netdev - Re: [PATCH V3 13/13] HV/Storvsc: Add Isolation VM support for storvsc driver

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Date:   Tue, 24 Aug 2021 10:46:46 +0200
From:   "hch@....de" <hch@....de>
To:     Tianyu Lan <ltykernel@...il.com>
Cc:     Michael Kelley <mikelley@...rosoft.com>,
        KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
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Subject: Re: [PATCH V3 13/13] HV/Storvsc: Add Isolation VM support for
 storvsc driver

On Sat, Aug 21, 2021 at 02:04:11AM +0800, Tianyu Lan wrote:
> After dma_map_sg(), we still need to go through scatter list again to 
> populate payload->rrange.pfn_array. We may just go through the scatter list 
> just once if dma_map_sg() accepts a callback and run it during go
> through scatter list.

Iterating a cache hot array is way faster than doing lots of indirect
calls.