[PATCH] mm/cma.c: To better understand cma area during debugging, add total and used count logs to in cma_alloc

[PATCH] mm/cma.c: To better understand cma area during debugging, add total and used count logs to in cma_alloc

[Xiang Gao]

From: gaoxiang17 <gaoxiang17@xiaomi.com>

[   24.225125] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 64, request count 1, align 0)
[   24.231963] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 65, request count 1, align 0)
[   24.235712] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 66, request count 1, align 0)

Signed-off-by: gaoxiang17 <gaoxiang17@xiaomi.com>
---
 mm/cma.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/mm/cma.c b/mm/cma.c
index 3e9724716bad..cceff3b6a79e 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -403,6 +403,17 @@ static void cma_debug_show_areas(struct cma *cma)
 	spin_unlock_irq(&cma->lock);
 }
 
+static unsigned long cma_get_used(struct cma *cma)
+{
+	unsigned long used;
+
+	spin_lock_irq(&cma->lock);
+	used = bitmap_weight(cma->bitmap, (int)cma_bitmap_maxno(cma));
+	spin_unlock_irq(&cma->lock);
+
+	return (unsigned long)used << cma->order_per_bit;
+}
+
 /**
  * cma_alloc() - allocate pages from contiguous area
  * @cma:   Contiguous memory region for which the allocation is performed.
@@ -430,8 +441,8 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
 	if (!cma || !cma->count || !cma->bitmap)
 		return page;
 
-	pr_debug("%s(cma %p, name: %s, count %lu, align %d)\n", __func__,
-		(void *)cma, cma->name, count, align);
+	pr_debug("%s(cma %p, name: %s, total count %lu, used count: %lu, request count %lu, align %d)\n", __func__,
+		(void *)cma, cma->name, cma->count, cma_get_used(cma), count, align);
 
 	if (!count)
 		return page;
-- 
2.34.1

Re: [PATCH] mm/cma.c: To better understand cma area during debugging, add total and used count logs to in cma_alloc

[Andrew Morton]

On Wed, 18 Sep 2024 20:43:25 +0800 Xiang Gao <gxxa03070307@gmail.com> wrote:

> From: gaoxiang17 <gaoxiang17@xiaomi.com>
> 
> [   24.225125] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 64, request count 1, align 0)
> [   24.231963] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 65, request count 1, align 0)
> [   24.235712] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 66, request count 1, align 0)
> 

Providing before-and-after output would make the proposal more easily
understood.

> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -403,6 +403,17 @@ static void cma_debug_show_areas(struct cma *cma)
>  	spin_unlock_irq(&cma->lock);
>  }
>  
> +static unsigned long cma_get_used(struct cma *cma)
> +{
> +	unsigned long used;
> +
> +	spin_lock_irq(&cma->lock);
> +	used = bitmap_weight(cma->bitmap, (int)cma_bitmap_maxno(cma));

Is the (int) cast needed?

> +	spin_unlock_irq(&cma->lock);
> +
> +	return (unsigned long)used << cma->order_per_bit;

Is the (unsigned long) bast needed?

> +}
> +
>  /**
>   * cma_alloc() - allocate pages from contiguous area
>   * @cma:   Contiguous memory region for which the allocation is performed.
> @@ -430,8 +441,8 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
>  	if (!cma || !cma->count || !cma->bitmap)
>  		return page;
>  
> -	pr_debug("%s(cma %p, name: %s, count %lu, align %d)\n", __func__,
> -		(void *)cma, cma->name, count, align);
> +	pr_debug("%s(cma %p, name: %s, total count %lu, used count: %lu, request count %lu, align %d)\n", __func__,
> +		(void *)cma, cma->name, cma->count, cma_get_used(cma), count, align);
>  
>  	if (!count)
>  		return page;
> -- 
> 2.34.1

Re: 答复: [External Mail]Re: [PATCH] mm/cma.c: To better understand cma area during debugging, add total and used count logs to in cma_alloc

[Andrew Morton]

On Wed, 25 Sep 2024 12:00:56 +0000 高翔 <gaoxiang17@xiaomi.com> wrote:

> > [   24.225125] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 64, request count 1, align 0)
> > [   24.231963] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 65, request count 1, align 0)
> > [   24.235712] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 66, request count 1, align 0)
> >
> 
> 
> Above is the cma alloc during boot. The before-and-after context has nothing to do with cma alloc. Below is the log with before-and-after context added.
> 
> 
> [   24.006605] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
> [   24.071644] Serial: AMBA driver
> [   24.096063] arm-smmu-v3 9050000.smmuv3: ias 44-bit, oas 44-bit (features 0x00000305)
> [   24.097989] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 64, request count 1, align 0)
> [   24.104260] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 65, request count 1, align 0)
> [   24.107504] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 66, request count 1, align 0)
> [   24.140495] cacheinfo: Unable to detect cache hierarchy for CPU 0
> [   24.484998] loop: module loaded
> [   24.536152] virtio_blk virtio0: [vda] 4194304 512-byte logical blocks (2.15 GB/2.00 GiB)

What I mean is to paste the messages before the patch and to paste the
messages after the patch.  So readers can easily see what changed.

Re: [PATCH] mm/cma.c: To better understand cma area during debugging, add total and used count logs to in cma_alloc

[David Hildenbrand]

On 18.09.24 14:43, Xiang Gao wrote:
> From: gaoxiang17 <gaoxiang17@xiaomi.com>
> 

Please move some of $subject into $description, to make it shorter.

Maybe use the subject:

"mm/cma: print total and used count in cma_alloc()"


-- 
Cheers,

David / dhildenb