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Date: Fri, 27 Mar 2015 13:26:17 +0100
From: Borislav Petkov <bp@alien8.de>
To: Dave Hansen <dave@sr71.net>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de,
        dave.hansen@linux.intel.com
Subject: Re: [PATCH 05/17] x86, mpx: trace when MPX is zapping pages
Message-ID: <20150327122617.GD18927@pd.tnic>
References: <20150326183327.64807530@viggo.jf.intel.com>
 <20150326183339.4648B7D9@viggo.jf.intel.com>
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On Thu, Mar 26, 2015 at 11:33:39AM -0700, Dave Hansen wrote:
> 
> From: Dave Hansen <dave.hansen@linux.intel.com>
> 
> 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) without decreasing

			  RSS (Resident Set Size)

> the virtual space allocated for bounds tables.
> 
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
> ---
> 
>  b/arch/x86/include/asm/trace/mpx.h |   22 ++++++++++++++++++++++
>  b/arch/x86/mm/mpx.c                |    1 +
>  2 files changed, 23 insertions(+)
> 
> diff -puN arch/x86/include/asm/trace/mpx.h~mpx-trace_unmap_zap arch/x86/include/asm/trace/mpx.h
> --- a/arch/x86/include/asm/trace/mpx.h~mpx-trace_unmap_zap	2015-03-26 11:27:06.279273832 -0700
> +++ b/arch/x86/include/asm/trace/mpx.h	2015-03-26 11:27:06.283274012 -0700
> @@ -53,6 +53,28 @@ TRACE_EVENT(bounds_exception_mpx,
>  		__entry->bndstatus)
>  );
>  
> +TRACE_EVENT(mpx_unmap_zap,
> +
> +	TP_PROTO(unsigned long start,
> +		 unsigned long end),
> +	TP_ARGS(start, end),
> +
> +	TP_STRUCT__entry(
> +		__field(unsigned long, start)
> +		__field(unsigned long, end)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->start = start;
> +		__entry->end   = end;
> +	),
> +
> +	TP_printk("0x%p -> 0x%p",

Maybe as an interval:

	[0x%p:0x%p]

> +		(void *)__entry->start,
> +		(void *)__entry->end
> +	)
> +);
> +
>  #else

-- 
Regards/Gruss,
    Boris.

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