On Tue, May 27, 2014 at 6:06 PM, Seth Jennings <sjennings@xxxxxxxxxxxxxx> wrote: > On Sat, May 24, 2014 at 03:06:06PM -0400, Dan Streetman wrote: >> Add zpool api. >> >> zpool provides an interface for memory storage, typically of compressed >> memory. Users can select what backend to use; currently the only >> implementations are zbud, a low density implementation with up to >> two compressed pages per storage page, and zsmalloc, a higher density >> implementation with multiple compressed pages per storage page. >> >> Signed-off-by: Dan Streetman <ddstreet@xxxxxxxx> >> Cc: Seth Jennings <sjennings@xxxxxxxxxxxxxx> >> Cc: Minchan Kim <minchan@xxxxxxxxxx> >> Cc: Nitin Gupta <ngupta@xxxxxxxxxx> >> Cc: Weijie Yang <weijie.yang@xxxxxxxxxxx> >> --- >> >> Note this patch set is against the mmotm tree at >> git://git.cmpxchg.org/linux-mmotm.git >> This patch may need context changes to the -next or other trees. >> >> Changes since v2 : https://lkml.org/lkml/2014/5/7/733 >> -Remove hardcoded zbud/zsmalloc implementations >> -Add driver (un)register functions >> >> Changes since v1 https://lkml.org/lkml/2014/4/19/101 >> -add some pr_info() during creation and pr_err() on errors >> -remove zpool code to call zs_shrink(), since zsmalloc shrinking >> was removed from this patchset >> -remove fallback; only specified pool type will be tried >> -pr_fmt() is defined in zpool to prefix zpool: in any pr_XXX() calls >> >> >> include/linux/zpool.h | 214 ++++++++++++++++++++++++++++++++++++++++++++++++++ >> mm/Kconfig | 41 ++++++---- >> mm/Makefile | 1 + >> mm/zpool.c | 197 ++++++++++++++++++++++++++++++++++++++++++++++ >> 4 files changed, 436 insertions(+), 17 deletions(-) >> create mode 100644 include/linux/zpool.h >> create mode 100644 mm/zpool.c >> >> diff --git a/include/linux/zpool.h b/include/linux/zpool.h >> new file mode 100644 >> index 0000000..699ac9b >> --- /dev/null >> +++ b/include/linux/zpool.h >> @@ -0,0 +1,214 @@ >> +/* >> + * zpool memory storage api >> + * >> + * Copyright (C) 2014 Dan Streetman >> + * >> + * This is a common frontend for the zbud and zsmalloc memory >> + * storage pool implementations. Typically, this is used to >> + * store compressed memory. >> + */ >> + >> +#ifndef _ZPOOL_H_ >> +#define _ZPOOL_H_ >> + >> +struct zpool; >> + >> +struct zpool_ops { >> + int (*evict)(struct zpool *pool, unsigned long handle); >> +}; >> + >> +/* >> + * Control how a handle is mapped. It will be ignored if the >> + * implementation does not support it. Its use is optional. >> + * Note that this does not refer to memory protection, it >> + * refers to how the memory will be copied in/out if copying >> + * is necessary during mapping; read-write is the safest as >> + * it copies the existing memory in on map, and copies the >> + * changed memory back out on unmap. Write-only does not copy >> + * in the memory and should only be used for initialization. >> + * If in doubt, use ZPOOL_MM_DEFAULT which is read-write. >> + */ >> +enum zpool_mapmode { >> + ZPOOL_MM_RW, /* normal read-write mapping */ >> + ZPOOL_MM_RO, /* read-only (no copy-out at unmap time) */ >> + ZPOOL_MM_WO, /* write-only (no copy-in at map time) */ >> + >> + ZPOOL_MM_DEFAULT = ZPOOL_MM_RW >> +}; >> + >> +/** >> + * zpool_create_pool() - Create a new zpool >> + * @type The type of the zpool to create (e.g. zbud, zsmalloc) >> + * @flags What GFP flags should be used when the zpool allocates memory. >> + * @ops The optional ops callback. >> + * >> + * This creates a new zpool of the specified type. The zpool will use the >> + * given flags when allocating any memory. If the ops param is NULL, then >> + * the created zpool will not be shrinkable. >> + * >> + * Returns: New zpool on success, NULL on failure. >> + */ >> +struct zpool *zpool_create_pool(char *type, gfp_t flags, >> + struct zpool_ops *ops); >> + >> +/** >> + * zpool_get_type() - Get the type of the zpool >> + * @pool The zpool to check >> + * >> + * This returns the type of the pool. >> + * >> + * Returns: The type of zpool. >> + */ >> +char *zpool_get_type(struct zpool *pool); >> + >> +/** >> + * zpool_destroy_pool() - Destroy a zpool >> + * @pool The zpool to destroy. >> + * >> + * This destroys an existing zpool. The zpool should not be in use. >> + */ >> +void zpool_destroy_pool(struct zpool *pool); >> + >> +/** >> + * zpool_malloc() - Allocate memory >> + * @pool The zpool to allocate from. >> + * @size The amount of memory to allocate. >> + * @handle Pointer to the handle to set >> + * >> + * This allocates the requested amount of memory from the pool. >> + * The provided @handle will be set to the allocated object handle. >> + * >> + * Returns: 0 on success, negative value on error. >> + */ >> +int zpool_malloc(struct zpool *pool, size_t size, unsigned long *handle); >> + >> +/** >> + * zpool_free() - Free previously allocated memory >> + * @pool The zpool that allocated the memory. >> + * @handle The handle to the memory to free. >> + * >> + * This frees previously allocated memory. This does not guarantee >> + * that the pool will actually free memory, only that the memory >> + * in the pool will become available for use by the pool. >> + */ >> +void zpool_free(struct zpool *pool, unsigned long handle); >> + >> +/** >> + * zpool_shrink() - Shrink the pool size >> + * @pool The zpool to shrink. >> + * @size The minimum amount to shrink the pool. >> + * >> + * This attempts to shrink the actual memory size of the pool >> + * by evicting currently used handle(s). If the pool was >> + * created with no zpool_ops, or the evict call fails for any >> + * of the handles, this will fail. >> + * >> + * Returns: 0 on success, negative value on error/failure. >> + */ >> +int zpool_shrink(struct zpool *pool, size_t size); > > This should take a number of pages to be reclaimed, not a size. The > user can evict their own object to reclaim a certain number of bytes > from the pool. What the user can't do is reclaim a page since it is not > aware of the arrangement of the stored objects in the memory pages. Yes I suppose that's true, I'll update it for v4... > > Also in patch 5/6 of six I see: > > - if (zbud_reclaim_page(zswap_pool, 8)) { > + if (zpool_shrink(zswap_pool, PAGE_SIZE)) { > > but then in 4/6 I see: > > +int zbud_zpool_shrink(void *pool, size_t size) > +{ > + return zbud_reclaim_page(pool, 8); > +} > > That is why it didn't completely explode on you since the zbud logic > is still reclaiming pages. Ha, yes clearly I neglected to translate between the size and the number of pages there, oops! On this topic - 8 retries seems very arbitrary. Does it make sense to include retrying in zbud and/or zpool at all? The caller can easily retry any number of times themselves, especially since zbud (and eventually zsmalloc) will return -EAGAIN if the caller should retry. > >> + >> +/** >> + * zpool_map_handle() - Map a previously allocated handle into memory >> + * @pool The zpool that the handle was allocated from >> + * @handle The handle to map >> + * @mm How the memory should be mapped >> + * >> + * This maps a previously allocated handle into memory. The @mm >> + * param indicates to the implemenation how the memory will be >> + * used, i.e. read-only, write-only, read-write. If the >> + * implementation does not support it, the memory will be treated >> + * as read-write. >> + * >> + * This may hold locks, disable interrupts, and/or preemption, >> + * and the zpool_unmap_handle() must be called to undo those >> + * actions. The code that uses the mapped handle should complete >> + * its operatons on the mapped handle memory quickly and unmap >> + * as soon as possible. Multiple handles should not be mapped >> + * concurrently on a cpu. >> + * >> + * Returns: A pointer to the handle's mapped memory area. >> + */ >> +void *zpool_map_handle(struct zpool *pool, unsigned long handle, >> + enum zpool_mapmode mm); >> + >> +/** >> + * zpool_unmap_handle() - Unmap a previously mapped handle >> + * @pool The zpool that the handle was allocated from >> + * @handle The handle to unmap >> + * >> + * This unmaps a previously mapped handle. Any locks or other >> + * actions that the implemenation took in zpool_map_handle() >> + * will be undone here. The memory area returned from >> + * zpool_map_handle() should no longer be used after this. >> + */ >> +void zpool_unmap_handle(struct zpool *pool, unsigned long handle); >> + >> +/** >> + * zpool_get_total_size() - The total size of the pool >> + * @pool The zpool to check >> + * >> + * This returns the total size in bytes of the pool. >> + * >> + * Returns: Total size of the zpool in bytes. >> + */ >> +u64 zpool_get_total_size(struct zpool *pool); >> + >> + >> +/** >> + * struct zpool_driver - driver implementation for zpool >> + * @type: name of the driver. >> + * @list: entry in the list of zpool drivers. >> + * @create: create a new pool. >> + * @destroy: destroy a pool. >> + * @malloc: allocate mem from a pool. >> + * @free: free mem from a pool. >> + * @shrink: shrink the pool. >> + * @map: map a handle. >> + * @unmap: unmap a handle. >> + * @total_size: get total size of a pool. >> + * >> + * This is created by a zpool implementation and registered >> + * with zpool. >> + */ >> +struct zpool_driver { >> + char *type; >> + struct list_head list; >> + >> + void *(*create)(gfp_t gfp, struct zpool_ops *ops); >> + void (*destroy)(void *pool); >> + >> + int (*malloc)(void *pool, size_t size, unsigned long *handle); >> + void (*free)(void *pool, unsigned long handle); >> + >> + int (*shrink)(void *pool, size_t size); >> + >> + void *(*map)(void *pool, unsigned long handle, >> + enum zpool_mapmode mm); >> + void (*unmap)(void *pool, unsigned long handle); >> + >> + u64 (*total_size)(void *pool); >> +}; >> + >> +/** >> + * zpool_register_driver() - register a zpool implementation. >> + * @driver: driver to register >> + */ >> +void zpool_register_driver(struct zpool_driver *driver); >> + >> +/** >> + * zpool_unregister_driver() - unregister a zpool implementation. >> + * @driver: driver to unregister. >> + */ >> +void zpool_unregister_driver(struct zpool_driver *driver); >> + >> +/** >> + * zpool_evict() - evict callback from a zpool implementation. >> + * @pool: pool to evict from. >> + * @handle: handle to evict. >> + * >> + * This can be used by zpool implementations to call the >> + * user's evict zpool_ops struct evict callback. >> + */ >> +int zpool_evict(void *pool, unsigned long handle); >> + >> +#endif >> diff --git a/mm/Kconfig b/mm/Kconfig >> index 7511b4a..00f7720 100644 >> --- a/mm/Kconfig >> +++ b/mm/Kconfig >> @@ -515,15 +515,17 @@ config CMA_DEBUG >> processing calls such as dma_alloc_from_contiguous(). >> This option does not affect warning and error messages. >> >> -config ZBUD >> - tristate >> - default n >> +config MEM_SOFT_DIRTY >> + bool "Track memory changes" >> + depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS >> + select PROC_PAGE_MONITOR >> help >> - A special purpose allocator for storing compressed pages. >> - It is designed to store up to two compressed pages per physical >> - page. While this design limits storage density, it has simple and >> - deterministic reclaim properties that make it preferable to a higher >> - density approach when reclaim will be used. >> + This option enables memory changes tracking by introducing a >> + soft-dirty bit on pte-s. This bit it set when someone writes >> + into a page just as regular dirty bit, but unlike the latter >> + it can be cleared by hands. >> + >> + See Documentation/vm/soft-dirty.txt for more details. >> >> config ZSWAP >> bool "Compressed cache for swap pages (EXPERIMENTAL)" >> @@ -545,17 +547,22 @@ config ZSWAP >> they have not be fully explored on the large set of potential >> configurations and workloads that exist. >> >> -config MEM_SOFT_DIRTY >> - bool "Track memory changes" >> - depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS >> - select PROC_PAGE_MONITOR >> +config ZPOOL >> + tristate "Common API for compressed memory storage" >> + default n >> help >> - This option enables memory changes tracking by introducing a >> - soft-dirty bit on pte-s. This bit it set when someone writes >> - into a page just as regular dirty bit, but unlike the latter >> - it can be cleared by hands. >> + Compressed memory storage API. This allows using either zbud or >> + zsmalloc. >> >> - See Documentation/vm/soft-dirty.txt for more details. >> +config ZBUD >> + tristate "Low density storage for compressed pages" >> + default n >> + help >> + A special purpose allocator for storing compressed pages. >> + It is designed to store up to two compressed pages per physical >> + page. While this design limits storage density, it has simple and >> + deterministic reclaim properties that make it preferable to a higher >> + density approach when reclaim will be used. >> >> config ZSMALLOC >> tristate "Memory allocator for compressed pages" >> diff --git a/mm/Makefile b/mm/Makefile >> index 2b6fff2..759db04 100644 >> --- a/mm/Makefile >> +++ b/mm/Makefile >> @@ -61,6 +61,7 @@ obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o >> obj-$(CONFIG_CLEANCACHE) += cleancache.o >> obj-$(CONFIG_MEMORY_ISOLATION) += page_isolation.o >> obj-$(CONFIG_PAGE_OWNER) += pageowner.o >> +obj-$(CONFIG_ZPOOL) += zpool.o >> obj-$(CONFIG_ZBUD) += zbud.o >> obj-$(CONFIG_ZSMALLOC) += zsmalloc.o >> obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o >> diff --git a/mm/zpool.c b/mm/zpool.c >> new file mode 100644 >> index 0000000..89ed71f >> --- /dev/null >> +++ b/mm/zpool.c >> @@ -0,0 +1,197 @@ >> +/* >> + * zpool memory storage api >> + * >> + * Copyright (C) 2014 Dan Streetman >> + * >> + * This is a common frontend for memory storage pool implementations. >> + * Typically, this is used to store compressed memory. >> + */ >> + >> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt >> + >> +#include <linux/list.h> >> +#include <linux/types.h> >> +#include <linux/mm.h> >> +#include <linux/slab.h> >> +#include <linux/spinlock.h> >> +#include <linux/module.h> >> +#include <linux/zpool.h> >> + >> +struct zpool { >> + char *type; >> + >> + struct zpool_driver *driver; >> + void *pool; >> + struct zpool_ops *ops; >> + >> + struct list_head list; >> +}; >> + >> +static LIST_HEAD(drivers_head); >> +static DEFINE_SPINLOCK(drivers_lock); >> + >> +static LIST_HEAD(pools_head); >> +static DEFINE_SPINLOCK(pools_lock); >> + >> +void zpool_register_driver(struct zpool_driver *driver) >> +{ >> + spin_lock(&drivers_lock); >> + list_add(&driver->list, &drivers_head); >> + spin_unlock(&drivers_lock); >> +} >> +EXPORT_SYMBOL(zpool_register_driver); >> + >> +void zpool_unregister_driver(struct zpool_driver *driver) >> +{ >> + spin_lock(&drivers_lock); >> + list_del(&driver->list); >> + spin_unlock(&drivers_lock); >> +} >> +EXPORT_SYMBOL(zpool_unregister_driver); >> + >> +int zpool_evict(void *pool, unsigned long handle) >> +{ >> + struct zpool *zpool; >> + >> + spin_lock(&pools_lock); >> + list_for_each_entry(zpool, &pools_head, list) { > > You can do a container_of() here: > > zpool = container_of(pool, struct zpool, pool); unfortunately, that's not true, since the driver pool isn't actually a member of the struct zpool. The struct zpool only has a pointer to the driver pool. I really wanted to use container_of(), but I think zbud/zsmalloc would need alternate pool creation functions that create struct zpools of the appropriate size with their pool embedded, and the driver->create() function would need to alloc and return the entire struct zpool, instead of just the driver pool. Do you think that's a better approach? Or is there another better way I'm missing? > > Seth > >> + if (zpool->pool == pool) { >> + spin_unlock(&pools_lock); >> + if (!zpool->ops || !zpool->ops->evict) >> + return -EINVAL; >> + return zpool->ops->evict(zpool, handle); >> + } >> + } >> + spin_unlock(&pools_lock); >> + >> + return -ENOENT; >> +} >> +EXPORT_SYMBOL(zpool_evict); >> + >> +static struct zpool_driver *zpool_get_driver(char *type) >> +{ >> + struct zpool_driver *driver; >> + >> + assert_spin_locked(&drivers_lock); >> + list_for_each_entry(driver, &drivers_head, list) { >> + if (!strcmp(driver->type, type)) >> + return driver; >> + } >> + >> + return NULL; >> +} >> + >> +struct zpool *zpool_create_pool(char *type, gfp_t flags, >> + struct zpool_ops *ops) >> +{ >> + struct zpool_driver *driver; >> + struct zpool *zpool; >> + >> + pr_info("creating pool type %s\n", type); >> + >> + spin_lock(&drivers_lock); >> + driver = zpool_get_driver(type); >> + spin_unlock(&drivers_lock); >> + >> + if (!driver) { >> + request_module(type); >> + spin_lock(&drivers_lock); >> + driver = zpool_get_driver(type); >> + spin_unlock(&drivers_lock); >> + } >> + >> + if (!driver) { >> + pr_err("no driver for type %s\n", type); >> + return NULL; >> + } >> + >> + zpool = kmalloc(sizeof(*zpool), GFP_KERNEL); >> + if (!zpool) { >> + pr_err("couldn't create zpool - out of memory\n"); >> + return NULL; >> + } >> + >> + zpool->type = driver->type; >> + zpool->driver = driver; >> + zpool->pool = driver->create(flags, ops); >> + zpool->ops = ops; >> + >> + if (!zpool->pool) { >> + pr_err("couldn't create %s pool\n", type); >> + kfree(zpool); >> + return NULL; >> + } >> + >> + pr_info("created %s pool\n", type); >> + >> + spin_lock(&pools_lock); >> + list_add(&zpool->list, &pools_head); >> + spin_unlock(&pools_lock); >> + >> + return zpool; >> +} >> + >> +void zpool_destroy_pool(struct zpool *zpool) >> +{ >> + pr_info("destroying pool type %s\n", zpool->type); >> + >> + spin_lock(&pools_lock); >> + list_del(&zpool->list); >> + spin_unlock(&pools_lock); >> + zpool->driver->destroy(zpool->pool); >> + kfree(zpool); >> +} >> + >> +char *zpool_get_type(struct zpool *zpool) >> +{ >> + return zpool->type; >> +} >> + >> +int zpool_malloc(struct zpool *zpool, size_t size, unsigned long *handle) >> +{ >> + return zpool->driver->malloc(zpool->pool, size, handle); >> +} >> + >> +void zpool_free(struct zpool *zpool, unsigned long handle) >> +{ >> + zpool->driver->free(zpool->pool, handle); >> +} >> + >> +int zpool_shrink(struct zpool *zpool, size_t size) >> +{ >> + return zpool->driver->shrink(zpool->pool, size); >> +} >> + >> +void *zpool_map_handle(struct zpool *zpool, unsigned long handle, >> + enum zpool_mapmode mapmode) >> +{ >> + return zpool->driver->map(zpool->pool, handle, mapmode); >> +} >> + >> +void zpool_unmap_handle(struct zpool *zpool, unsigned long handle) >> +{ >> + zpool->driver->unmap(zpool->pool, handle); >> +} >> + >> +u64 zpool_get_total_size(struct zpool *zpool) >> +{ >> + return zpool->driver->total_size(zpool->pool); >> +} >> + >> +static int __init init_zpool(void) >> +{ >> + pr_info("loaded\n"); >> + return 0; >> +} >> + >> +static void __exit exit_zpool(void) >> +{ >> + pr_info("unloaded\n"); >> +} >> + >> +module_init(init_zpool); >> +module_exit(exit_zpool); >> + >> +MODULE_LICENSE("GPL"); >> +MODULE_AUTHOR("Dan Streetman <ddstreet@xxxxxxxx>"); >> +MODULE_DESCRIPTION("Common API for compressed memory storage"); >> -- >> 1.8.3.1 >> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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