Re: [PATCH v2 2/2] swiotlb: checking whether swiotlb buffer is full with io_tlb_used

[Konrad Rzeszutek Wilk]

On Mon, Dec 10, 2018 at 08:37:58AM +0800, Dongli Zhang wrote:
> This patch uses io_tlb_used to help check whether swiotlb buffer is full.
> io_tlb_used is no longer used for only debugfs. It is also used to help
> optimize swiotlb_tbl_map_single().

Please split this up.

That is have the 'if (unlikely(nslots > io_tlb_nslabs - io_tlb_used))'
as a seperate patch.

And the #ifdef folding in the previous patch.

Also rebase on top of latest Linus please.

> 
> Suggested-by: Joe Jin 
> Signed-off-by: Dongli Zhang 
> ---
>  kernel/dma/swiotlb.c | 10 --
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 3979c2c..9300341 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -76,12 +76,10 @@ static phys_addr_t io_tlb_start, io_tlb_end;
>   */
>  static unsigned long io_tlb_nslabs;
>  
> -#ifdef CONFIG_DEBUG_FS
>  /*
>   * The number of used IO TLB block
>   */
>  static unsigned long io_tlb_used;
> -#endif
>  
>  /*
>   * This is a free list describing the number of free entries available from
> @@ -489,6 +487,10 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
>* request and allocate a buffer from that IO TLB pool.
>*/
>   spin_lock_irqsave(_tlb_lock, flags);
> +
> + if (unlikely(nslots > io_tlb_nslabs - io_tlb_used))
> + goto not_found;
> +
>   index = ALIGN(io_tlb_index, stride);
>   if (index >= io_tlb_nslabs)
>   index = 0;
> @@ -538,9 +540,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
>   dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes)\n", 
> size);
>   return SWIOTLB_MAP_ERROR;
>  found:
> -#ifdef CONFIG_DEBUG_FS
>   io_tlb_used += nslots;
> -#endif
>   spin_unlock_irqrestore(_tlb_lock, flags);
>  
>   /*
> @@ -602,9 +602,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, 
> phys_addr_t tlb_addr,
>   for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != 
> IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
>   io_tlb_list[i] = ++count;
>  
> -#ifdef CONFIG_DEBUG_FS
>   io_tlb_used -= nslots;
> -#endif
>   }
>   spin_unlock_irqrestore(_tlb_lock, flags);
>  }
> -- 
> 2.7.4
> 
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Re: [PATCH v2 2/2] swiotlb: checking whether swiotlb buffer is full with io_tlb_used

[Joe Jin]

On 12/9/18 4:37 PM, Dongli Zhang wrote:
> This patch uses io_tlb_used to help check whether swiotlb buffer is full.
> io_tlb_used is no longer used for only debugfs. It is also used to help
> optimize swiotlb_tbl_map_single().
> 
> Suggested-by: Joe Jin 
> Signed-off-by: Dongli Zhang 

Reviewed-by: Joe Jin 

> ---
>  kernel/dma/swiotlb.c | 10 --
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 3979c2c..9300341 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -76,12 +76,10 @@ static phys_addr_t io_tlb_start, io_tlb_end;
>   */
>  static unsigned long io_tlb_nslabs;
>  
> -#ifdef CONFIG_DEBUG_FS
>  /*
>   * The number of used IO TLB block
>   */
>  static unsigned long io_tlb_used;
> -#endif
>  
>  /*
>   * This is a free list describing the number of free entries available from
> @@ -489,6 +487,10 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
>* request and allocate a buffer from that IO TLB pool.
>*/
>   spin_lock_irqsave(_tlb_lock, flags);
> +
> + if (unlikely(nslots > io_tlb_nslabs - io_tlb_used))
> + goto not_found;
> +
>   index = ALIGN(io_tlb_index, stride);
>   if (index >= io_tlb_nslabs)
>   index = 0;
> @@ -538,9 +540,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
>   dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes)\n", 
> size);
>   return SWIOTLB_MAP_ERROR;
>  found:
> -#ifdef CONFIG_DEBUG_FS
>   io_tlb_used += nslots;
> -#endif
>   spin_unlock_irqrestore(_tlb_lock, flags);
>  
>   /*
> @@ -602,9 +602,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, 
> phys_addr_t tlb_addr,
>   for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != 
> IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
>   io_tlb_list[i] = ++count;
>  
> -#ifdef CONFIG_DEBUG_FS
>   io_tlb_used -= nslots;
> -#endif
>   }
>   spin_unlock_irqrestore(_tlb_lock, flags);
>  }
> 


-- 
Oracle 
Joe Jin | Software Development Director 
ORACLE | Linux and Virtualization
500 Oracle Parkway Redwood City, CA US 94065
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[PATCH v2 2/2] swiotlb: checking whether swiotlb buffer is full with io_tlb_used

[Dongli Zhang]

This patch uses io_tlb_used to help check whether swiotlb buffer is full.
io_tlb_used is no longer used for only debugfs. It is also used to help
optimize swiotlb_tbl_map_single().

Suggested-by: Joe Jin 
Signed-off-by: Dongli Zhang 
---
 kernel/dma/swiotlb.c | 10 --
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 3979c2c..9300341 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -76,12 +76,10 @@ static phys_addr_t io_tlb_start, io_tlb_end;
  */
 static unsigned long io_tlb_nslabs;
 
-#ifdef CONFIG_DEBUG_FS
 /*
  * The number of used IO TLB block
  */
 static unsigned long io_tlb_used;
-#endif
 
 /*
  * This is a free list describing the number of free entries available from
@@ -489,6 +487,10 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
 * request and allocate a buffer from that IO TLB pool.
 */
spin_lock_irqsave(_tlb_lock, flags);
+
+   if (unlikely(nslots > io_tlb_nslabs - io_tlb_used))
+   goto not_found;
+
index = ALIGN(io_tlb_index, stride);
if (index >= io_tlb_nslabs)
index = 0;
@@ -538,9 +540,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes)\n", 
size);
return SWIOTLB_MAP_ERROR;
 found:
-#ifdef CONFIG_DEBUG_FS
io_tlb_used += nslots;
-#endif
spin_unlock_irqrestore(_tlb_lock, flags);
 
/*
@@ -602,9 +602,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, 
phys_addr_t tlb_addr,
for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != 
IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
io_tlb_list[i] = ++count;
 
-#ifdef CONFIG_DEBUG_FS
io_tlb_used -= nslots;
-#endif
}
spin_unlock_irqrestore(_tlb_lock, flags);
 }
-- 
2.7.4

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