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SubjectRe: [PATCH 0/5] Parallel hugepage migration optimization
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On 23/11/16 03:25, Zi Yan wrote:
> From: Zi Yan <zi.yan@cs.rutgers.edu>
>
> Hi all,
>
> This patchset boosts the hugepage migration throughput and helps THP migration
> which is added by Naoya's patches: https://lwn.net/Articles/705879/.
>
> Motivation
> ===============================
>
> In x86, 4KB page migrations are underutilizing the memory bandwidth compared
> to 2MB THP migrations. I did some page migration benchmarking on a two-socket
> Intel Xeon E5-2640v3 box, which has 23.4GB/s bandwidth, and discover
> there are big throughput gap, ~3x, between 4KB and 2MB page migrations.
>
> Here are the throughput numbers for different page sizes and page numbers:
> | 512 4KB pages | 1 2MB THP | 1 4KB page
> x86_64 | 0.98GB/s | 2.97GB/s | 0.06GB/s
>
> As Linux currently use single-threaded page migration, the throughput is still
> much lower than the hardware bandwidth, 2.97GB/s vs 23.4GB/s. So I parallelize
> the copy_page() part of THP migration with workqueue and achieve 2.8x throughput.
>
> Here are the throughput numbers of 2MB page migration:
> | single-threaded | 8-thread
> x86_64 2MB | 2.97GB/s | 8.58GB/s
>

Whats the impact on CPU utilization? Is there a huge impact?

Balbir Singh.

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