[Intel-gfx] [PATCH 03/13] scatterlist: Add sg_set_folio()
Zhu Yanjun
yanjun.zhu at linux.dev
Fri Aug 18 07:05:14 UTC 2023
在 2023/7/31 5:42, Matthew Wilcox 写道:
> On Sun, Jul 30, 2023 at 09:57:06PM +0800, Zhu Yanjun wrote:
>> 在 2023/7/30 19:18, Matthew Wilcox 写道:
>>> On Sun, Jul 30, 2023 at 07:01:26PM +0800, Zhu Yanjun wrote:
>>>> Does the following function have folio version?
>>>>
>>>> "
>>>> int sg_alloc_append_table_from_pages(struct sg_append_table *sgt_append,
>>>> struct page **pages, unsigned int n_pages, unsigned int offset,
>>>> unsigned long size, unsigned int max_segment,
>>>> unsigned int left_pages, gfp_t gfp_mask)
>>>> "
>>> No -- I haven't needed to convert anything that uses
>>> sg_alloc_append_table_from_pages() yet. It doesn't look like it should
>>> be _too_ hard to add a folio version.
>> In many places, this function is used. So this function needs the folio
>> version.
> It's not used in very many places. But the first one that I see it used
> (drivers/infiniband/core/umem.c), you can't do a straightforward folio
> conversion:
>
> pinned = pin_user_pages_fast(cur_base,
> min_t(unsigned long, npages,
> PAGE_SIZE /
> sizeof(struct page *)),
> gup_flags, page_list);
> ...
> ret = sg_alloc_append_table_from_pages(
> &umem->sgt_append, page_list, pinned, 0,
> pinned << PAGE_SHIFT, ib_dma_max_seg_size(device),
> npages, GFP_KERNEL);
>
> That can't be converted to folios. The GUP might start in the middle of
> the folio, and we have no way to communicate that.
>
> This particular usage really needs the phyr work that Jason is doing so
> we can efficiently communicate physically contiguous ranges from GUP
> to sg.
Hi, Matthew
Thanks. To the following function, it seems that no folio function
replace vmalloc_to_page.
vmalloc_to_page calls virt_to_page to get page. Finally the followings
will be called.
"
(mem_map + ((pfn) - ARCH_PFN_OFFSET))
"
And I do not find the related folio functions with vmalloc_to_page.
And no folio function replaces dma_map_page.
dma_map_page will call dma_map_page_attrs.
Or these 2 function should not be replaced with folio functions?
int irdma_map_vm_page_list(struct irdma_hw *hw, void *va, dma_addr_t
*pg_dma,
u32 pg_cnt)
{
struct page *vm_page;
int i;
u8 *addr;
addr = (u8 *)(uintptr_t)va;
for (i = 0; i < pg_cnt; i++) {
vm_page = vmalloc_to_page(addr);
if (!vm_page)
goto err;
pg_dma[i] = dma_map_page(hw->device, vm_page, 0, PAGE_SIZE,
DMA_BIDIRECTIONAL);
if (dma_mapping_error(hw->device, pg_dma[i]))
goto err;
addr += PAGE_SIZE;
}
return 0;
err:
irdma_unmap_vm_page_list(hw, pg_dma, i);
return -ENOMEM;
}
Thanks,
Zhu Yanjun
>> Another problem, after folio is used, I want to know the performance after
>> folio is implemented.
>>
>> How to make tests to get the performance?
> You know what you're working on ... I wouldn't know how best to test
> your code.
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