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SubjectRe: [PATCH v5 1/2] memory_hotplug: Free pages as higher order
On 2018-10-10 13:37, Oscar Salvador wrote:
> On Fri, Oct 05, 2018 at 01:40:05PM +0530, Arun KS wrote:
>> When free pages are done with higher order, time spend on
>> coalescing pages by buddy allocator can be reduced. With
>> section size of 256MB, hot add latency of a single section
>> shows improvement from 50-60 ms to less than 1 ms, hence
>> improving the hot add latency by 60%. Modify external
>> providers of online callback to align with the change.
>
> Hi Arun, out of curiosity:
>
> could you please explain how exactly did you mesure the speed
> improvement?

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index e379e85..2416136 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -690,9 +690,13 @@ static int online_pages_range(unsigned long
start_pfn, unsigned long nr_pages,
void *arg)
{
unsigned long onlined_pages = *(unsigned long *)arg;
+ u64 t1, t2;

+ t1 = local_clock();
if (PageReserved(pfn_to_page(start_pfn)))
onlined_pages = online_pages_blocks(start_pfn,
nr_pages);
+ t2 = local_clock();
+ trace_printk("time spend = %llu us\n", (t2-t1)/(1000));

online_mem_sections(start_pfn, start_pfn + nr_pages);

Regards,
Arun

>
> Thanks

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