts); +} +CLEANCACHE_ATTR_RO(puts); + +static ssize_t flushes_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sprintf(buf, "%lu\n", flushes); +} +CLEANCACHE_ATTR_RO(flushes); + +static struct attribute *cleancache_attrs[] = { + &succ_gets_attr.attr, + &failed_gets_attr.attr, + &puts_attr.attr, + &flushes_attr.attr, + NULL, +}; + +static struct attribute_group cleancache_attr_group = { + .attrs = cleancache_attrs, + .name = "cleancache", +}; + +#endif /* CONFIG_SYSFS */ + +static int __init init_cleancache(void) +{ +#ifdef CONFIG_SYSFS + int err; + + err = sysfs_create_group(mm_kobj, &cleancache_attr_group); +#endif /* CONFIG_SYSFS */ + return 0; +} +module_init(init_cleancache) --- linux-2.6.35-rc2/mm/Kconfig 2010-06-05 21:43:24.000000000 -0600 +++ linux-2.6.35-rc2-cleancache/mm/Kconfig 2010-06-11 09:01:37.000000000 -0600 @@ -298,3 +298,25 @@ config NOMMU_INITIAL_TRIM_EXCESS of 1 says that all excess pages should be trimmed. See Documentation/nommu-mmap.txt for more information. + +config CLEANCACHE + bool "Enable cleancache pseudo-RAM driver to cache clean pages" + default y + help + Cleancache can be thought of as a page-granularity victim cache + for clean pages that the kernel's pageframe replacement algorithm + (PFRA) would like to keep around, but can't since there isn't enough + memory. So when the PFRA "evicts" a page, it first attempts to put + it into a synchronous concurrency-safe page-oriented pseudo-RAM + device (such as Xen's Transcendent Memory, aka "tmem") which is not + directly accessible or addressable by the kernel and is of unknown + (and possibly time-varying) size. And when a cleancache-enabled + filesystem wishes to access a page in a file on disk, it first + checks cleancache to see if it already contains it; if it does, + the page is copied into the kernel and a disk access is avoided. + When a pseudo-RAM device is available, a significant I/O reduction + may be achieved. When none is available, all cleancache calls + are reduced to a single pointer-compare-against-NULL resulting + in a negligible performance hit. + + If unsure, say Y to enable cleancache --- linux-2.6.35-rc2/mm/Makefile 2010-06-05 21:43:24.000000000 -0600 +++ linux-2.6.35-rc2-cleancache/mm/Makefile 2010-06-11 09:01:37.000000000 -0600 @@ -45,3 +45,4 @@ obj-$(CONFIG_MEMORY_FAILURE) += memory-f obj-$(CONFIG_HWPOISON_INJECT) += hwpoison-inject.o obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o +obj-$(CONFIG_CLEANCACHE) += cleancache.o _______________________________________________ Ocfs2-devel mailing list [email protected] http://oss.oracle.com/mailman/listinfo/ocfs2-devel
