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Subject: Re: [PATCH 2/2] dmaengine: ioat: Decreasing allocation chunk size 2M
 -> 512K
To:     leonid.ravich@dell.com, dmaengine@vger.kernel.org
Cc:     lravich@gmail.com, Vinod Koul <vkoul@kernel.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Alexios Zavras <alexios.zavras@intel.com>,
        "Alexander.Barabash@dell.com" <Alexander.Barabash@dell.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Kate Stewart <kstewart@linuxfoundation.org>,
        Jilayne Lovejoy <opensource@jilayne.com>,
        Logan Gunthorpe <logang@deltatee.com>,
        linux-kernel@vger.kernel.org
References: <20200402092725.15121-1-leonid.ravich@dell.com>
 <20200402092725.15121-2-leonid.ravich@dell.com>
From:   Dave Jiang <dave.jiang@intel.com>
Message-ID: <793bc07b-fec9-27ee-7eff-203326e3608a@intel.com>
Date:   Thu, 2 Apr 2020 08:06:19 -0700
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On 4/2/2020 2:27 AM, leonid.ravich@dell.com wrote:
> From: Leonid Ravich <Leonid.Ravich@emc.com>
> 
> current IOAT driver using big (2MB) allocations chunk for its descriptors
> therefore each ioat dma engine need 2 such chunks
> (64k entres in ring  each entry 64B = 4MB)
> requiring 2 * 2M * dmaengine contiguies memory chunk
> might fail due to memory fragmention.
> 
> so we decresging chunk size and using more chunks.

decreasing

> 
> Signed-off-by: Leonid Ravich <Leonid.Ravich@emc.com>

Acked-by: Dave Jiang <dave.jiang@intel.com> if the two patches have been 
tested on hw.

> ---
>   drivers/dma/ioat/dma.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/dma/ioat/dma.h b/drivers/dma/ioat/dma.h
> index 535aba9..e9757bc 100644
> --- a/drivers/dma/ioat/dma.h
> +++ b/drivers/dma/ioat/dma.h
> @@ -83,7 +83,7 @@ struct ioatdma_device {
>   
>   #define IOAT_MAX_ORDER 16
>   #define IOAT_MAX_DESCS (1 << IOAT_MAX_ORDER)
> -#define IOAT_CHUNK_SIZE (SZ_2M)
> +#define IOAT_CHUNK_SIZE (SZ_512K)
>   #define IOAT_DESCS_PER_CHUNK (IOAT_CHUNK_SIZE/IOAT_DESC_SZ)
>   
>   struct ioat_descs {
>