Archive for April, 2010

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Quick Take: IBM Tops VMmark, Crushes Record with 4P Nehalem-EX

April 7, 2010

It was merely a matter of time before one of the new core-rich titans – the Intel’s 8-core “Beckton” Nehalem-EX (Xeon 7500) or AMD’s 12-core “Magny-Cours” (Opteron 6100) – was to make a name for itself on VMware’s VMmark benchmark. Today, Intel draws first blood in the form of an 4-processor, 32-core, 64-thread, monster from IBM: the x3850 X5 running four Xeon X7560 (2.266GHz – 2.67GHz w/turbo, 130W TDP, each) and 384GB of DDR3-1066 low-power registered DIMMs. Weighing-in at 70.78@48 tiles, the 4P IBM System x3850 handily beats the next highest system – the 48-core DL785 G5 which set the record of 53.73@35 tiles back in August, 2009 – and bests it by over 30%.

At $3,800+ per socket for the tested Beckton chip, this is no real 2P alternative. In fact, a pair of Cisco UCS B250 M2 blades will get 52 tiles running for much less money. Looking at processor and memory configurations alone, this is a $67K+ enterprise server, resulting in a moderately-high $232/VM price point for the IBM x3850 X5.

SOLORI’s Take: The most interesting aspect of the EX benchmark is its clock-adjusted scaling factor: between 70% and 91% versus a 2P/8-core Nehalem-EP reference (Cisco UCS, B200 M1, 25.06@17 tiles). The unpredictable nature of Intel’s “turbo” feature – varying with thermal loads and per-core conditions – makes an exact clock-for-clock comparison difficult. However, if the scaling factor is 90%, the EX blows away our previous expectations about the platform’s scalability. Where did we go wrong when we predicted a conservative 44@39 tiles? We’re looking at three things: (1) a bad assumption about the effectiveness of “turbo” in the EP VMmark case (setting Ref_EP_Clock to 3.33 GHz), and (2) underestimating EX’s scaling efficiency (assumed 70%), (3) assuming a 2.26GHz clock for EX.

Chosing our minimum QPI/HT3 scalability factor of 75%, the predicted performance was derived this way from HP Proliant BL490 G6 as a baseline:

Est. Tiles = EP_Tiles_per_core( 2.13 ) * 32 cores * Scaling_Efficiency( 75% ) * EX_Clock( 2.26 ) / EP_Clock( 2.93 ) = 39 tiles

Est. Score = Est_Tiles( 40 ) * EP_Score_per_Tile( 1.43 ) * Est_EX_Clock( 2.26 ) / Ref_EP_Clock( 2.93 ) = 44.12

Est. Nehalem-EX VMmark -> 44.12@39 tiles

Correcting for the as-tested clock/turbo numbers, and using AMD’s 2P-to-4P VMmark scaling efficiency of 83%, and shifting to the new UCS baseline (with newer ESX version) the Nehalem-EX prediction factors to:

Est. Tiles = EP_Tiles_per_core( 2.13 ) * 32 cores * Scaling_Efficiency( 83% ) * EX_Clock( 2.67 ) / EP_Clock( 2.93 ) = 51 tiles

Est. Score = Est_Tiles( 51 ) * EP_Score_per_Tile( 1.47 ) * Est_EX_Clock( 2.67 ) / Ref_EP_Clock( 2.93 ) = 68.32

Est. Nehalem-EX VMmark -> 68.3@51 tiles

Clearly, this approach either overestimates the scaling efficiency or underestimates the “turbo” mode. IBM claims that a 2.93 GHz “turbo” setting is viable where Intel suggests 2.67 GHz is the maximum, so there is a source of potential bias. Looking at the tiles-per-core ratio of the VMmark result, the Nehalem-EX drops from 2.13 tiles per core on EP/2P platforms to 1.5 tiles per core on EX/4P platforms – about a 30% drop in per-core loading efficiency. That indicator matches well with our initial 75% scaling efficiency moving from 2P to 4P – something that AMD demonstrated with Istanbul last August. Given the high TDP of EX and IBM’s 2.93 GHz “turbo” specification, it’s possible that “turbo” is adding clock cycles (and power consumption) and compensating for a “lower” scaling efficiency than we’ve assumed. Looking at the same estimation with 2.93GHz “clock” and 71% efficiency (1.5/2.13), the numbers fall in line with VMmark:

Est. Tiles = EP_Tiles_per_core( 2.13 ) * 32 cores * Scaling_Efficiency( 71% ) * EX_Clock( 2.93 ) / EP_Clock( 2.93 ) = 48 tiles

Est. Score = Est_Tiles( 48 ) * EP_Score_per_Tile( 1.47 ) * Est_EX_Clock( 2.93 ) / Ref_EP_Clock( 2.93 ) = 70.56

Est. Nehalem-EX VMmark -> 70.56@48 tiles

This give us a good basis for evaluating 2P vs. 4P Nehalem systems: scaling factor of 71% and capable of pushing clock towards the 3GHz mark within its thermal envelope. Both of these conclusions fit typical 2P-to-4P norms and Intel’s process history.

SOLORI’s 2nd Take: So where does that leave AMD’s newest 12-core chip? To date, no VMmark exists for AMD’s Magny-Cours, and AMD chips tend not to do as well in VMmark as their Intel peers do to the benchmarks SMT-friendly loads. However, we can’t resist using the same analysis against AMD/MC’s 2.4GHz Opteron 6174SE (theoretical) using the 2P HP DL385 G6 as a baseline for core loading and the HP DL785 G6 for tile performance (best of the best cases):

Est. Tiles = HP_Tiles_per_core( 0.92 ) * 48 cores * Scaling_Efficiency( 83% ) * MC_Clock( 2.3 ) / HP_Clock( 2.6 ) = 33 tiles

Est. Score = Est_Tiles( 34 ) * HP_Score_per_Tile( 1.54 ) * Est_MC_Clock( 2.3 ) / Ref_HP_Clock( 2.8 ) = 41.8

Est. 4P Magny-Cours VMmark -> 41.8@33 tiles

That’s nowhere near good enough to top the current 8P, 48-core Istanbul VMmark at 53.73@35 tiles, so we’ll likely have to wait for faster 6100 parts to see any new AMD records. However, assuming AMD’s proposition is still “value 4P” so about 200 VM’s at under $18K/server gets you around $90/VM or less.