[PATCH] Extract the allocpercpu functions from the slab allocator

[PATCH] Extract the allocpercpu functions from the slab allocator

[Christoph Lameter]

The allocpercpu functions __alloc_percpu and __free_percpu() are heavily 
using the slab allocator. However, they are conceptually different 
allocators that can be used independently from the slab. Currently the 
slab code is duplicated in slob. This patch also 
simplifies SLOB.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.18-rc4/mm/allocpercpu.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.18-rc4/mm/allocpercpu.c	2006-08-18 20:57:49.812228291 -0700
@@ -0,0 +1,76 @@
+/*
+ * linux/mm/allocpercpu.c
+ *
+ * From slab.c August,2006 Christoph Lameter <clameter@sgi.com>
+ */
+#include <linux/mm.h>
+#include <linux/module.h>
+
+/**
+ * __alloc_percpu - allocate one copy of the object for every present
+ * cpu in the system, zeroing them.
+ * Objects should be dereferenced using the per_cpu_ptr macro only.
+ *
+ * @size: how many bytes of memory are required.
+ */
+void *__alloc_percpu(size_t size)
+{
+	int i;
+	struct percpu_data *pdata = kmalloc(sizeof(*pdata), GFP_KERNEL);
+
+	if (!pdata)
+		return NULL;
+
+	/*
+	 * Cannot use for_each_online_cpu since a cpu may come online
+	 * and we have no way of figuring out how to fix the array
+	 * that we have allocated then....
+	 */
+	for_each_possible_cpu(i) {
+		int node = cpu_to_node(i);
+
+		if (node_online(node))
+			pdata->ptrs[i] = kmalloc_node(size, GFP_KERNEL, node);
+		else
+			pdata->ptrs[i] = kmalloc(size, GFP_KERNEL);
+
+		if (!pdata->ptrs[i])
+			goto unwind_oom;
+		memset(pdata->ptrs[i], 0, size);
+	}
+
+	/* Catch derefs w/o wrappers */
+	return (void *)(~(unsigned long)pdata);
+
+unwind_oom:
+	while (--i >= 0) {
+		if (!cpu_possible(i))
+			continue;
+		kfree(pdata->ptrs[i]);
+	}
+	kfree(pdata);
+	return NULL;
+}
+EXPORT_SYMBOL(__alloc_percpu);
+
+/**
+ * free_percpu - free previously allocated percpu memory
+ * @objp: pointer returned by alloc_percpu.
+ *
+ * Don't free memory not originally allocated by alloc_percpu()
+ * The complemented objp is to check for that.
+ */
+void free_percpu(const void *objp)
+{
+	int i;
+	struct percpu_data *p = (struct percpu_data *)(~(unsigned long)objp);
+
+	/*
+	 * We allocate for all cpus so we cannot use for online cpu here.
+	 */
+	for_each_possible_cpu(i)
+	    kfree(p->ptrs[i]);
+	kfree(p);
+}
+EXPORT_SYMBOL(free_percpu);
+
Index: linux-2.6.18-rc4/mm/Makefile
===================================================================
--- linux-2.6.18-rc4.orig/mm/Makefile	2006-08-06 11:20:11.000000000 -0700
+++ linux-2.6.18-rc4/mm/Makefile	2006-08-18 20:57:49.844452865 -0700
@@ -13,6 +13,7 @@ obj-y			:= bootmem.o filemap.o mempool.o
 			   prio_tree.o util.o mmzone.o vmstat.o $(mmu-y)
 
 obj-$(CONFIG_SWAP)	+= page_io.o swap_state.o swapfile.o thrash.o
+obj-$(CONFIG_SMP)	+= allocpercpu.o
 obj-$(CONFIG_HUGETLBFS)	+= hugetlb.o
 obj-$(CONFIG_NUMA) 	+= mempolicy.o
 obj-$(CONFIG_SPARSEMEM)	+= sparse.o
Index: linux-2.6.18-rc4/mm/slab.c
===================================================================
--- linux-2.6.18-rc4.orig/mm/slab.c	2006-08-06 11:20:11.000000000 -0700
+++ linux-2.6.18-rc4/mm/slab.c	2006-08-18 20:57:49.858123897 -0700
@@ -3370,55 +3370,6 @@ void *__kmalloc_track_caller(size_t size
 EXPORT_SYMBOL(__kmalloc_track_caller);
 #endif
 
-#ifdef CONFIG_SMP
-/**
- * __alloc_percpu - allocate one copy of the object for every present
- * cpu in the system, zeroing them.
- * Objects should be dereferenced using the per_cpu_ptr macro only.
- *
- * @size: how many bytes of memory are required.
- */
-void *__alloc_percpu(size_t size)
-{
-	int i;
-	struct percpu_data *pdata = kmalloc(sizeof(*pdata), GFP_KERNEL);
-
-	if (!pdata)
-		return NULL;
-
-	/*
-	 * Cannot use for_each_online_cpu since a cpu may come online
-	 * and we have no way of figuring out how to fix the array
-	 * that we have allocated then....
-	 */
-	for_each_possible_cpu(i) {
-		int node = cpu_to_node(i);
-
-		if (node_online(node))
-			pdata->ptrs[i] = kmalloc_node(size, GFP_KERNEL, node);
-		else
-			pdata->ptrs[i] = kmalloc(size, GFP_KERNEL);
-
-		if (!pdata->ptrs[i])
-			goto unwind_oom;
-		memset(pdata->ptrs[i], 0, size);
-	}
-
-	/* Catch derefs w/o wrappers */
-	return (void *)(~(unsigned long)pdata);
-
-unwind_oom:
-	while (--i >= 0) {
-		if (!cpu_possible(i))
-			continue;
-		kfree(pdata->ptrs[i]);
-	}
-	kfree(pdata);
-	return NULL;
-}
-EXPORT_SYMBOL(__alloc_percpu);
-#endif
-
 /**
  * kmem_cache_free - Deallocate an object
  * @cachep: The cache the allocation was from.
@@ -3464,29 +3415,6 @@ void kfree(const void *objp)
 }
 EXPORT_SYMBOL(kfree);
 
-#ifdef CONFIG_SMP
-/**
- * free_percpu - free previously allocated percpu memory
- * @objp: pointer returned by alloc_percpu.
- *
- * Don't free memory not originally allocated by alloc_percpu()
- * The complemented objp is to check for that.
- */
-void free_percpu(const void *objp)
-{
-	int i;
-	struct percpu_data *p = (struct percpu_data *)(~(unsigned long)objp);
-
-	/*
-	 * We allocate for all cpus so we cannot use for online cpu here.
-	 */
-	for_each_possible_cpu(i)
-	    kfree(p->ptrs[i]);
-	kfree(p);
-}
-EXPORT_SYMBOL(free_percpu);
-#endif
-
 unsigned int kmem_cache_size(struct kmem_cache *cachep)
 {
 	return obj_size(cachep);
Index: linux-2.6.18-rc4/mm/slob.c
===================================================================
--- linux-2.6.18-rc4.orig/mm/slob.c	2006-08-06 11:20:11.000000000 -0700
+++ linux-2.6.18-rc4/mm/slob.c	2006-08-18 20:57:49.859100399 -0700
@@ -343,48 +343,3 @@ void kmem_cache_init(void)
 atomic_t slab_reclaim_pages = ATOMIC_INIT(0);
 EXPORT_SYMBOL(slab_reclaim_pages);
 
-#ifdef CONFIG_SMP
-
-void *__alloc_percpu(size_t size)
-{
-	int i;
-	struct percpu_data *pdata = kmalloc(sizeof (*pdata), GFP_KERNEL);
-
-	if (!pdata)
-		return NULL;
-
-	for_each_possible_cpu(i) {
-		pdata->ptrs[i] = kmalloc(size, GFP_KERNEL);
-		if (!pdata->ptrs[i])
-			goto unwind_oom;
-		memset(pdata->ptrs[i], 0, size);
-	}
-
-	/* Catch derefs w/o wrappers */
-	return (void *) (~(unsigned long) pdata);
-
-unwind_oom:
-	while (--i >= 0) {
-		if (!cpu_possible(i))
-			continue;
-		kfree(pdata->ptrs[i]);
-	}
-	kfree(pdata);
-	return NULL;
-}
-EXPORT_SYMBOL(__alloc_percpu);
-
-void
-free_percpu(const void *objp)
-{
-	int i;
-	struct percpu_data *p = (struct percpu_data *) (~(unsigned long) objp);
-
-	for_each_possible_cpu(i)
-		kfree(p->ptrs[i]);
-
-	kfree(p);
-}
-EXPORT_SYMBOL(free_percpu);
-
-#endif

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Re: [PATCH] Extract the allocpercpu functions from the slab allocator

[Matt Mackall]

On Fri, Aug 18, 2006 at 09:14:06PM -0700, Christoph Lameter wrote:
> The allocpercpu functions __alloc_percpu and __free_percpu() are heavily 
> using the slab allocator. However, they are conceptually different 
> allocators that can be used independently from the slab. Currently the 
> slab code is duplicated in slob. This patch also 
> simplifies SLOB.
> 
> Signed-off-by: Christoph Lameter <clameter@sgi.com>

Nice.

Signed-off-by: Matt Mackall <mpm@selenic.com>

-- 
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Re: [PATCH] Extract the allocpercpu functions from the slab allocator

[Andrew Morton]

On Fri, 18 Aug 2006 21:14:06 -0700 (PDT)
Christoph Lameter <clameter@sgi.com> wrote:

> The allocpercpu functions __alloc_percpu and __free_percpu() are heavily 
> using the slab allocator.

These functions don't exist since cpu-hotplug-compatible-alloc_percpu.patch.

Can you please see whether this cleanup is applicable to -mm?

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Re: [PATCH] Extract the allocpercpu functions from the slab allocator

[Christoph Lameter]

On Fri, 18 Aug 2006, Andrew Morton wrote:

> On Fri, 18 Aug 2006 21:14:06 -0700 (PDT)
> Christoph Lameter <clameter@sgi.com> wrote:
> 
> > The allocpercpu functions __alloc_percpu and __free_percpu() are heavily 
> > using the slab allocator.
> 
> These functions don't exist since cpu-hotplug-compatible-alloc_percpu.patch.
> 
> Can you please see whether this cleanup is applicable to -mm?

Here is the earlier patch for 2.6.18-rc4-mm2:


Separate the allocpercpu functions from the slab allocator

The allocpercpu functions __alloc_percpu and __free_percpu() are
heavily using the slab allocator. However, they are conceptually
different allocators that can be used independently from the
slab. This also simplifies SLOB (at this point slob may
be broken in mm. This should fix it).

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.18-rc4-mm2/mm/allocpercpu.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.18-rc4-mm2/mm/allocpercpu.c	2006-08-23 12:32:06.928511026 -0700
@@ -0,0 +1,130 @@
+/*
+ * linux/mm/allocpercpu.c
+ *
+ * Separated out from slab.c August 11, 2006 Christoph Lameter <clameter@sgi.com>
+ */
+#include <linux/mm.h>
+#include <linux/module.h>
+
+/**
+ * percpu_depopulate - depopulate per-cpu data for given cpu
+ * @__pdata: per-cpu data to depopulate
+ * @cpu: depopulate per-cpu data for this cpu
+ *
+ * Depopulating per-cpu data for a cpu going offline would be a typical
+ * use case. You need to register a cpu hotplug handler for that purpose.
+ */
+void percpu_depopulate(void *__pdata, int cpu)
+{
+	struct percpu_data *pdata = __percpu_disguise(__pdata);
+	if (pdata->ptrs[cpu]) {
+		kfree(pdata->ptrs[cpu]);
+		pdata->ptrs[cpu] = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(percpu_depopulate);
+
+/**
+ * percpu_depopulate_mask - depopulate per-cpu data for some cpu's
+ * @__pdata: per-cpu data to depopulate
+ * @mask: depopulate per-cpu data for cpu's selected through mask bits
+ */
+void __percpu_depopulate_mask(void *__pdata, cpumask_t *mask)
+{
+	int cpu;
+	for_each_cpu_mask(cpu, *mask)
+		percpu_depopulate(__pdata, cpu);
+}
+EXPORT_SYMBOL_GPL(__percpu_depopulate_mask);
+
+/**
+ * percpu_populate - populate per-cpu data for given cpu
+ * @__pdata: per-cpu data to populate further
+ * @size: size of per-cpu object
+ * @gfp: may sleep or not etc.
+ * @cpu: populate per-data for this cpu
+ *
+ * Populating per-cpu data for a cpu coming online would be a typical
+ * use case. You need to register a cpu hotplug handler for that purpose.
+ * Per-cpu object is populated with zeroed buffer.
+ */
+void *percpu_populate(void *__pdata, size_t size, gfp_t gfp, int cpu)
+{
+	struct percpu_data *pdata = __percpu_disguise(__pdata);
+	int node = cpu_to_node(cpu);
+
+	BUG_ON(pdata->ptrs[cpu]);
+	if (node_online(node)) {
+		/* FIXME: kzalloc_node(size, gfp, node) */
+		pdata->ptrs[cpu] = kmalloc_node(size, gfp, node);
+		if (pdata->ptrs[cpu])
+			memset(pdata->ptrs[cpu], 0, size);
+	} else
+		pdata->ptrs[cpu] = kzalloc(size, gfp);
+	return pdata->ptrs[cpu];
+}
+EXPORT_SYMBOL_GPL(percpu_populate);
+
+/**
+ * percpu_populate_mask - populate per-cpu data for more cpu's
+ * @__pdata: per-cpu data to populate further
+ * @size: size of per-cpu object
+ * @gfp: may sleep or not etc.
+ * @mask: populate per-cpu data for cpu's selected through mask bits
+ *
+ * Per-cpu objects are populated with zeroed buffers.
+ */
+int __percpu_populate_mask(void *__pdata, size_t size, gfp_t gfp,
+			   cpumask_t *mask)
+{
+	cpumask_t populated = CPU_MASK_NONE;
+	int cpu;
+
+	for_each_cpu_mask(cpu, *mask)
+		if (unlikely(!percpu_populate(__pdata, size, gfp, cpu))) {
+			__percpu_depopulate_mask(__pdata, &populated);
+			return -ENOMEM;
+		} else
+			cpu_set(cpu, populated);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__percpu_populate_mask);
+
+/**
+ * percpu_alloc_mask - initial setup of per-cpu data
+ * @size: size of per-cpu object
+ * @gfp: may sleep or not etc.
+ * @mask: populate per-data for cpu's selected through mask bits
+ *
+ * Populating per-cpu data for all online cpu's would be a typical use case,
+ * which is simplified by the percpu_alloc() wrapper.
+ * Per-cpu objects are populated with zeroed buffers.
+ */
+void *__percpu_alloc_mask(size_t size, gfp_t gfp, cpumask_t *mask)
+{
+	void *pdata = kzalloc(sizeof(struct percpu_data), gfp);
+	void *__pdata = __percpu_disguise(pdata);
+
+	if (unlikely(!pdata))
+		return NULL;
+	if (likely(!__percpu_populate_mask(__pdata, size, gfp, mask)))
+		return __pdata;
+	kfree(pdata);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(__percpu_alloc_mask);
+
+/**
+ * percpu_free - final cleanup of per-cpu data
+ * @__pdata: object to clean up
+ *
+ * We simply clean up any per-cpu object left. No need for the client to
+ * track and specify through a bis mask which per-cpu objects are to free.
+ */
+void percpu_free(void *__pdata)
+{
+	__percpu_depopulate_mask(__pdata, &cpu_possible_map);
+	kfree(__percpu_disguise(__pdata));
+}
+EXPORT_SYMBOL_GPL(percpu_free);
+
Index: linux-2.6.18-rc4-mm2/mm/slab.c
===================================================================
--- linux-2.6.18-rc4-mm2.orig/mm/slab.c	2006-08-20 16:17:35.371551737 -0700
+++ linux-2.6.18-rc4-mm2/mm/slab.c	2006-08-23 12:16:44.728638839 -0700
@@ -3464,130 +3464,6 @@ void *__kmalloc_track_caller(size_t size
 EXPORT_SYMBOL(__kmalloc_track_caller);
 #endif
 
-#ifdef CONFIG_SMP
-/**
- * percpu_depopulate - depopulate per-cpu data for given cpu
- * @__pdata: per-cpu data to depopulate
- * @cpu: depopulate per-cpu data for this cpu
- *
- * Depopulating per-cpu data for a cpu going offline would be a typical
- * use case. You need to register a cpu hotplug handler for that purpose.
- */
-void percpu_depopulate(void *__pdata, int cpu)
-{
-	struct percpu_data *pdata = __percpu_disguise(__pdata);
-	if (pdata->ptrs[cpu]) {
-		kfree(pdata->ptrs[cpu]);
-		pdata->ptrs[cpu] = NULL;
-	}
-}
-EXPORT_SYMBOL_GPL(percpu_depopulate);
-
-/**
- * percpu_depopulate_mask - depopulate per-cpu data for some cpu's
- * @__pdata: per-cpu data to depopulate
- * @mask: depopulate per-cpu data for cpu's selected through mask bits
- */
-void __percpu_depopulate_mask(void *__pdata, cpumask_t *mask)
-{
-	int cpu;
-	for_each_cpu_mask(cpu, *mask)
-		percpu_depopulate(__pdata, cpu);
-}
-EXPORT_SYMBOL_GPL(__percpu_depopulate_mask);
-
-/**
- * percpu_populate - populate per-cpu data for given cpu
- * @__pdata: per-cpu data to populate further
- * @size: size of per-cpu object
- * @gfp: may sleep or not etc.
- * @cpu: populate per-data for this cpu
- *
- * Populating per-cpu data for a cpu coming online would be a typical
- * use case. You need to register a cpu hotplug handler for that purpose.
- * Per-cpu object is populated with zeroed buffer.
- */
-void *percpu_populate(void *__pdata, size_t size, gfp_t gfp, int cpu)
-{
-	struct percpu_data *pdata = __percpu_disguise(__pdata);
-	int node = cpu_to_node(cpu);
-
-	BUG_ON(pdata->ptrs[cpu]);
-	if (node_online(node)) {
-		/* FIXME: kzalloc_node(size, gfp, node) */
-		pdata->ptrs[cpu] = kmalloc_node(size, gfp, node);
-		if (pdata->ptrs[cpu])
-			memset(pdata->ptrs[cpu], 0, size);
-	} else
-		pdata->ptrs[cpu] = kzalloc(size, gfp);
-	return pdata->ptrs[cpu];
-}
-EXPORT_SYMBOL_GPL(percpu_populate);
-
-/**
- * percpu_populate_mask - populate per-cpu data for more cpu's
- * @__pdata: per-cpu data to populate further
- * @size: size of per-cpu object
- * @gfp: may sleep or not etc.
- * @mask: populate per-cpu data for cpu's selected through mask bits
- *
- * Per-cpu objects are populated with zeroed buffers.
- */
-int __percpu_populate_mask(void *__pdata, size_t size, gfp_t gfp,
-			   cpumask_t *mask)
-{
-	cpumask_t populated = CPU_MASK_NONE;
-	int cpu;
-
-	for_each_cpu_mask(cpu, *mask)
-		if (unlikely(!percpu_populate(__pdata, size, gfp, cpu))) {
-			__percpu_depopulate_mask(__pdata, &populated);
-			return -ENOMEM;
-		} else
-			cpu_set(cpu, populated);
-	return 0;
-}
-EXPORT_SYMBOL_GPL(__percpu_populate_mask);
-
-/**
- * percpu_alloc_mask - initial setup of per-cpu data
- * @size: size of per-cpu object
- * @gfp: may sleep or not etc.
- * @mask: populate per-data for cpu's selected through mask bits
- *
- * Populating per-cpu data for all online cpu's would be a typical use case,
- * which is simplified by the percpu_alloc() wrapper.
- * Per-cpu objects are populated with zeroed buffers.
- */
-void *__percpu_alloc_mask(size_t size, gfp_t gfp, cpumask_t *mask)
-{
-	void *pdata = kzalloc(sizeof(struct percpu_data), gfp);
-	void *__pdata = __percpu_disguise(pdata);
-
-	if (unlikely(!pdata))
-		return NULL;
-	if (likely(!__percpu_populate_mask(__pdata, size, gfp, mask)))
-		return __pdata;
-	kfree(pdata);
-	return NULL;
-}
-EXPORT_SYMBOL_GPL(__percpu_alloc_mask);
-
-/**
- * percpu_free - final cleanup of per-cpu data
- * @__pdata: object to clean up
- *
- * We simply clean up any per-cpu object left. No need for the client to
- * track and specify through a bis mask which per-cpu objects are to free.
- */
-void percpu_free(void *__pdata)
-{
-	__percpu_depopulate_mask(__pdata, &cpu_possible_map);
-	kfree(__percpu_disguise(__pdata));
-}
-EXPORT_SYMBOL_GPL(percpu_free);
-#endif	/* CONFIG_SMP */
-
 /**
  * kmem_cache_free - Deallocate an object
  * @cachep: The cache the allocation was from.
Index: linux-2.6.18-rc4-mm2/mm/slob.c
===================================================================
--- linux-2.6.18-rc4-mm2.orig/mm/slob.c	2006-08-06 11:20:11.000000000 -0700
+++ linux-2.6.18-rc4-mm2/mm/slob.c	2006-08-23 12:15:47.263435113 -0700
@@ -343,48 +343,3 @@ void kmem_cache_init(void)
 atomic_t slab_reclaim_pages = ATOMIC_INIT(0);
 EXPORT_SYMBOL(slab_reclaim_pages);
 
-#ifdef CONFIG_SMP
-
-void *__alloc_percpu(size_t size)
-{
-	int i;
-	struct percpu_data *pdata = kmalloc(sizeof (*pdata), GFP_KERNEL);
-
-	if (!pdata)
-		return NULL;
-
-	for_each_possible_cpu(i) {
-		pdata->ptrs[i] = kmalloc(size, GFP_KERNEL);
-		if (!pdata->ptrs[i])
-			goto unwind_oom;
-		memset(pdata->ptrs[i], 0, size);
-	}
-
-	/* Catch derefs w/o wrappers */
-	return (void *) (~(unsigned long) pdata);
-
-unwind_oom:
-	while (--i >= 0) {
-		if (!cpu_possible(i))
-			continue;
-		kfree(pdata->ptrs[i]);
-	}
-	kfree(pdata);
-	return NULL;
-}
-EXPORT_SYMBOL(__alloc_percpu);
-
-void
-free_percpu(const void *objp)
-{
-	int i;
-	struct percpu_data *p = (struct percpu_data *) (~(unsigned long) objp);
-
-	for_each_possible_cpu(i)
-		kfree(p->ptrs[i]);
-
-	kfree(p);
-}
-EXPORT_SYMBOL(free_percpu);
-
-#endif
Index: linux-2.6.18-rc4-mm2/mm/Makefile
===================================================================
--- linux-2.6.18-rc4-mm2.orig/mm/Makefile	2006-08-20 16:17:35.290502052 -0700
+++ linux-2.6.18-rc4-mm2/mm/Makefile	2006-08-23 12:31:02.784040263 -0700
@@ -24,4 +24,5 @@ obj-$(CONFIG_SLAB) += slab.o
 obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
 obj-$(CONFIG_FS_XIP) += filemap_xip.o
 obj-$(CONFIG_MIGRATION) += migrate.o
+obj-$(CONFIG_SMP) += allocpercpu.o
 
 

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