On 2024/4/5 12:53, Barry Song wrote:
On Thu, Apr 4, 2024 at 2:47 AM Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> wrote:Commit 44042b449872 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists") extends the PCP allocator to store THP pages, and it determines whether to cache THP pags in PCP by comparing with pageblock_order. But the pageblock_order is not always equal to THP order, it might also be MAX_PAGE_ORDER, which could prevent PCP from caching THP pages. Therefore, using HPAGE_PMD_ORDER instead to determine the need for caching THP for PCP can fix this issue Fixes: 44042b449872 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists") Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>LGTM, Reviewed-by: Barry Song <baohua@xxxxxxxxxx> In the context of using mTHP, perhaps there arises a need for PCP allocation for frequently requested mTHP orders. These orders typically exceed PAGE_ALLOC_COSTLY_ORDER but are smaller than HPAGE_PMD_ORDER.
Yes, I have also considered this, but haven't found some time to do more investigation and run some benchmarks.:) May be we can create a new thread to talk about this first.
