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Re: [RESEND PATCH 0/3] mm: Add cache coloring mechanism

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On 08/24/2017 06:08 PM, Dave Hansen wrote:
> On 08/24/2017 05:47 AM, Vlastimil Babka wrote:
>> So the obvious question, what about THPs? Their size should be enough to
>> contain all the colors with current caches, no? Even on KNL I didn't
>> find more than "32x 1 MB 16-way L2 caches". This is in addition to the
>> improved TLB performance, which you want to get as well for such workloads?
> 
> The cache in this case is "MCDRAM" which is 16GB in size.  It can be
> used as normal RAM or a cache.  This patch deals with when "MCDRAM" is
> in its cache mode.

Hm, 16GB direct mapped, that means 8k colors for 2MB THP's. Is that
really practical? Wouldn't such workload use 1GB hugetlbfs pages? Then
it's still 16 colors to manage, but could be done purely in userspace
since they should not move in physical memory and userspace can control
where to map each phase in the virtual layout.

> It's described in the "Memory Modes" slide here:
> 
>> http://www.nersc.gov/users/computational-systems/cori/configuration/knl-processor-modes/
> 

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[RESEND PATCH 0/3] mm: Add cache coloring mechanism Łukasz Daniluk <lukasz.daniluk@intel.com> - 2017-08-23 12:10 +0200
  [RESEND PATCH 3/3] mm: Add helper rbtree to search for next cache color Łukasz Daniluk <lukasz.daniluk@intel.com> - 2017-08-23 12:10 +0200
  [RESEND PATCH 2/3] mm: Add page colored allocation path Łukasz Daniluk <lukasz.daniluk@intel.com> - 2017-08-23 12:10 +0200
    Re: [RESEND PATCH 2/3] mm: Add page colored allocation path Dave Hansen <dave.hansen@intel.com> - 2017-08-23 16:00 +0200
  [RESEND PATCH 1/3] mm: move free_list selection to dedicated functions Łukasz Daniluk <lukasz.daniluk@intel.com> - 2017-08-23 12:10 +0200
  Re: [RESEND PATCH 0/3] mm: Add cache coloring mechanism Vlastimil Babka <vbabka@suse.cz> - 2017-08-24 14:50 +0200
    Re: [RESEND PATCH 0/3] mm: Add cache coloring mechanism Dave Hansen <dave.hansen@intel.com> - 2017-08-24 18:10 +0200
      Re: [RESEND PATCH 0/3] mm: Add cache coloring mechanism Vlastimil Babka <vbabka@suse.cz> - 2017-08-25 11:10 +0200
        Re: [RESEND PATCH 0/3] mm: Add cache coloring mechanism Dave Hansen <dave.hansen@intel.com> - 2017-08-25 15:20 +0200

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