Messages in this thread |  | | From | Dan Williams <> | Date | Thu, 17 Aug 2017 14:59:20 -0700 | Subject | Re: [HMM-v25 00/19] HMM (Heterogeneous Memory Management) v25 |
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On Thu, Aug 17, 2017 at 2:55 PM, Jerome Glisse <jglisse@redhat.com> wrote: > On Thu, Aug 17, 2017 at 02:39:16PM -0700, Andrew Morton wrote: >> On Wed, 16 Aug 2017 20:05:29 -0400 J__r__me Glisse <jglisse@redhat.com> wrote: >> >> > Heterogeneous Memory Management (HMM) (description and justification) >> >> The patchset adds 55 kbytes to x86_64's mm/*.o and there doesn't appear >> to be any way of avoiding this overhead, or of avoiding whatever >> runtime overheads are added. > > HMM have already been integrated in couple of Red Hat kernel and AFAIK there > is no runtime performance issue reported. Thought the RHEL version does not > use static key as Dan asked. > >> >> It also adds 18k to arm's mm/*.o and arm doesn't support HMM at all. >> >> So that's all quite a lot of bloat for systems which get no benefit from >> the patchset. What can we do to improve this situation (a lot)? > > I will look into why object file grow so much on arm. My guess is that the > new migrate code is the bulk of that. I can hide the new page migration code > behind a kernel configuration flag.
Shouldn't we completely disable all of it unless there is a driver in the kernel that selects it?
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