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Intel vs AMD DragonFly 2.11 parallel kernel build tests

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
Date: Thu, 12 May 2011 16:00:31 -0700 (PDT)

		Intel vs AMD DragonFly 2.11 parallel kernel build tests

    PhenomIIx6 1090T 3.2GHz w/turbo, not overclocked (6 cores)
    Intel-i7 2600K   3.4GHz w/turbo, not overclocked (4 cores, 2x HT)

    Tests done with 64-bit kernel, sources fully cached in tmpfs
    (i.e. no disk or network activity worth mentioning during the tests)

    AMD		Intel		Test
    ----	----		----
    71 seconds	50 seconds	Buildkernel -j12 KERNCONF=X86_64_GENERIC \
    183 seconds 144 seconds	Buildkernel -j1 w/same parameters
    unavail	33W		Watt meter idle				(note1)
    unavail	92W		Watt meter full load (buildkernel -j12) (note1)
    247648K	569115K		Openssl speed -elapsed -evp aes-128-cbc (note2)
    108567K	110798K		Openssl speed -elapsed -evp aes-128-ecb (note2)
    unavail	6322 Mbits/s	Cryptotest -a aes 102400 8192
    135ns	184ns		System call overhead getuid()

    note 1: The i7 box I just built has a Seasonic gold (87%+ efficiency)
	    400W power supply in it and my PhenonIIx6 has a generic PSU
	    in it that's probably more around 75-80%.  The phenomII box
	    eats around 50-60W idle but I don't know how much better it
	    would be with a good PSU in it, so grain-of-salt.

	    Still, 33W idle for a high-end Intel consumer box is very

    note 2: aes-128-cbc on the intel uses the AESNI instructions available
	    on the SandyBridge.  The -ecb test does not.  The phenom II does
	    not have these instructions so we can see that cpu-bound core
	    logic loops are actually fairly close between the two cpus.
	    These tests were for 8192 byte buffers.

    For the cpu tests I build the kernel core without modules, which is a
    fully parallel build (building modules is not), so -j12 saturates all
    available cpus and tests the turbo fallback.

    The -j1 test effectively tests single-core performance for the same
    workload, and being just one core it will presumably run at max-turbo
    (both the AMD and Intel cpus in this test implement core turbo).

    AMD		Intel		Simple memory bw test (/usr/src/test/mbwtest.c)
    14 GByte/s	18 GByte/s	L2
    8.1 GByte/s	14 GBytes/s	L3
    5.2 GByte/s	11 GByte/s	Main memory

    Use DDR3-1333.  Memory timings don't appear to make much of a difference
    at all, even going from 9-9-9 to 7-7-7 on the i7 box.

    The PhenomIIx7 box is also running w/ECC memory.  There is no ECC option
    available for Intel, but I don't think the difference would be all that
    great and we already knew that Intel's memory bandwidth was very
    impressive on the SandyBridge chips.


    * The Intel-i7 2600K crushes the PhenomIIx6 1090T under full parallel
      load (4 cores x 2 hyperthreads each vs 6 cores) by upwards of 30%.

    * The Intel also beats the 1090T on the single-core load by 21%

    * The Intel Sandybridge cpus have AESNI crypto instructions.  The
      first crypto test (aes-128-cbc) uses those instructions, the second
      does not.  Without the instructions the instruction loops running the
      crypto logic are fairly close between AMD and Intel, and with the
      instructions Intel is 2.3x faster.

      Also note that this is per-cpu core, so we are talking approximately
      6.3 GBits/sec x 4 (at least) for crypted disks, since DragonFly will
      use multiple cores for the crypto.

    * Sandybridge likely edges out AMD on power savings now, certainly the
      33W idle consumption is very good.  I don't have any good comparison
      available there because my PSUs are different.  With a crappy PSU the
      AMD test box eats ~50-60W idle.  But even if we give the PSU another
      10% efficiency we are still talking 45W-54W.  Intel is gonna beat it.

    * The simple system call overhead test and the non-accelerated crypto
      test shows that AMD does do well in some areas, but the crushing they
      take in the compiler test shows the limitations of on-die caches.

    * There is no point running I/O tests.  AMD actually has better support
      for 6GBit/sec SATA-III than Intel on their lower-end offerings from
      a price standpoint.  Either way today's modern cpus have no trouble
      saturating even several SATA-III ports.

    There is just one downside to the Intel-i7.  Well, two if you count the
    price.  The downside that really gets my goat though is the lack of ECC
    memory support on their consumer cpu line.  I mean, COME ON INTEL!  When
    you stuff 16G of ram into a consumer box having ECC is probably going to
    be a good idea.  Gamers might not care, and most 'consumers' might not
    notice, but anyone who cares about data integrity will care.

    Other than that I would happily replace all my servers w/Sandybridge
    today.  As it stands though I don't actually need a ton of horsepower on
    the servers.  Our build boxes are the only things that really need the
    horsepower of a Sandybridge.  The reduced power consumption is very
    provacative but it's a non-starter without ECC.

    And AMD has saved me a ton of money over the years with their AM2+/AM3
    socket compatibility.  I've gone through three major generational cycles
    on cpus with the same mobos just by buying a new cpu.  Intel suffers
    from too much socketmania and it gets expensive when you have to replace
    the mobo, the memory, AND the cpu whenever you upgrade.

    So for the moment I am willing to wait for AMD to come out with
    something better.  It doesn't have to beat Intel, but it does have to
    get within shouting distance and 30% aint within shouting distance.
    Even factoring in a current higher-end AMD cpu we still aren't going to
    get more than another 7% improvement (23% is still too much).  If AMD can
    get within 15% in the next year or so I'll happily stick with them on
    principle.  But if they can't then I will grudgingly pay Intel's premium.

    (And, p.s. this is why I invest in Intel and not AMD.  Intel has the
    monopoly and intentionally keeps AMD as a poor second cousin to keep
    the anti-trust hounds at bay.  Sorry AMD, I love you but I can only
    support you in some ways :-( )

					Matthew Dillon 

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