On 11.03.22 10:01, Bibo Mao wrote:
> collapse huge page is slow, specially when khugepaged daemon runs
> on different numa node with that of huge page. It suffers from
> huge page copying across nodes, also cache is not used for target
> node. With this patch, khugepaged daemon switches to the same numa
> node with huge page. It saves copying time and makes use of local
> cache better.
Hi,
just the usual question, do you have any performance numbers to back
your claims (e.g., "is slow, specially when") and proof that this patch
does the trick?
>
> Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
> ---
> mm/khugepaged.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 131492fd1148..460c285dc974 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -116,6 +116,7 @@ struct khugepaged_scan {
> struct list_head mm_head;
> struct mm_slot *mm_slot;
> unsigned long address;
> + int node;
> };
>
> static struct khugepaged_scan khugepaged_scan = {
> @@ -1066,6 +1067,7 @@ static void collapse_huge_page(struct mm_struct *mm,
> struct vm_area_struct *vma;
> struct mmu_notifier_range range;
> gfp_t gfp;
> + const struct cpumask *cpumask;
We tend to stick to reverse Christmas tree format as good as possible.
>
> VM_BUG_ON(address & ~HPAGE_PMD_MASK);
>
> @@ -1079,6 +1081,13 @@ static void collapse_huge_page(struct mm_struct *mm,
> * that. We will recheck the vma after taking it again in write mode.
> */
> mmap_read_unlock(mm);
> +
> + /* sched to specified node before huage page memory copy */
s/huage/huge/
> + cpumask = cpumask_of_node(node);
> + if ((khugepaged_scan.node != node) && !cpumask_empty(cpumask)) {
> + set_cpus_allowed_ptr(current, cpumask);
> + khugepaged_scan.node = node;
> + }
> new_page = khugepaged_alloc_page(hpage, gfp, node);
> if (!new_page) {
> result = SCAN_ALLOC_HUGE_PAGE_FAIL;
> @@ -2380,6 +2389,7 @@ int start_stop_khugepaged(void)
> kthread_stop(khugepaged_thread);
> khugepaged_thread = NULL;
> }
> + khugepaged_scan.node = NUMA_NO_NODE;
> set_recommended_min_free_kbytes();
> fail:
> mutex_unlock(&khugepaged_mutex);
--
Thanks,
David / dhildenb
