On 12/9/20 10:59 AM, Joao Martins wrote:
> On 12/8/20 7:29 PM, Jason Gunthorpe wrote:
>> On Tue, Dec 08, 2020 at 05:29:00PM +0000, Joao Martins wrote:
>>
>>> static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem,
>>> int dirty)
>>> {
>>> + bool make_dirty = umem->writable && dirty;
>>> + struct page **page_list = NULL;
>>> struct sg_page_iter sg_iter;
>>> + unsigned long nr = 0;
>>> struct page *page;
>>>
>>> + page_list = (struct page **) __get_free_page(GFP_KERNEL);
>>
>> Gah, no, don't do it like this!
>>
>> Instead something like:
>>
>> for_each_sg(umem->sg_head.sgl, sg, umem->nmap, i)
>> unpin_use_pages_range_dirty_lock(sg_page(sg),
>> sg->length/PAGE_SIZE,
>> umem->writable && dirty);
>>
>> And have the mm implementation split the contiguous range of pages into
>> pairs of (compound head, ntails) with a bit of maths.
>>
> Got it :)
>
> I was trying to avoid another exported symbol.
>
> Albeit upon your suggestion below, it doesn't justify the
> efficiency/clearness lost.
>
This more efficient suggestion of yours leads to a further speed up from:
1073 rounds in 5.004 sec: 4663.622 usec / round (hugetlbfs)
to
1370 rounds in 5.003 sec: 3651.562 usec / round (hugetlbfs)
Right after I come back from holidays I will follow up with this series in
separate.
Joao
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