From: Qian Cai
> Sent: 30 November 2018 21:48
> To: h...@lst.de; m.szyprow...@samsung.com; robin.mur...@arm.com
> Cc: yisen.zhu...@huawei.com; salil.me...@huawei.com; john.ga...@huawei.com;
> linux...@huawei.com;
> io...@lists.linux-foundation.org; netdev@vger.kernel.org;
> linux-ker...@vger.kernel.org; Qian Cai
> Subject: [PATCH v2] dma-debug: Kconfig for PREALLOC_DMA_DEBUG_ENTRIES
>
> The amount of DMA mappings from Hisilicon HNS ethernet devices is huge,
> so it could trigger "DMA-API: debugging out of memory - disabling".
>
> hnae_get_handle [1]
> hnae_init_queue
> hnae_init_ring
> hnae_alloc_buffers [2]
> debug_dma_map_page
> dma_entry_alloc
>
> [1] for (i = 0; i < handle->q_num; i++)
> [2] for (i = 0; i < ring->desc_num; i++)
>
> Also, "#define HNS_DSAF_MAX_DESC_CNT 1024"
>
> On this Huawei TaiShan 2280 aarch64 server, it has reached the limit
> already,
>
> 4 (NICs) x 16 (queues) x 1024 (port descption numbers) = 65536
>
> Added a Kconfig entry for PREALLOC_DMA_DEBUG_ENTRIES, so make it easier
> for users to deal with special cases like this.
Ugg. That is worse than a module parameter.
The driver needs to automatically reduce the number of mapping requests.
David
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