Messages in this thread | | | Date | Sun, 7 Jun 2020 17:11:16 +0100 | From | Russell King - ARM Linux admin <> | Subject | Re: ARM: vmsplit 4g/4g |
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On Sun, Jun 07, 2020 at 06:29:32PM +0530, afzal mohammed wrote: > Hi, > > On Sat, May 16, 2020 at 09:35:57AM +0200, Arnd Bergmann wrote: > > On Sat, May 16, 2020 at 8:06 AM afzal mohammed <afzal.mohd.ma@gmail.com> wrote: > > > > Okay, so the conclusion i take is, > > > 1. VMSPLIT 4G/4G have to live alongside highmem > > > 2. For user space copy, do pinning followed by kmap > > > Right, though kmap_atomic() should be sufficient here > > because it is always a short-lived mapping. > > get_user_pages_fast() followed by kmap_atomic() & then memcpy() seems > to work in principle for user copy.
Have you done any performance evaluation of the changes yet? I think it would be a good idea to keep that in the picture. If there's any significant regression, then that will need addressing.
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