linux-kernel - Re: [PATCH v2 1/2] iommu/vt-d: Ratelimit fault handler

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Message-ID: <1458246810.9556.22.camel@perches.com>
Date:	Thu, 17 Mar 2016 13:33:30 -0700
From:	Joe Perches <joe@...ches.com>
To:	Alex Williamson <alex.williamson@...hat.com>,
	iommu@...ts.linux-foundation.org, dwmw2@...radead.org
Cc:	joro@...tes.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] iommu/vt-d: Ratelimit fault handler

On Thu, 2016-03-17 at 14:12 -0600, Alex Williamson wrote:
> Fault rates can easily overwhelm the console and make the system
> unresponsive.  Ratelimit to allow an opportunity for maintenance.
[]
> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
[]
> @@ -1602,10 +1602,17 @@ irqreturn_t dmar_fault(int irq, void *dev_id)
>  	int reg, fault_index;
>  	u32 fault_status;
>  	unsigned long flag;
> +	bool ratelimited;
> +	static DEFINE_RATELIMIT_STATE(rs,
> +				      DEFAULT_RATELIMIT_INTERVAL,
> +				      DEFAULT_RATELIMIT_BURST);

Are these the appropriate limits for dmar?

include/linux/ratelimit.h:#define DEFAULT_RATELIMIT_INTERVAL    (5 * HZ)
include/linux/ratelimit.h:#define DEFAULT_RATELIMIT_BURST       10