linux-kernel - Re: [PATCH] dmaengine: ioat setting ioat timeout as module parameter

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Date:   Wed, 1 Jul 2020 07:25:33 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     leonid.ravich@...l.com, dmaengine@...r.kernel.org
Cc:     lravich@...il.com, Dan Williams <dan.j.williams@...el.com>,
        Vinod Koul <vkoul@...nel.org>,
        "Alexander.Barabash@...l.com" <Alexander.Barabash@...l.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dmaengine: ioat setting ioat timeout as module parameter



On 7/1/2020 7:08 AM, leonid.ravich@...l.com wrote:
> From: Leonid Ravich <Leonid.Ravich@....com>
> 
> DMA transaction time to complition  is a function of
completion

> PCI bandwidth,transaction size and a queue depth.
                 ^ space                channel depth. ioat doesn't have queues.
> So hard coded value for timeouts might be wrong
> for some scenarios.
> 
> Signed-off-by: Leonid Ravich <Leonid.Ravich@....com>
> ---
>   drivers/dma/ioat/dma.c | 12 ++++++++++++
>   drivers/dma/ioat/dma.h |  2 --
>   2 files changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/ioat/dma.c b/drivers/dma/ioat/dma.c
> index 8ad0ad861c86..7621b5be5cf4 100644
> --- a/drivers/dma/ioat/dma.c
> +++ b/drivers/dma/ioat/dma.c
> @@ -26,6 +26,18 @@
>   
>   #include "../dmaengine.h"
>   
> +int complition_timeout = 200;
> +module_param(complition_timeout, int, 0644);
> +MODULE_PARM_DESC(complition_timeout,
> +		"set ioat complition timeout [msec] (default 200 [msec])");

completion_timeout


> +int idle_timeout = 2000;
> +module_param(idle_timeout, int, 0644);
> +MODULE_PARM_DESC(idle_timeout,
> +		"set ioat idel timeout [msec] (default 2000 [msec])");
> +
> +#define IDLE_TIMEOUT msecs_to_jiffies(idle_timeout)
> +#define COMPLETION_TIMEOUT msecs_to_jiffies(complition_timeout)
> +
>   static char *chanerr_str[] = {
>   	"DMA Transfer Source Address Error",
>   	"DMA Transfer Destination Address Error",
> diff --git a/drivers/dma/ioat/dma.h b/drivers/dma/ioat/dma.h
> index e6b622e1ba92..f7f31fdf14cf 100644
> --- a/drivers/dma/ioat/dma.h
> +++ b/drivers/dma/ioat/dma.h
> @@ -104,8 +104,6 @@ struct ioatdma_chan {
>   	#define IOAT_RUN 5
>   	#define IOAT_CHAN_ACTIVE 6
>   	struct timer_list timer;
> -	#define COMPLETION_TIMEOUT msecs_to_jiffies(100)
> -	#define IDLE_TIMEOUT msecs_to_jiffies(2000)
>   	#define RESET_DELAY msecs_to_jiffies(100)
>   	struct ioatdma_device *ioat_dma;
>   	dma_addr_t completion_dma;
>