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Intel Iris Pro Linux Performance Doubles With Driver Upgrades

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  • #16
    Originally posted by guido12 View Post
    Any thoughts on Windows 8's deferred thread execution technique? Does this really improve battery life without causing performance issues? If so, are there any work to do something similar In Linux?

    Linux either has, or is working on, process deferrment/grouping through a power-aware scheduler. In the meantime we've had deferrable timers since 2.6.21 which lets the scheduler defer certain processes wakeup requests until the next wakeup caused by an event with a non-deferrable timer.
    As far as the cpu is concerned, the last thing we really need is to completely get rid of ticks (we look to be quite close to that with the recent 1hz kernel).
    Last edited by liam; 09-21-2013, 06:30 PM.


    • #17
      Originally posted by curaga View Post
      Well clearly the edram is not properly used. Intel folks, is it supposed to be working?
      Michael's article (pushed today) which summarizes his experience with the Galago Ultrapro laptop reminded me of something.

      Specifically, I was initially thinking about the 4600 vs iris pro 5200 results in light of the fact that:
      • they were done using a 3.11 kernel on Ubuntu
      • kernel 3.12 is supposed to enable the eDRAM on the iris pro 5200
      • the recent kerfuffle about 3.12 benchmark results (initially w.r.t. for radeon) which exposed (at least, to me) that Ubuntu is currently not using the p-state driver for those intel CPUs for which it supports ... the consequence of that being that (under Ubuntu) the Haswell, IVB and SNB parts would be using the acpi_cpufreq ... and because Phoronix tests OOTB, the cpufreq ondemand governor was being utilized as opposed to the performance gov. ... the cpufreq ondemand governor change in the 3.12 kernel, as various Phoronix testing showed, evidently alleviates the previous restraining impact it (the ondemand gov behaviour) was having on gpu benchmark performance in some cases (notably for systems with gpu headroom but whom were being artificially cpu bound)
      In the APUs not afftected thread, I drew attention to the fact that even a relatively gpu bound adapter showed some benefit from the change. I further speculated that higher end iGPUs, such as the Intel iris pro, might also see better results on kernel 3.12 (when testing under Ubuntu). One would expect that the 5200's case for that would only be strengthened by the enabling of the eDRAM in the 3.12 kernel. And if you follow all that, it means that there might be an even greater disparity between the 4600 & iris pro results then what was originally reported back in that article linked above.

      However, looking back even further, to the parent article for this thread, I see that:
      • its benchmarks were also carried out using Ubuntu ... meaning (in the case of Phoronix) no p-state, but acpi_cpufreq with ondemand
      • a 3.12 kernel was used ... meaning that:
        - the ondemand gov would no longer negatively impact testing and
        - the eDRAM should have been enabled
      And yet ... the benchmark results under 3.12 were actually tending to be a little below those seen under the 3.11 kernel

      So, yes, indeed, what is the story with the eDRAM ?
      Last edited by Tyler_K; 10-20-2013, 07:00 PM.


      • #18
        these results show that for even low-end Intel "Haswell" HD Graphics 4400 there is a great deal of performance that can be gained from going with DDR3-1600MHz (or higher) memory.
        Indeed! And just imagine what should happen when you add in a bit of eDRAM for an even more powerful adapter like, oh, I don't know, maybe an Iris pro


        • #19
          I read here, the blue sky, a large number of similar machines throttling the CPU and GPU. System76 Galago throttle too pulled out? If so, you may also include a pull out the insert VS GPU benchmark performance tests, the laptop do?