Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1449703

Re: [PATCH 05/32] x86/intel_rdt: Implement scheduling support for Intel RDT

Show all headers | View raw

On Mon, Jul 25, 2016 at 11:31:24AM -0500, Nilay Vaish wrote:
> I was thinking more about this software caching of CLOSids.  How
> likely do you think these CLOSids would be found cached?  I think the
> software cache would be very infrequently accessed, so it seems you
> are likely to miss these in all levels of cache hierarchy and more
> likely to have to fetch these from the main memory, which itself might
> cost ~250 cycles.

We need to avoid reading the PQR_ASSOC MSR (which would cost far
more than 250 cycles).  Life is complicated here because this
MSR contains the CLOSID in the upper half, and the RMID (owned
by the perf code to measure cache occupancy and memory bandwidth)
in the lower half.

I've wondered whether it would be possible to include both the
CLOSID and the RMID in either the task or thread struct (in some
spot that was likely to be pulled into cache by access to adjacent
members during context switch).  This would smooth the path in
context switch (since we can look at the values from the previous
process and compare them to the ones for the new process to see
whether we need to do the wrmsr()).  But it likely needs a bunch
of other changes to update the values when a process migrates
between cpus to get the closid precedence that tglx requires.

-Tony

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 00/32] Enable Intel Resource Allocation in Resource Director Technology  "Fenghua Yu" <fenghua.yu@intel.com> - 2016-07-13 00:10 +0200
  [PATCH 06/32] x86/intel_rdt: Hot cpu support for Cache Allocation "Fenghua Yu" <fenghua.yu@intel.com> - 2016-07-13 00:10 +0200
    Re: [PATCH 06/32] x86/intel_rdt: Hot cpu support for Cache  Allocation Thomas Gleixner <tglx@linutronix.de> - 2016-07-13 11:30 +0200
      Re: [PATCH 06/32] x86/intel_rdt: Hot cpu support for Cache  Allocation Shivappa Vikas <vikas.shivappa@linux.intel.com> - 2016-07-21 21:50 +0200
    Re: [PATCH 06/32] x86/intel_rdt: Hot cpu support for Cache Allocation David Carrillo-Cisneros <davidcc@google.com> - 2016-07-14 02:50 +0200
      RE: [PATCH 06/32] x86/intel_rdt: Hot cpu support for Cache  Allocation "Yu, Fenghua" <fenghua.yu@intel.com> - 2016-07-15 01:00 +0200
  [PATCH 19/32] sched.h: Add rg_list and rdtgroup in task_struct "Fenghua Yu" <fenghua.yu@intel.com> - 2016-07-13 00:10 +0200
    Re: [PATCH 19/32] sched.h: Add rg_list and rdtgroup in task_struct Thomas Gleixner <tglx@linutronix.de> - 2016-07-13 15:10 +0200
      RE: [PATCH 19/32] sched.h: Add rg_list and rdtgroup in task_struct "Yu, Fenghua" <fenghua.yu@intel.com> - 2016-07-13 20:00 +0200
    Re: [PATCH 19/32] sched.h: Add rg_list and rdtgroup in task_struct Nilay Vaish <nilayvaish@gmail.com> - 2016-07-28 08:00 +0200
  [PATCH 21/32] x86/intel_rdt.h: Header for inter_rdt.c "Fenghua Yu" <fenghua.yu@intel.com> - 2016-07-13 00:10 +0200
    Re: [PATCH 21/32] x86/intel_rdt.h: Header for inter_rdt.c Nilay Vaish <nilayvaish@gmail.com> - 2016-07-28 16:10 +0200
  [PATCH 12/32] x86/intel_rdt: Hot cpu update for code data prioritization "Fenghua Yu" <fenghua.yu@intel.com> - 2016-07-13 00:10 +0200
  [PATCH 27/32] x86/intel_rdt_rdtgroup.c: Implement rscctrl file system commands "Fenghua Yu" <fenghua.yu@intel.com> - 2016-07-13 00:10 +0200
  [PATCH 30/32] x86/intel_rdt_rdtgroup.c: Process schemas input from rscctrl interface "Fenghua Yu" <fenghua.yu@intel.com> - 2016-07-13 00:10 +0200
    Re: [PATCH 30/32] x86/intel_rdt_rdtgroup.c: Process schemas input  from rscctrl interface David Carrillo-Cisneros <davidcc@google.com> - 2016-07-14 02:50 +0200
      RE: [PATCH 30/32] x86/intel_rdt_rdtgroup.c: Process schemas input  from rscctrl interface "Yu, Fenghua" <fenghua.yu@intel.com> - 2016-07-14 08:20 +0200
      Re: [PATCH 30/32] x86/intel_rdt_rdtgroup.c: Process schemas input  from rscctrl interface Thomas Gleixner <tglx@linutronix.de> - 2016-07-14 08:20 +0200
      RE: [PATCH 30/32] x86/intel_rdt_rdtgroup.c: Process schemas input  from rscctrl interface "Yu, Fenghua" <fenghua.yu@intel.com> - 2016-07-14 08:40 +0200
  [PATCH 02/32] x86/intel_rdt: Add support for Cache Allocation detection "Fenghua Yu" <fenghua.yu@intel.com> - 2016-07-13 00:10 +0200
    Re: [PATCH 02/32] x86/intel_rdt: Add support for Cache Allocation detection Nilay Vaish <nilayvaish@gmail.com> - 2016-07-26 21:10 +0200
  [PATCH 01/32] x86/intel_rdt: Cache Allocation documentation "Fenghua Yu" <fenghua.yu@intel.com> - 2016-07-13 00:10 +0200
  [PATCH 28/32] x86/intel_rdt_rdtgroup.c: Read and write cpus "Fenghua Yu" <fenghua.yu@intel.com> - 2016-07-13 00:10 +0200
  [PATCH 03/32] x86/intel_rdt: Add Class of service management "Fenghua Yu" <fenghua.yu@intel.com> - 2016-07-13 00:20 +0200
  [PATCH 04/32] x86/intel_rdt: Add L3 cache capacity bitmask management "Fenghua Yu" <fenghua.yu@intel.com> - 2016-07-13 00:20 +0200
    Re: [PATCH 04/32] x86/intel_rdt: Add L3 cache capacity bitmask  management Marcelo Tosatti <mtosatti@redhat.com> - 2016-07-22 23:10 +0200
      Re: [PATCH 04/32] x86/intel_rdt: Add L3 cache capacity bitmask  management "Luck, Tony" <tony.luck@intel.com> - 2016-07-22 23:50 +0200
        Re: [PATCH 04/32] x86/intel_rdt: Add L3 cache capacity bitmask  management Marcelo Tosatti <mtosatti@redhat.com> - 2016-07-26 04:20 +0200
          Re: [PATCH 04/32] x86/intel_rdt: Add L3 cache capacity bitmask  management "Luck, Tony" <tony.luck@intel.com> - 2016-07-26 05:20 +0200
          Re: [PATCH 04/32] x86/intel_rdt: Add L3 cache capacity bitmask  management Shivappa Vikas <vikas.shivappa@linux.intel.com> - 2016-07-26 19:10 +0200
  [PATCH 05/32] x86/intel_rdt: Implement scheduling support for Intel RDT "Fenghua Yu" <fenghua.yu@intel.com> - 2016-07-13 00:20 +0200
    Re: [PATCH 05/32] x86/intel_rdt: Implement scheduling support for  Intel RDT Nilay Vaish <nilayvaish@gmail.com> - 2016-07-25 18:30 +0200
    Re: [PATCH 05/32] x86/intel_rdt: Implement scheduling support for  Intel RDT Nilay Vaish <nilayvaish@gmail.com> - 2016-07-25 18:40 +0200
      Re: [PATCH 05/32] x86/intel_rdt: Implement scheduling support for  Intel RDT "Luck, Tony" <tony.luck@intel.com> - 2016-07-25 20:10 +0200
        Re: [PATCH 05/32] x86/intel_rdt: Implement scheduling support for  Intel RDT David Carrillo-Cisneros <davidcc@google.com> - 2016-07-26 00:50 +0200

csiph-web