linux-kernel - Re: [PATCH 2/2] ntb: make DMA_OUT_RESOURCE

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Date:   Mon, 22 Aug 2016 16:58:27 +0000
From:   "Jiang, Dave" <dave.jiang@...el.com>
To:     "hofrat@...dl.org" <hofrat@...dl.org>,
        "jdmason@...zu.us" <jdmason@...zu.us>
CC:     "Allen.Hubbe@....com" <Allen.Hubbe@....com>,
        "logang@...tatee.com" <logang@...tatee.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "sudipm.mukherjee@...il.com" <sudipm.mukherjee@...il.com>,
        "arnd@...db.de" <arnd@...db.de>,
        "linux-ntb@...glegroups.com" <linux-ntb@...glegroups.com>
Subject: Re: [PATCH 2/2] ntb: make DMA_OUT_RESOURCE_TO HZ independent


On Mon, 2016-08-22 at 18:51 +0200, Nicholas Mc Guire wrote:
> schedule_timeout_* takes a timeout in jiffies but the code currently
> is
> passing in a constant which makes this timeout HZ dependent, so pass
> it
> through msecs_to_jiffies() to fix this up.
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>

Acked-by: Dave Jiang <dave.jiang@...el.com>


> ---
> 
> Problem found by coccinelle script
> 
> The below patch sets the timeout to 50ms - not clear what HZ setting
> was
> assumed during design/testing, so this needs an ack by someone who
> knows
> the driver and can confirm that 50ms is reasonable to wait on DMA
> retries.
> 
> Patch was compile tested with: x86_64_defconfig + CONFIG_NTB=m,
> CONFIG_NTB_PERF=m
> 
> Patch is against 4.8.0-rc2 (localversion-next is -next-20160822)
> 
>  drivers/ntb/test/ntb_perf.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/ntb/test/ntb_perf.c
> b/drivers/ntb/test/ntb_perf.c
> index 6a50f20..e065b69 100644
> --- a/drivers/ntb/test/ntb_perf.c
> +++ b/drivers/ntb/test/ntb_perf.c
> @@ -72,7 +72,7 @@
>  #define MAX_THREADS		32
>  #define MAX_TEST_SIZE		SZ_1M
>  #define MAX_SRCS		32
> -#define DMA_OUT_RESOURCE_TO	50
> +#define DMA_OUT_RESOURCE_TO	msecs_to_jiffies(50)
>  #define DMA_RETRIES		20
>  #define SZ_4G			(1ULL << 32)
>  #define MAX_SEG_ORDER		20 /* no larger than 1M for
> kmalloc buffer */
> -- 
> 2.1.4
>