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Re: [v3 0/9] parallelized "struct page" zeroing

From Michal Hocko <mhocko@kernel.org>
Newsgroups linux.kernel
Subject Re: [v3 0/9] parallelized "struct page" zeroing
Date 2017-05-31 18:40 +0200
Message-ID <tNeP8-7dL-13@gated-at.bofh.it> (permalink)
References (4 earlier) <tHv6h-4wd-17@gated-at.bofh.it> <tHGbo-3ia-17@gated-at.bofh.it> <tLqB3-8i8-11@gated-at.bofh.it> <tMrv4-7MV-25@gated-at.bofh.it> <tMSYi-1K4-1@gated-at.bofh.it>
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On Tue 30-05-17 13:16:50, Pasha Tatashin wrote:
> >Could you be more specific? E.g. how are other stores done in
> >__init_single_page safe then? I am sorry to be dense here but how does
> >the full 64B store differ from other stores done in the same function.
> 
> Hi Michal,
> 
> It is safe to do regular 8-byte and smaller stores (stx, st, sth, stb)
> without membar, but they are slower compared to STBI which require a membar
> before memory can be accessed.

OK, so why cannot we make zero_struct_page 8x 8B stores, other arches
would do memset. You said it would be slower but would that be
measurable? I am sorry to be so persistent here but I would be really
happier if this didn't depend on the deferred initialization. If this is
absolutely a no-go then I can live with that of course.

-- 
Michal Hocko
SUSE Labs

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Thread

Re: [v3 0/9] parallelized "struct page" zeroing Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-05-26 18:50 +0200
  Re: [v3 0/9] parallelized "struct page" zeroing Michal Hocko <mhocko@kernel.org> - 2017-05-29 14:00 +0200
    Re: [v3 0/9] parallelized "struct page" zeroing Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-05-30 19:20 +0200
      Re: [v3 0/9] parallelized "struct page" zeroing Michal Hocko <mhocko@kernel.org> - 2017-05-31 18:40 +0200
        Re: [v3 0/9] parallelized "struct page" zeroing David Miller <davem@davemloft.net> - 2017-05-31 19:00 +0200
        Re: [v3 0/9] parallelized "struct page" zeroing Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-06-01 05:40 +0200
          Re: [v3 0/9] parallelized "struct page" zeroing Michal Hocko <mhocko@kernel.org> - 2017-06-01 10:50 +0200

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