diff options
| -rw-r--r-- | Documentation/cpusets.txt | 76 | ||||
| -rw-r--r-- | include/linux/cpuset.h | 29 | ||||
| -rw-r--r-- | include/linux/sched.h | 3 | ||||
| -rw-r--r-- | kernel/cpuset.c | 104 |
4 files changed, 203 insertions, 9 deletions
diff --git a/Documentation/cpusets.txt b/Documentation/cpusets.txt index 30c4145..159e2a0 100644 --- a/Documentation/cpusets.txt +++ b/Documentation/cpusets.txt @@ -18,7 +18,8 @@ CONTENTS: 1.4 What are exclusive cpusets ? 1.5 What does notify_on_release do ? 1.6 What is memory_pressure ? - 1.7 How do I use cpusets ? + 1.7 What is memory spread ? + 1.8 How do I use cpusets ? 2. Usage Examples and Syntax 2.1 Basic Usage 2.2 Adding/removing cpus @@ -317,7 +318,78 @@ the tasks in the cpuset, in units of reclaims attempted per second, times 1000. -1.7 How do I use cpusets ? +1.7 What is memory spread ? +--------------------------- +There are two boolean flag files per cpuset that control where the +kernel allocates pages for the file system buffers and related in +kernel data structures. They are called 'memory_spread_page' and +'memory_spread_slab'. + +If the per-cpuset boolean flag file 'memory_spread_page' is set, then +the kernel will spread the file system buffers (page cache) evenly +over all the nodes that the faulting task is allowed to use, instead +of preferring to put those pages on the node where the task is running. + +If the per-cpuset boolean flag file 'memory_spread_slab' is set, +then the kernel will spread some file system related slab caches, +such as for inodes and dentries evenly over all the nodes that the +faulting task is allowed to use, instead of preferring to put those +pages on the node where the task is running. + +The setting of these flags does not affect anonymous data segment or +stack segment pages of a task. + +By default, both kinds of memory spreading are off, and memory +pages are allocated on the node local to where the task is running, +except perhaps as modified by the tasks NUMA mempolicy or cpuset +configuration, so long as sufficient free memory pages are available. + +When new cpusets are created, they inherit the memory spread settings +of their parent. + +Setting memory spreading causes allocations for the affected page +or slab caches to ignore the tasks NUMA mempolicy and be spread +instead. Tasks using mbind() or set_mempolicy() calls to set NUMA +mempolicies will not notice any change in these calls as a result of +their containing tasks memory spread settings. If memory spreading +is turned off, then the currently specified NUMA mempolicy once again +applies to memory page allocations. + +Both 'memory_spread_page' and 'memory_spread_slab' are boolean flag +files. By default they contain "0", meaning that the feature is off +for that cpuset. If a "1" is written to that file, then that turns +the named feature on. + +The implementation is simple. + +Setting the flag 'memory_spread_page' turns on a per-process flag +PF_SPREAD_PAGE for each task that is in that cpuset or subsequently +joins that cpuset. The page allocation calls for the page cache +is modified to perform an inline check for this PF_SPREAD_PAGE task +flag, and if set, a call to a new routine cpuset_mem_spread_node() +returns the node to prefer for the allocation. + +Similarly, setting 'memory_spread_cache' turns on the flag +PF_SPREAD_SLAB, and appropriately marked slab caches will allocate +pages from the node returned by cpuset_mem_spread_node(). + +The cpuset_mem_spread_node() routine is also simple. It uses the +value of a per-task rotor cpuset_mem_spread_rotor to select the next +node in the current tasks mems_allowed to prefer for the allocation. + +This memory placement policy is also known (in other contexts) as +round-robin or interleave. + +This policy can provide substantial improvements for jobs that need +to place thread local data on the corresponding node, but that need +to access large file system data sets that need to be spread across +the several nodes in the jobs cpuset in order to fit. Without this +policy, especially for jobs that might have one thread reading in the +data set, the memory allocation across the nodes in the jobs cpuset +can become very uneven. + + +1.8 How do I use cpusets ? -------------------------- In order to minimize the impact of cpusets on critical kernel diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index 3bc6069..9354722 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -4,7 +4,7 @@ * cpuset interface * * Copyright (C) 2003 BULL SA - * Copyright (C) 2004 Silicon Graphics, Inc. + * Copyright (C) 2004-2006 Silicon Graphics, Inc. * */ @@ -51,6 +51,18 @@ extern char *cpuset_task_status_allowed(struct task_struct *task, char *buffer); extern void cpuset_lock(void); extern void cpuset_unlock(void); +extern int cpuset_mem_spread_node(void); + +static inline int cpuset_do_page_mem_spread(void) +{ + return current->flags & PF_SPREAD_PAGE; +} + +static inline int cpuset_do_slab_mem_spread(void) +{ + return current->flags & PF_SPREAD_SLAB; +} + #else /* !CONFIG_CPUSETS */ static inline int cpuset_init_early(void) { return 0; } @@ -99,6 +111,21 @@ static inline char *cpuset_task_status_allowed(struct task_struct *task, static inline void cpuset_lock(void) {} static inline void cpuset_unlock(void) {} +static inline int cpuset_mem_spread_node(void) +{ + return 0; +} + +static inline int cpuset_do_page_mem_spread(void) +{ + return 0; +} + +static inline int cpuset_do_slab_mem_spread(void) +{ + return 0; +} + #endif /* !CONFIG_CPUSETS */ #endif /* _LINUX_CPUSET_H */ diff --git a/include/linux/sched.h b/include/linux/sched.h index e60a91d..b0e37cf 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -869,6 +869,7 @@ struct task_struct { struct cpuset *cpuset; nodemask_t mems_allowed; int cpuset_mems_generation; + int cpuset_mem_spread_rotor; #endif atomic_t fs_excl; /* holding fs exclusive resources */ struct rcu_head rcu; @@ -929,6 +930,8 @@ static inline void put_task_struct(struct task_struct *t) #define PF_BORROWED_MM 0x00400000 /* I am a kthread doing use_mm */ #define PF_RANDOMIZE 0x00800000 /* randomize virtual address space */ #define PF_SWAPWRITE 0x01000000 /* Allowed to write to swap */ +#define PF_SPREAD_PAGE 0x04000000 /* Spread page cache over cpuset */ +#define PF_SPREAD_SLAB 0x08000000 /* Spread some slab caches over cpuset */ /* * Only the _current_ task can read/write to tsk->flags, but other diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 44d13c2..38f18b3 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -4,15 +4,14 @@ * Processor and Memory placement constraints for sets of tasks. * * Copyright (C) 2003 BULL SA. - * Copyright (C) 2004 Silicon Graphics, Inc. + * Copyright (C) 2004-2006 Silicon Graphics, Inc. * * Portions derived from Patrick Mochel's sysfs code. * sysfs is Copyright (c) 2001-3 Patrick Mochel - * Portions Copyright (c) 2004 Silicon Graphics, Inc. * - * 2003-10-10 Written by Simon Derr <simon.derr@bull.net> + * 2003-10-10 Written by Simon Derr. * 2003-10-22 Updates by Stephen Hemminger. - * 2004 May-July Rework by Paul Jackson <pj@sgi.com> + * 2004 May-July Rework by Paul Jackson. * * This file is subject to the terms and conditions of the GNU General Public * License. See the file COPYING in the main directory of the Linux @@ -108,7 +107,9 @@ typedef enum { CS_MEM_EXCLUSIVE, CS_MEMORY_MIGRATE, CS_REMOVED, - CS_NOTIFY_ON_RELEASE + CS_NOTIFY_ON_RELEASE, + CS_SPREAD_PAGE, + CS_SPREAD_SLAB, } cpuset_flagbits_t; /* convenient tests for these bits */ @@ -137,6 +138,16 @@ static inline int is_memory_migrate(const struct cpuset *cs) return test_bit(CS_MEMORY_MIGRATE, &cs->flags); } +static inline int is_spread_page(const struct cpuset *cs) +{ + return test_bit(CS_SPREAD_PAGE, &cs->flags); +} + +static inline int is_spread_slab(const struct cpuset *cs) +{ + return test_bit(CS_SPREAD_SLAB, &cs->flags); +} + /* * Increment this atomic integer everytime any cpuset changes its * mems_allowed value. Users of cpusets can track this generation @@ -657,6 +668,14 @@ void cpuset_update_task_memory_state(void) cs = tsk->cpuset; /* Maybe changed when task not locked */ guarantee_online_mems(cs, &tsk->mems_allowed); tsk->cpuset_mems_generation = cs->mems_generation; + if (is_spread_page(cs)) + tsk->flags |= PF_SPREAD_PAGE; + else + tsk->flags &= ~PF_SPREAD_PAGE; + if (is_spread_slab(cs)) + tsk->flags |= PF_SPREAD_SLAB; + else + tsk->flags &= ~PF_SPREAD_SLAB; task_unlock(tsk); mutex_unlock(&callback_mutex); mpol_rebind_task(tsk, &tsk->mems_allowed); @@ -956,7 +975,8 @@ static int update_memory_pressure_enabled(struct cpuset *cs, char *buf) /* * update_flag - read a 0 or a 1 in a file and update associated flag * bit: the bit to update (CS_CPU_EXCLUSIVE, CS_MEM_EXCLUSIVE, - * CS_NOTIFY_ON_RELEASE, CS_MEMORY_MIGRATE) + * CS_NOTIFY_ON_RELEASE, CS_MEMORY_MIGRATE, + * CS_SPREAD_PAGE, CS_SPREAD_SLAB) * cs: the cpuset to update * buf: the buffer where we read the 0 or 1 * @@ -1187,6 +1207,8 @@ typedef enum { FILE_NOTIFY_ON_RELEASE, FILE_MEMORY_PRESSURE_ENABLED, FILE_MEMORY_PRESSURE, + FILE_SPREAD_PAGE, + FILE_SPREAD_SLAB, FILE_TASKLIST, } cpuset_filetype_t; @@ -1246,6 +1268,14 @@ static ssize_t cpuset_common_file_write(struct file *file, const char __user *us case FILE_MEMORY_PRESSURE: retval = -EACCES; break; + case FILE_SPREAD_PAGE: + retval = update_flag(CS_SPREAD_PAGE, cs, buffer); + cs->mems_generation = atomic_inc_return(&cpuset_mems_generation); + break; + case FILE_SPREAD_SLAB: + retval = update_flag(CS_SPREAD_SLAB, cs, buffer); + cs->mems_generation = atomic_inc_return(&cpuset_mems_generation); + break; case FILE_TASKLIST: retval = attach_task(cs, buffer, &pathbuf); break; @@ -1355,6 +1385,12 @@ static ssize_t cpuset_common_file_read(struct file *file, char __user *buf, case FILE_MEMORY_PRESSURE: s += sprintf(s, "%d", fmeter_getrate(&cs->fmeter)); break; + case FILE_SPREAD_PAGE: + *s++ = is_spread_page(cs) ? '1' : '0'; + break; + case FILE_SPREAD_SLAB: + *s++ = is_spread_slab(cs) ? '1' : '0'; + break; default: retval = -EINVAL; goto out; @@ -1718,6 +1754,16 @@ static struct cftype cft_memory_pressure = { .private = FILE_MEMORY_PRESSURE, }; +static struct cftype cft_spread_page = { + .name = "memory_spread_page", + .private = FILE_SPREAD_PAGE, +}; + +static struct cftype cft_spread_slab = { + .name = "memory_spread_slab", + .private = FILE_SPREAD_SLAB, +}; + static int cpuset_populate_dir(struct dentry *cs_dentry) { int err; @@ -1736,6 +1782,10 @@ static int cpuset_populate_dir(struct dentry *cs_dentry) return err; if ((err = cpuset_add_file(cs_dentry, &cft_memory_pressure)) < 0) return err; + if ((err = cpuset_add_file(cs_dentry, &cft_spread_page)) < 0) + return err; + if ((err = cpuset_add_file(cs_dentry, &cft_spread_slab)) < 0) + return err; if ((err = cpuset_add_file(cs_dentry, &cft_tasks)) < 0) return err; return 0; @@ -1764,6 +1814,10 @@ static long cpuset_create(struct cpuset *parent, const char *name, int mode) cs->flags = 0; if (notify_on_release(parent)) set_bit(CS_NOTIFY_ON_RELEASE, &cs->flags); + if (is_spread_page(parent)) + set_bit(CS_SPREAD_PAGE, &cs->flags); + if (is_spread_slab(parent)) + set_bit(CS_SPREAD_SLAB, &cs->flags); cs->cpus_allowed = CPU_MASK_NONE; cs->mems_allowed = NODE_MASK_NONE; atomic_set(&cs->count, 0); @@ -2201,6 +2255,44 @@ void cpuset_unlock(void) } /** + * cpuset_mem_spread_node() - On which node to begin search for a page + * + * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for + * tasks in a cpuset with is_spread_page or is_spread_slab set), + * and if the memory allocation used cpuset_mem_spread_node() + * to determine on which node to start looking, as it will for + * certain page cache or slab cache pages such as used for file + * system buffers and inode caches, then instead of starting on the + * local node to look for a free page, rather spread the starting + * node around the tasks mems_allowed nodes. + * + * We don't have to worry about the returned node being offline + * because "it can't happen", and even if it did, it would be ok. + * + * The routines calling guarantee_online_mems() are careful to + * only set nodes in task->mems_allowed that are online. So it + * should not be possible for the following code to return an + * offline node. But if it did, that would be ok, as this routine + * is not returning the node where the allocation must be, only + * the node where the search should start. The zonelist passed to + * __alloc_pages() will include all nodes. If the slab allocator + * is passed an offline node, it will fall back to the local node. + * See kmem_cache_alloc_node(). + */ + +int cpuset_mem_spread_node(void) +{ + int node; + + node = next_node(current->cpuset_mem_spread_rotor, current->mems_allowed); + if (node == MAX_NUMNODES) + node = first_node(current->mems_allowed); + current->cpuset_mem_spread_rotor = node; + return node; +} +EXPORT_SYMBOL_GPL(cpuset_mem_spread_node); + +/** * cpuset_excl_nodes_overlap - Do we overlap @p's mem_exclusive ancestors? * @p: pointer to task_struct of some other task. * |
