Re: [RFC PATCH v4 00/13] ktask: multithread CPU-intensive kernel work

Daniel Jordan
2018-11-06T02:20:24Z

Hi Zi,

On Mon, Nov 05, 2018 at 01:49:14PM -0500, Zi Yan wrote:
> On 5 Nov 2018, at 11:55, Daniel Jordan wrote:
>
> Do you think if it makes sense to use ktask for huge page migration (the data
> copy part)?

It certainly could.

> I did some experiments back in 2016[1], which showed that migrating one 2MB page
> with 8 threads could achieve 2.8x throughput of the existing single-threaded method.
> The problem with my parallel page migration patchset at that time was that it
> has no CPU-utilization awareness, which is solved by your patches now.

Did you run with fewer than 8 threads? I'd want a bigger speedup than 2.8x for
8, and a smaller thread count might improve thread utilization.

It would be nice to multithread at a higher granularity than 2M, too: a range
of THPs might also perform better than a single page.

Thanks for your comments.

> [1]https://lkml.org/lkml/2016/11/22/457