[PATCH -mm] relayfs: support larger relay buffer

[PATCH -mm] relayfs: support larger relay buffer

[Masami Hiramatsu]

Use vmalloc() and memset() instead of kcalloc() to allocate a page* array
when the array size is bigger than one page. This enables relayfs to support
bigger relay buffers than 64MB on 4k-page system, 512MB on 16k-page system.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
---
This is useful for a 64-bit system which has a plenty of memory (tens of
giga bytes) and a large kernel memory space.

I tested it on x86-64 and ia64.

 kernel/relay.c |   22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

Index: 2.6.25-rc8-mm2/kernel/relay.c
===================================================================
--- 2.6.25-rc8-mm2.orig/kernel/relay.c
+++ 2.6.25-rc8-mm2/kernel/relay.c
@@ -104,12 +104,20 @@ static int relay_mmap_buf(struct rchan_b
 static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size)
 {
 	void *mem;
-	unsigned int i, j, n_pages;
+	unsigned int i, j, n_pages, pa_size;

 	*size = PAGE_ALIGN(*size);
 	n_pages = *size >> PAGE_SHIFT;
+	pa_size = n_pages * sizeof(struct page *);

-	buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
+	if (pa_size > PAGE_SIZE) {
+		buf->page_array = vmalloc(pa_size);
+		if (buf->page_array)
+			memset(buf->page_array, 0, pa_size);
+	} else {
+		buf->page_array = kcalloc(n_pages, sizeof(struct page *),
+					  GFP_KERNEL);
+	}
 	if (!buf->page_array)
 		return NULL;

@@ -130,7 +138,10 @@ static void *relay_alloc_buf(struct rcha
 depopulate:
 	for (j = 0; j < i; j++)
 		__free_page(buf->page_array[j]);
-	kfree(buf->page_array);
+	if (pa_size > PAGE_SIZE)
+		vfree(buf->page_array);
+	else
+		kfree(buf->page_array);
 	return NULL;
 }

@@ -189,7 +200,10 @@ static void relay_destroy_buf(struct rch
 		vunmap(buf->start);
 		for (i = 0; i < buf->page_count; i++)
 			__free_page(buf->page_array[i]);
-		kfree(buf->page_array);
+		if (buf->page_count * sizeof(struct page *) > PAGE_SIZE)
+			vfree(buf->page_array);
+		else
+			kfree(buf->page_array);
 	}
 	chan->buf[buf->cpu] = NULL;
 	kfree(buf->padding);
-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH -mm] relayfs: support larger relay buffer

[Tom Zanussi]

On Tue, 2008-04-15 at 11:27 -0400, Masami Hiramatsu wrote:
> Use vmalloc() and memset() instead of kcalloc() to allocate a page* array
> when the array size is bigger than one page. This enables relayfs to support
> bigger relay buffers than 64MB on 4k-page system, 512MB on 16k-page system.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> ---
> This is useful for a 64-bit system which has a plenty of memory (tens of
> giga bytes) and a large kernel memory space.
> 
> I tested it on x86-64 and ia64.
> 

Hi,

It looks ok to me, but it might be a little cleaner and avoid some
duplication if you add the new code as a couple of functions instead.
Just a suggestion...

Tom

>  kernel/relay.c |   22 ++++++++++++++++++----
>  1 file changed, 18 insertions(+), 4 deletions(-)
> 
> Index: 2.6.25-rc8-mm2/kernel/relay.c
> ===================================================================
> --- 2.6.25-rc8-mm2.orig/kernel/relay.c
> +++ 2.6.25-rc8-mm2/kernel/relay.c
> @@ -104,12 +104,20 @@ static int relay_mmap_buf(struct rchan_b
>  static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size)
>  {
>  	void *mem;
> -	unsigned int i, j, n_pages;
> +	unsigned int i, j, n_pages, pa_size;
> 
>  	*size = PAGE_ALIGN(*size);
>  	n_pages = *size >> PAGE_SHIFT;
> +	pa_size = n_pages * sizeof(struct page *);
> 
> -	buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
> +	if (pa_size > PAGE_SIZE) {
> +		buf->page_array = vmalloc(pa_size);
> +		if (buf->page_array)
> +			memset(buf->page_array, 0, pa_size);
> +	} else {
> +		buf->page_array = kcalloc(n_pages, sizeof(struct page *),
> +					  GFP_KERNEL);
> +	}
>  	if (!buf->page_array)
>  		return NULL;
> 
> @@ -130,7 +138,10 @@ static void *relay_alloc_buf(struct rcha
>  depopulate:
>  	for (j = 0; j < i; j++)
>  		__free_page(buf->page_array[j]);
> -	kfree(buf->page_array);
> +	if (pa_size > PAGE_SIZE)
> +		vfree(buf->page_array);
> +	else
> +		kfree(buf->page_array);
>  	return NULL;
>  }
> 
> @@ -189,7 +200,10 @@ static void relay_destroy_buf(struct rch
>  		vunmap(buf->start);
>  		for (i = 0; i < buf->page_count; i++)
>  			__free_page(buf->page_array[i]);
> -		kfree(buf->page_array);
> +		if (buf->page_count * sizeof(struct page *) > PAGE_SIZE)
> +			vfree(buf->page_array);
> +		else
> +			kfree(buf->page_array);
>  	}
>  	chan->buf[buf->cpu] = NULL;
>  	kfree(buf->padding);

Re: [PATCH -mm] relayfs: support larger relay buffer

[Masami Hiramatsu]

Hi Tom,

Tom Zanussi wrote:
> On Tue, 2008-04-15 at 11:27 -0400, Masami Hiramatsu wrote:
>> Use vmalloc() and memset() instead of kcalloc() to allocate a page* array
>> when the array size is bigger than one page. This enables relayfs to support
>> bigger relay buffers than 64MB on 4k-page system, 512MB on 16k-page system.
>>
>> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
>> ---
>> This is useful for a 64-bit system which has a plenty of memory (tens of
>> giga bytes) and a large kernel memory space.
>>
>> I tested it on x86-64 and ia64.
>>
> 
> Hi,
> 
> It looks ok to me, but it might be a little cleaner and avoid some
> duplication if you add the new code as a couple of functions instead.
> Just a suggestion...

Sure, that is a good idea, I'll renew my patch.
Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

[PATCH -mm] relayfs: support larger relay buffer take 2

[Masami Hiramatsu]

Use vmalloc() and memset() instead of kcalloc() to allocate a page* array
when the array size is bigger than one page. This enables relayfs to support
bigger relay buffers than 64MB on 4k-page system, 512MB on 16k-page system.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
---
Changes from take1 to take2:
- add relay_alloc_page_array() and relay_free_page_array()
- use is_vmalloc_addr() instead of checking array size.

This is useful for a 64-bit system which has a plenty of memory (tens of
giga bytes) and a large kernel memory space.

I tested it on x86-64 and ia64.

 kernel/relay.c |   29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

Index: 2.6.25-rc8-mm2/kernel/relay.c
===================================================================
--- 2.6.25-rc8-mm2.orig/kernel/relay.c
+++ 2.6.25-rc8-mm2/kernel/relay.c
@@ -27,6 +27,29 @@
 static DEFINE_MUTEX(relay_channels_mutex);
 static LIST_HEAD(relay_channels);

+static struct page *relay_alloc_page_array(unsigned int n_pages)
+{
+	struct page *array;
+	unsigned int pa_size = n_pages * sizeof(struct page *);
+
+	if (pa_size > PAGE_SIZE) {
+		array = vmalloc(pa_size);
+		if (array)
+			memset(array, 0, pa_size);
+	} else {
+		array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
+	}
+	return array;
+}
+
+static void relay_free_page_array(struct page *array)
+{
+	if (is_vmalloc_addr(array))
+		vfree(array);
+	else
+		kfree(array);
+}
+
 /*
  * close() vm_op implementation for relay file mapping.
  */
@@ -109,7 +132,7 @@ static void *relay_alloc_buf(struct rcha
 	*size = PAGE_ALIGN(*size);
 	n_pages = *size >> PAGE_SHIFT;

-	buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
+	buf->page_array = relay_alloc_page_array(n_pages);
 	if (!buf->page_array)
 		return NULL;

@@ -130,7 +153,7 @@ static void *relay_alloc_buf(struct rcha
 depopulate:
 	for (j = 0; j < i; j++)
 		__free_page(buf->page_array[j]);
-	kfree(buf->page_array);
+	relay_free_page_array(buf->page_array);
 	return NULL;
 }

@@ -189,7 +212,7 @@ static void relay_destroy_buf(struct rch
 		vunmap(buf->start);
 		for (i = 0; i < buf->page_count; i++)
 			__free_page(buf->page_array[i]);
-		kfree(buf->page_array);
+		relay_free_page_array(buf->page_array);
 	}
 	chan->buf[buf->cpu] = NULL;
 	kfree(buf->padding);

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH -mm] relayfs: support larger relay buffer take 2

[Pekka J Enberg]

Hi Masami,

On Wed, 16 Apr 2008, Masami Hiramatsu wrote:
> +static struct page *relay_alloc_page_array(unsigned int n_pages)
> +{
> +	struct page *array;
> +	unsigned int pa_size = n_pages * sizeof(struct page *);
> +
> +	if (pa_size > PAGE_SIZE) {
> +		array = vmalloc(pa_size);
> +		if (array)
> +			memset(array, 0, pa_size);
> +	} else {
> +		array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
> +	}
> +	return array;
> +}

I think it's bit confusing to have relay_alloc_page_array() return a 
pointer to struct page as it's really allocating an _array_ of pointers to 
struct page. So why not just use void * here as the kernel memory 
allocators do?

> +static void relay_free_page_array(struct page *array)
> +{
> +	if (is_vmalloc_addr(array))
> +		vfree(array);
> +	else
> +		kfree(array);
> +}

Here as well.

Re: [PATCH -mm] relayfs: support larger relay buffer take 2

[Masami Hiramatsu]

Hi,

Pekka J Enberg wrote:
> Hi Masami,
> 
> On Wed, 16 Apr 2008, Masami Hiramatsu wrote:
>> +static struct page *relay_alloc_page_array(unsigned int n_pages)
>> +{
>> +	struct page *array;
>> +	unsigned int pa_size = n_pages * sizeof(struct page *);
>> +
>> +	if (pa_size > PAGE_SIZE) {
>> +		array = vmalloc(pa_size);
>> +		if (array)
>> +			memset(array, 0, pa_size);
>> +	} else {
>> +		array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
>> +	}
>> +	return array;
>> +}
> 
> I think it's bit confusing to have relay_alloc_page_array() return a 
> pointer to struct page as it's really allocating an _array_ of pointers to 
> struct page. So why not just use void * here as the kernel memory 
> allocators do?

Thank you very much, it was my mistake.
It should return struct page **.

>> +static void relay_free_page_array(struct page *array)
>> +{
>> +	if (is_vmalloc_addr(array))
>> +		vfree(array);
>> +	else
>> +		kfree(array);
>> +}
> 
> Here as well.

Thanks,


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

[PATCH -mm] relayfs: support larger relay buffer take 3

[Masami Hiramatsu]

Use vmalloc() and memset() instead of kcalloc() to allocate a page* array
when the array size is bigger than one page. This enables relayfs to support
bigger relay buffers than 64MB on 4k-page system, 512MB on 16k-page system.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
---
Changes from take2 to take3:
 - Use struct page ** instead of struct page *.
 - move functions to the place before relay_mmap_buf.
 - add comments.

This is useful for a 64-bit system which has a plenty of memory (tens of
giga bytes) and a large kernel memory space.

I tested it on x86-64 and ia64.

 kernel/relay.c |   35 ++++++++++++++++++++++++++++++++---
 1 file changed, 32 insertions(+), 3 deletions(-)

Index: 2.6.25-rc8-mm2/kernel/relay.c
===================================================================
--- 2.6.25-rc8-mm2.orig/kernel/relay.c
+++ 2.6.25-rc8-mm2/kernel/relay.c
@@ -65,6 +65,35 @@ static struct vm_operations_struct relay
 	.close = relay_file_mmap_close,
 };

+/*
+ * allocate an array of pointers of struct page
+ */
+static struct page **relay_alloc_page_array(unsigned int n_pages)
+{
+	struct page **array;
+	unsigned int pa_size = n_pages * sizeof(struct page *);
+
+	if (pa_size > PAGE_SIZE) {
+		array = vmalloc(pa_size);
+		if (array)
+			memset(array, 0, pa_size);
+	} else {
+		array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
+	}
+	return array;
+}
+
+/*
+ * free an array of pointers of struct page
+ */
+static void relay_free_page_array(struct page **array)
+{
+	if (is_vmalloc_addr(array))
+		vfree(array);
+	else
+		kfree(array);
+}
+
 /**
  *	relay_mmap_buf: - mmap channel buffer to process address space
  *	@buf: relay channel buffer
@@ -109,7 +138,7 @@ static void *relay_alloc_buf(struct rcha
 	*size = PAGE_ALIGN(*size);
 	n_pages = *size >> PAGE_SHIFT;

-	buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
+	buf->page_array = relay_alloc_page_array(n_pages);
 	if (!buf->page_array)
 		return NULL;

@@ -130,7 +159,7 @@ static void *relay_alloc_buf(struct rcha
 depopulate:
 	for (j = 0; j < i; j++)
 		__free_page(buf->page_array[j]);
-	kfree(buf->page_array);
+	relay_free_page_array(buf->page_array);
 	return NULL;
 }

@@ -189,7 +218,7 @@ static void relay_destroy_buf(struct rch
 		vunmap(buf->start);
 		for (i = 0; i < buf->page_count; i++)
 			__free_page(buf->page_array[i]);
-		kfree(buf->page_array);
+		relay_free_page_array(buf->page_array);
 	}
 	chan->buf[buf->cpu] = NULL;
 	kfree(buf->padding);
-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH -mm] relayfs: support larger relay buffer take 3

[Pekka Enberg]

Masami Hiramatsu wrote:
> Use vmalloc() and memset() instead of kcalloc() to allocate a page* array
> when the array size is bigger than one page. This enables relayfs to support
> bigger relay buffers than 64MB on 4k-page system, 512MB on 16k-page system.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>

Looks good to me!

Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>

Re: [PATCH -mm] relayfs: support larger relay buffer take 3

[Andrew Morton]

On Wed, 16 Apr 2008 15:51:56 -0400
Masami Hiramatsu <mhiramat@redhat.com> wrote:

> +static struct page **relay_alloc_page_array(unsigned int n_pages)
> +{
> +	struct page **array;
> +	unsigned int pa_size = n_pages * sizeof(struct page *);
> +
> +	if (pa_size > PAGE_SIZE) {
> +		array = vmalloc(pa_size);
> +		if (array)
> +			memset(array, 0, pa_size);
> +	} else {
> +		array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
> +	}
> +	return array;
> +}

It's a bit odd to multiply n_pages*sizeof() and to then call kcalloc(),
which needs to do the same multiplication.

The compiler will presumably optimise that away, but still, how about this?

--- a/kernel/relay.c~relayfs-support-larger-relay-buffer-take-3-cleanup
+++ a/kernel/relay.c
@@ -71,14 +71,14 @@ static struct vm_operations_struct relay
 static struct page **relay_alloc_page_array(unsigned int n_pages)
 {
 	struct page **array;
-	unsigned int pa_size = n_pages * sizeof(struct page *);
+	size_t pa_size = n_pages * sizeof(struct page *);
 
 	if (pa_size > PAGE_SIZE) {
 		array = vmalloc(pa_size);
 		if (array)
 			memset(array, 0, pa_size);
 	} else {
-		array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
+		array = kzalloc(pa_size, GFP_KERNEL);
 	}
 	return array;
 }
_


size_t is strictly the correct type for pa_size here.  Even though
vmalloc() takes a ulong.

Re: [PATCH -mm] relayfs: support larger relay buffer take 3

[Masami Hiramatsu]

Hi Andrew,

Andrew Morton wrote:
> On Wed, 16 Apr 2008 15:51:56 -0400
> Masami Hiramatsu <mhiramat@redhat.com> wrote:
> 
>> +static struct page **relay_alloc_page_array(unsigned int n_pages)
>> +{
>> +	struct page **array;
>> +	unsigned int pa_size = n_pages * sizeof(struct page *);
>> +
>> +	if (pa_size > PAGE_SIZE) {
>> +		array = vmalloc(pa_size);
>> +		if (array)
>> +			memset(array, 0, pa_size);
>> +	} else {
>> +		array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
>> +	}
>> +	return array;
>> +}
> 
> It's a bit odd to multiply n_pages*sizeof() and to then call kcalloc(),
> which needs to do the same multiplication.
> 
> The compiler will presumably optimise that away, but still, how about this?

Sure, it looks good to me.
Thank you so much,

Acked-by: Masami Hiramatsu <mhiramat@redhat.com>

> 
> --- a/kernel/relay.c~relayfs-support-larger-relay-buffer-take-3-cleanup
> +++ a/kernel/relay.c
> @@ -71,14 +71,14 @@ static struct vm_operations_struct relay
>  static struct page **relay_alloc_page_array(unsigned int n_pages)
>  {
>  	struct page **array;
> -	unsigned int pa_size = n_pages * sizeof(struct page *);
> +	size_t pa_size = n_pages * sizeof(struct page *);
>  
>  	if (pa_size > PAGE_SIZE) {
>  		array = vmalloc(pa_size);
>  		if (array)
>  			memset(array, 0, pa_size);
>  	} else {
> -		array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
> +		array = kzalloc(pa_size, GFP_KERNEL);
>  	}
>  	return array;
>  }
> _
> 
> 
> size_t is strictly the correct type for pa_size here.  Even though
> vmalloc() takes a ulong.

Thanks for the advice,


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH -mm] relayfs: support larger relay buffer take 3

[Tom Zanussi]

On Wed, 2008-04-16 at 15:51 -0400, Masami Hiramatsu wrote:
> Use vmalloc() and memset() instead of kcalloc() to allocate a page* array
> when the array size is bigger than one page. This enables relayfs to support
> bigger relay buffers than 64MB on 4k-page system, 512MB on 16k-page system.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> ---
> Changes from take2 to take3:
>  - Use struct page ** instead of struct page *.
>  - move functions to the place before relay_mmap_buf.
>  - add comments.
> 
> This is useful for a 64-bit system which has a plenty of memory (tens of
> giga bytes) and a large kernel memory space.
> 
> I tested it on x86-64 and ia64.
> 

Hi,

Looks fine to me.

Reviewed-by: Tom Zanussi <tzanussi@gmail.com>

Re: [PATCH -mm] relayfs: support larger relay buffer

[Pekka Enberg]

On Tue, Apr 15, 2008 at 6:27 PM, Masami Hiramatsu <mhiramat@redhat.com> wrote:
> Use vmalloc() and memset() instead of kcalloc() to allocate a page* array
>  when the array size is bigger than one page. This enables relayfs to support
>  bigger relay buffers than 64MB on 4k-page system, 512MB on 16k-page system.
>
>  Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
>  ---
>  @@ -130,7 +138,10 @@ static void *relay_alloc_buf(struct rcha
>   depopulate:
>         for (j = 0; j < i; j++)
>                 __free_page(buf->page_array[j]);
>  -       kfree(buf->page_array);
>  +       if (pa_size > PAGE_SIZE)

You can use is_vmalloc_addr() here.

>  +               vfree(buf->page_array);
>  +       else
>  +               kfree(buf->page_array);
>         return NULL;
>   }
>

Re: [PATCH -mm] relayfs: support larger relay buffer

[Masami Hiramatsu]

Hi Pekka,

Pekka Enberg wrote:
> On Tue, Apr 15, 2008 at 6:27 PM, Masami Hiramatsu <mhiramat@redhat.com> wrote:
>> Use vmalloc() and memset() instead of kcalloc() to allocate a page* array
>>  when the array size is bigger than one page. This enables relayfs to support
>>  bigger relay buffers than 64MB on 4k-page system, 512MB on 16k-page system.
>>
>>  Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
>>  ---
>>  @@ -130,7 +138,10 @@ static void *relay_alloc_buf(struct rcha
>>   depopulate:
>>         for (j = 0; j < i; j++)
>>                 __free_page(buf->page_array[j]);
>>  -       kfree(buf->page_array);
>>  +       if (pa_size > PAGE_SIZE)
> 
> You can use is_vmalloc_addr() here.

Thank you for your good advice!
I'll use that.

> 
>>  +               vfree(buf->page_array);
>>  +       else
>>  +               kfree(buf->page_array);
>>         return NULL;
>>   }
>>

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com