> [   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)


> --- 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?
No need here.

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

Is the (unsigned long) cast needed?
No need here.



发件人: Andrew Morton <akpm@linux-foundation.org>
发送时间: 2024年9月25日 8:27:19
收件人: Xiang Gao
抄送: linux-mm@kvack.org; linux-kernel@vger.kernel.org; 高翔
主题: [External Mail]Re: [PATCH] mm/cma.c: To better understand cma area during debugging, add total and used count logs to in cma_alloc
 
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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
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