linux-kernel - Re: [PATCH] iommu/iova: Optimize iova_magazine

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Date:   Thu, 20 Apr 2023 19:52:14 +0800
From:   "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
To:     Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        <iommu@...ts.linux.dev>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iommu/iova: Optimize iova_magazine_alloc()



On 2023/4/20 18:38, Robin Murphy wrote:
> On 2023-04-18 07:25, Zhen Lei wrote:
>> Only the member 'size' needs to be initialized to 0. Clearing the array
>> pfns[], which is about 1 KiB in size, not only wastes time, but also
>> causes cache pollution.
> 
> Makes sense to me.
> 
> Acked-by: Robin Murphy <robin.murphy@....com>
> 
>> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
>> ---
>>   drivers/iommu/iova.c | 8 +++++++-
>>   1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
>> index fe452ce466429a7..c970b9a2819d7bb 100644
>> --- a/drivers/iommu/iova.c
>> +++ b/drivers/iommu/iova.c
>> @@ -647,7 +647,13 @@ struct iova_rcache {
>>     static struct iova_magazine *iova_magazine_alloc(gfp_t flags)
>>   {
>> -    return kzalloc(sizeof(struct iova_magazine), flags);
>> +    struct iova_magazine *mag;
>> +
>> +    mag = kmalloc(sizeof(struct iova_magazine), flags);
> 
> Nit: maybe sizeof(*mag) is preferable?

Yes, sizeof(*mag) is the more recommended usage, I will post v2 tomorrow.

> 
>> +    if (mag)
>> +        mag->size = 0;
>> +
>> +    return mag;
>>   }
>>     static void iova_magazine_free(struct iova_magazine *mag)
> 
> .
> 

-- 
Regards,
  Zhen Lei