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SubjectRe: [PATCH 10/19] x86, mpx: Trace the attempts to find bounds tables
On Mon, 18 May 2015, Dave Hansen wrote:
>
> From: Dave Hansen <dave.hansen@linux.intel.com>
>
> There are two different events being traced here. They are
> doing similar things so share a trace "EVENT_CLASS" and are
> presented together.
>
> 1. Trace when MPX is zapping pages "mpx_unmap_zap":
>
> When MPX can not free an entire bounds table, it will
> instead try to zap unused parts of a bounds table to free
> the backing memory. This decreases RSS (resident set
> size) without decreasing the virtual space allocated
> for bounds tables.
>
> 2. Trace attempts to find bounds tables "mpx_unmap_search":
>
> This event traces any time we go looking to unmap a
> bounds table for a given virtual address range. This is
> useful to ensure that the kernel actually "tried" to free
> a bounds table versus times it succeeded in finding one.
>
> It might try and fail if it realized that a table was
> shared with an adjacent VMA which is not being unmapped.
>
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>


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