linux-kernel - Re: [PATCH V2 5/5] perf/x86: Add Intel Nehalem-EX uncore support

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Message-ID: <20120705145124.GS11413@one.firstfloor.org>
Date:	Thu, 5 Jul 2012 16:51:24 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	"Yan, Zheng" <zheng.z.yan@...el.com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>, eranian@...gle.com,
	mingo@...e.hu, andi@...stfloor.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 5/5] perf/x86: Add Intel Nehalem-EX uncore support

On Thu, Jul 05, 2012 at 02:32:17PM +0800, Yan, Zheng wrote:
> The uncore subsystem in Nehalem-EX consists of 7 components
> (U-Box, C-Box, B-Box, S-Box, R-Box, M-Box and W-Box). This
> patch is large because the way to program these boxes is
> diverse.

Thanks for doing the driver. Lots of work.

May be worth adding a CONFIG for the uncore code now?
Maybe even a module, so that not every distro kernel has it always
in memory. I don't think perf has support for tracking
module counts, but I guess it would be ok to have the module be not
unloadable once loaded by setting the count to -1.

Also did you do some random testing by putting randomized values into
all the exported registers and see if anything is crashable for 
unpriv. userspace?

> +		 * events are functional identical, but use different
> +		 * extra registers. If we failed to take an extra
> +		 * register, try the alternative.
> +		 */
> +		if (idx % 2)
> +			idx--;
> +		else
> +			idx++;
> +		if (idx != reg1->idx % 6) {
> +			if (idx == 2)
> +				config1 >>= 8;
> +			else if (idx == 3)
> +				config1 <<= 8;
> +			goto again;

Does this limit the retries?

> @@ -1767,6 +2821,9 @@ static int __init uncore_cpu_init(void)
>  			snbep_uncore_cbox.num_boxes = max_cores;
>  		msr_uncores = snbep_msr_uncores;
>  		break;
> +	case 46:
> +		msr_uncores = nhmex_msr_uncores;
> +		break;

Ok need Westmere-EX too. I think that is quite similar.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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