diff mbox series

[v6,7/7] udmabuf: reuse folio array when pin folios

Message ID 20240909091851.1165742-8-link@vivo.com (mailing list archive)
State New, archived
Headers show
Series udmabuf bug fix and some improvements | expand

Commit Message

Huan Yang Sept. 9, 2024, 9:18 a.m. UTC 
When invoke memfd_pin_folios, we need offer an array to save each folio
which we pinned.

The currently way is dynamic alloc an array, get folios, save into
udmabuf and then free.

If the size is tiny(alloc from slab) is ok due to slab can cache it.
Or, just PCP order can cover, also ok.

But if size is huge, need fallback into vmalloc, then, not well, due to
each page need alloc, and map into vmalloc area. Too heavy.

Now that we need to iter each udmabuf item, then pin it's range folios,
we can reuse the maximum size range's folios array.

Signed-off-by: Huan Yang <link@vivo.com>
Acked-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
---
 drivers/dma-buf/udmabuf.c | 36 +++++++++++++++++++++---------------
 1 file changed, 21 insertions(+), 15 deletions(-)

Comments

Kasireddy, Vivek Sept. 12, 2024, 11:09 p.m. UTC | #1 
Hi Huan,

> Subject: [PATCH v6 7/7] udmabuf: reuse folio array when pin folios
> 
> When invoke memfd_pin_folios, we need offer an array to save each folio
> which we pinned.
> 
> The currently way is dynamic alloc an array, get folios, save into
*current

> udmabuf and then free.
> 
> If the size is tiny(alloc from slab) is ok due to slab can cache it.
> Or, just PCP order can cover, also ok.
A casual reader may not know what is PCP. Please mention what it
stands for and how it is relevant here.

> 
> But if size is huge, need fallback into vmalloc, then, not well, due to
> each page need alloc, and map into vmalloc area. Too heavy.
I think it would be better if the above two lines are rewritten to more clearly
describe why or how fallback to vmalloc adversely affects performance.

Thanks,
Vivek

> 
> Now that we need to iter each udmabuf item, then pin it's range folios,
> we can reuse the maximum size range's folios array.
> 
> Signed-off-by: Huan Yang <link@vivo.com>
> Acked-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
> ---
>  drivers/dma-buf/udmabuf.c | 36 +++++++++++++++++++++---------------
>  1 file changed, 21 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
> index 0e405a589ca2..9fc5d22d54ae 100644
> --- a/drivers/dma-buf/udmabuf.c
> +++ b/drivers/dma-buf/udmabuf.c
> @@ -341,28 +341,20 @@ static int export_udmabuf(struct udmabuf *ubuf,
>  }
> 
>  static long udmabuf_pin_folios(struct udmabuf *ubuf, struct file *memfd,
> -			       loff_t start, loff_t size)
> +			       loff_t start, loff_t size, struct folio **folios)
>  {
>  	pgoff_t nr_pinned = ubuf->nr_pinned;
>  	pgoff_t upgcnt = ubuf->pagecount;
> -	struct folio **folios = NULL;
>  	u32 cur_folio, cur_pgcnt;
>  	pgoff_t pgoff, pgcnt;
>  	long nr_folios;
> -	long ret = 0;
>  	loff_t end;
> 
>  	pgcnt = size >> PAGE_SHIFT;
> -	folios = kvmalloc_array(pgcnt, sizeof(*folios), GFP_KERNEL);
> -	if (!folios)
> -		return -ENOMEM;
> -
>  	end = start + (pgcnt << PAGE_SHIFT) - 1;
>  	nr_folios = memfd_pin_folios(memfd, start, end, folios, pgcnt,
> &pgoff);
> -	if (nr_folios <= 0) {
> -		ret = nr_folios ? nr_folios : -EINVAL;
> -		goto end;
> -	}
> +	if (nr_folios <= 0)
> +		return nr_folios ? nr_folios : -EINVAL;
> 
>  	cur_pgcnt = 0;
>  	for (cur_folio = 0; cur_folio < nr_folios; ++cur_folio) {
> @@ -391,14 +383,15 @@ static long udmabuf_pin_folios(struct udmabuf
> *ubuf, struct file *memfd,
>  end:
>  	ubuf->pagecount = upgcnt;
>  	ubuf->nr_pinned = nr_pinned;
> -	kvfree(folios);
> -	return ret;
> +	return 0;
>  }
> 
>  static long udmabuf_create(struct miscdevice *device,
>  			   struct udmabuf_create_list *head,
>  			   struct udmabuf_create_item *list)
>  {
> +	unsigned long max_nr_folios = 0;
> +	struct folio **folios = NULL;
>  	pgoff_t pgcnt = 0, pglimit;
>  	struct udmabuf *ubuf;
>  	long ret = -EINVAL;
> @@ -410,14 +403,19 @@ static long udmabuf_create(struct miscdevice
> *device,
> 
>  	pglimit = (size_limit_mb * 1024 * 1024) >> PAGE_SHIFT;
>  	for (i = 0; i < head->count; i++) {
> +		pgoff_t subpgcnt;
> +
>  		if (!PAGE_ALIGNED(list[i].offset))
>  			goto err_noinit;
>  		if (!PAGE_ALIGNED(list[i].size))
>  			goto err_noinit;
> 
> -		pgcnt += list[i].size >> PAGE_SHIFT;
> +		subpgcnt = list[i].size >> PAGE_SHIFT;
> +		pgcnt += subpgcnt;
>  		if (pgcnt > pglimit)
>  			goto err_noinit;
> +
> +		max_nr_folios = max_t(unsigned long, subpgcnt,
> max_nr_folios);
>  	}
> 
>  	if (!pgcnt)
> @@ -427,6 +425,12 @@ static long udmabuf_create(struct miscdevice
> *device,
>  	if (ret)
>  		goto err;
> 
> +	folios = kvmalloc_array(max_nr_folios, sizeof(*folios), GFP_KERNEL);
> +	if (!folios) {
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
>  	for (i = 0; i < head->count; i++) {
>  		struct file *memfd = fget(list[i].memfd);
> 
> @@ -442,7 +446,7 @@ static long udmabuf_create(struct miscdevice
> *device,
>  		}
> 
>  		ret = udmabuf_pin_folios(ubuf, memfd, list[i].offset,
> -					 list[i].size);
> +					 list[i].size, folios);
>  		fput(memfd);
>  		if (ret)
>  			goto err;
> @@ -453,12 +457,14 @@ static long udmabuf_create(struct miscdevice
> *device,
>  	if (ret < 0)
>  		goto err;
> 
> +	kvfree(folios);
>  	return ret;
> 
>  err:
>  	deinit_udmabuf(ubuf);
>  err_noinit:
>  	kfree(ubuf);
> +	kvfree(folios);
>  	return ret;
>  }
> 
> --
> 2.45.2
diff mbox series

Patch

diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index 0e405a589ca2..9fc5d22d54ae 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -341,28 +341,20 @@  static int export_udmabuf(struct udmabuf *ubuf,
 }
 
 static long udmabuf_pin_folios(struct udmabuf *ubuf, struct file *memfd,
-			       loff_t start, loff_t size)
+			       loff_t start, loff_t size, struct folio **folios)
 {
 	pgoff_t nr_pinned = ubuf->nr_pinned;
 	pgoff_t upgcnt = ubuf->pagecount;
-	struct folio **folios = NULL;
 	u32 cur_folio, cur_pgcnt;
 	pgoff_t pgoff, pgcnt;
 	long nr_folios;
-	long ret = 0;
 	loff_t end;
 
 	pgcnt = size >> PAGE_SHIFT;
-	folios = kvmalloc_array(pgcnt, sizeof(*folios), GFP_KERNEL);
-	if (!folios)
-		return -ENOMEM;
-
 	end = start + (pgcnt << PAGE_SHIFT) - 1;
 	nr_folios = memfd_pin_folios(memfd, start, end, folios, pgcnt, &pgoff);
-	if (nr_folios <= 0) {
-		ret = nr_folios ? nr_folios : -EINVAL;
-		goto end;
-	}
+	if (nr_folios <= 0)
+		return nr_folios ? nr_folios : -EINVAL;
 
 	cur_pgcnt = 0;
 	for (cur_folio = 0; cur_folio < nr_folios; ++cur_folio) {
@@ -391,14 +383,15 @@  static long udmabuf_pin_folios(struct udmabuf *ubuf, struct file *memfd,
 end:
 	ubuf->pagecount = upgcnt;
 	ubuf->nr_pinned = nr_pinned;
-	kvfree(folios);
-	return ret;
+	return 0;
 }
 
 static long udmabuf_create(struct miscdevice *device,
 			   struct udmabuf_create_list *head,
 			   struct udmabuf_create_item *list)
 {
+	unsigned long max_nr_folios = 0;
+	struct folio **folios = NULL;
 	pgoff_t pgcnt = 0, pglimit;
 	struct udmabuf *ubuf;
 	long ret = -EINVAL;
@@ -410,14 +403,19 @@  static long udmabuf_create(struct miscdevice *device,
 
 	pglimit = (size_limit_mb * 1024 * 1024) >> PAGE_SHIFT;
 	for (i = 0; i < head->count; i++) {
+		pgoff_t subpgcnt;
+
 		if (!PAGE_ALIGNED(list[i].offset))
 			goto err_noinit;
 		if (!PAGE_ALIGNED(list[i].size))
 			goto err_noinit;
 
-		pgcnt += list[i].size >> PAGE_SHIFT;
+		subpgcnt = list[i].size >> PAGE_SHIFT;
+		pgcnt += subpgcnt;
 		if (pgcnt > pglimit)
 			goto err_noinit;
+
+		max_nr_folios = max_t(unsigned long, subpgcnt, max_nr_folios);
 	}
 
 	if (!pgcnt)
@@ -427,6 +425,12 @@  static long udmabuf_create(struct miscdevice *device,
 	if (ret)
 		goto err;
 
+	folios = kvmalloc_array(max_nr_folios, sizeof(*folios), GFP_KERNEL);
+	if (!folios) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
 	for (i = 0; i < head->count; i++) {
 		struct file *memfd = fget(list[i].memfd);
 
@@ -442,7 +446,7 @@  static long udmabuf_create(struct miscdevice *device,
 		}
 
 		ret = udmabuf_pin_folios(ubuf, memfd, list[i].offset,
-					 list[i].size);
+					 list[i].size, folios);
 		fput(memfd);
 		if (ret)
 			goto err;
@@ -453,12 +457,14 @@  static long udmabuf_create(struct miscdevice *device,
 	if (ret < 0)
 		goto err;
 
+	kvfree(folios);
 	return ret;
 
 err:
 	deinit_udmabuf(ubuf);
 err_noinit:
 	kfree(ubuf);
+	kvfree(folios);
 	return ret;
 }