linux-kernel - Re: [PATCH V4 4/6] perf/amd/iommu: Introduce get_iommu_bnk_cnt_evt

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Date:	Thu, 18 Feb 2016 12:45:47 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
Cc:	joro@...tes.org, peterz@...radead.org, mingo@...hat.com,
	acme@...nel.org, andihartmann@...enet.de,
	linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org
Subject: Re: [PATCH V4 4/6] perf/amd/iommu: Introduce
 get_iommu_bnk_cnt_evt_idx

On Thu, Feb 11, 2016 at 04:15:25PM +0700, Suravee Suthikulpanit wrote:
> Introduce a helper function to calculate bit-index for assigning
> performance counter assignment.
> 
> Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
> ---
>  arch/x86/events/amd/iommu.c | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/events/amd/iommu.c b/arch/x86/events/amd/iommu.c
> index debf22d..812eff2 100644
> --- a/arch/x86/events/amd/iommu.c
> +++ b/arch/x86/events/amd/iommu.c
> @@ -145,18 +145,27 @@ static struct attribute_group amd_iommu_cpumask_group = {
>  
>  /*---------------------------------------------*/
>  
> +static inline
> +int get_iommu_bnk_cnt_evt_idx(struct perf_amd_iommu *perf_iommu,
> +				  int iommu_index, int bank_index,
> +				  int cntr_index)

Align args at the opening brace.

> +{
> +	int cntrs_per_iommu = perf_iommu->max_banks * perf_iommu->max_counters;
> +	int index = (perf_iommu->max_counters * bank_index) + cntr_index;
> +
> +	return (cntrs_per_iommu * iommu_index) + index;
> +}
> +
>  static int get_next_avail_iommu_bnk_cntr(struct perf_amd_iommu *perf_iommu)
>  {
>  	unsigned long flags;
>  	int shift, bank, cntr, retval;
> -	int max_banks = perf_iommu->max_banks;
> -	int max_cntrs = perf_iommu->max_counters;
>  
>  	raw_spin_lock_irqsave(&perf_iommu->lock, flags);
>  
> -	for (bank = 0, shift = 0; bank < max_banks; bank++) {
> -		for (cntr = 0; cntr < max_cntrs; cntr++) {
> -			shift = bank + (bank*3) + cntr;
> +	for (bank = 0, shift = 0; bank < perf_iommu->max_banks; bank++) {

Please init that shift variable above in the function entry - it
confuses unnecessarily here as if it had anything to do with the loop
stride.

> +		for (cntr = 0; cntr < perf_iommu->max_counters; cntr++) {
> +			shift = get_iommu_bnk_cnt_evt_idx(perf_iommu, 0, bank, cntr);

\n here

>  			if (perf_iommu->cntr_assign_mask & (1ULL<<shift)) {
>  				continue;
>  			} else {
> -- 
> 2.5.0
> 
> 

-- 
Regards/Gruss,
    Boris.

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