On 9 Jan 2025, at 6:47, Shivank Garg wrote:
> On 1/3/2025 10:54 PM, Zi Yan wrote:
>> This is a preparatory patch that enables batch copying for folios
>> undergoing migration. By enabling batch copying the folio content, we can
>> efficiently utilize the capabilities of DMA hardware or multi-threaded
>> folio copy. It also adds MIGRATE_NO_COPY back to migrate_mode, so that
>> folio copy will be skipped during metadata copy process and performed
>> in a batch later.
>>
>> Currently, the folio move operation is performed individually for each
>> folio in sequential manner:
>> for_each_folio() {
>> Copy folio metadata like flags and mappings
>> Copy the folio content from src to dst
>> Update page tables with dst folio
>> }
>>
>> With this patch, we transition to a batch processing approach as shown
>> below:
>> for_each_folio() {
>> Copy folio metadata like flags and mappings
>> }
>> Batch copy all src folios to dst
>> for_each_folio() {
>> Update page tables with dst folios
>> }
>>
>> dst->private is used to store page states and possible anon_vma value,
>> thus needs to be cleared during metadata copy process. To avoid additional
>> memory allocation to store the data during batch copy process, src->private
>> is used to store the data after metadata copy process, since src is no
>> longer used.
>>
>> Originally-by: Shivank Garg <shivankg@xxxxxxx>
>> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
>> ---
>
> Hi Zi,
>
> Please retain my Signed-off-by for future posting of batch page migration
> patchset.
>
> I think we can separate out the MIGRATE_NO_COPY support into separate patch.
Sure. Will change them in the next version.
Best Regards,
Yan, Zi
