I will build the next RFC version of 64-bit swiotlb on top of this patch (or
next version of this patch), so that it will render a more finalized view of
32-bt/64-bit plus multiple area.
Thank you very much!
Dongli Zhang
On 6/22/22 3:54 AM, Christoph Hellwig wrote:
> Thanks,
>
> this looks pretty good to me. A few comments below:
>
> On Fri, Jun 17, 2022 at 10:47:41AM -0400, Tianyu Lan wrote:
>> +/**
>> + * struct io_tlb_area - IO TLB memory area descriptor
>> + *
>> + * This is a single area with a single lock.
>> + *
>> + * @used: The number of used IO TLB block.
>> + * @index: The slot index to start searching in this area for next round.
>> + * @lock: The lock to protect the above data structures in the map and
>> + * unmap calls.
>> + */
>> +struct io_tlb_area {
>> + unsigned long used;
>> + unsigned int index;
>> + spinlock_t lock;
>> +};
>
> This can go into swiotlb.c.
>
>> +void __init swiotlb_adjust_nareas(unsigned int nareas);
>
> And this should be marked static.
>
>> +#define DEFAULT_NUM_AREAS 1
>
> I'd drop this define, the magic 1 and a > 1 comparism seems to
> convey how it is used much better as the checks aren't about default
> or not, but about larger than one.
>
> I also think that we want some good way to size the default, e.g.
> by number of CPUs or memory size.
>
>> +void __init swiotlb_adjust_nareas(unsigned int nareas)
>> +{
>> + if (!is_power_of_2(nareas)) {
>> + pr_err("swiotlb: Invalid areas parameter %d.\n", nareas);
>> + return;
>> + }
>> +
>> + default_nareas = nareas;
>> +
>> + pr_info("area num %d.\n", nareas);
>> + /* Round up number of slabs to the next power of 2.
>> + * The last area is going be smaller than the rest if
>> + * default_nslabs is not power of two.
>> + */
>
> Please follow the normal kernel comment style with a /* on its own line.
>
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