aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--Documentation/cpusets.txt76
-rw-r--r--include/linux/cpuset.h29
-rw-r--r--include/linux/sched.h3
-rw-r--r--kernel/cpuset.c104
4 files changed, 203 insertions, 9 deletions
diff --git a/Documentation/cpusets.txt b/Documentation/cpusets.txt
index 30c41459953..159e2a0c3e8 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 3bc60692711..9354722a921 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 e60a91d5b36..b0e37cfa09f 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 44d13c246e5..38f18b33de6 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.
*