Huge pages part 5: A deeper look at TLBs and costs [LWN.net]

Huge pages part 5: A deeper look at TLBs and costs

Posted Mar 26, 2010 1:38 UTC (Fri) by sync (guest, #39669)
In reply to: Huge pages part 5: A deeper look at TLBs and costs by ken
Parent article: Huge pages part 5: A deeper look at TLBs and costs

Atom?
Mine gives 7 cycle too

My old Athlon XP 2000MHz has 5 cycles!

Running calibrator with size 13631488: 5 cycles 2.57 ns
Running calibrator with size 17563648: 5 cycles 2.59 ns matched 1 times
Running calibrator with size 21495808: 5 cycles 2.58 ns matched 2 times
Running calibrator with size 25427968: 5 cycles 2.57 ns matched 3 times

TLB_MISS_LATENCY_TIME=2.57
TLB_MISS_LATENCY_CYCLES=5
TLB_MISSES_COST_ONE_SECOND=400000000

And many thanks to Mel for this wonderful series.

(Log in to post comments)

Huge pages part 5: A deeper look at TLBs and costs

Posted Mar 31, 2010 17:31 UTC (Wed) by jzbiciak (✭ supporter ✭, #5246) [Link]

On Athlons, at least, there's a hardware table walk and a two-level TLB structure. It wouldn't surprise me to find out that the 5 cycle number you report is the average cost of missing the L1 TLB (frequent, fast) and L2 TLB (less frequent, but slower).