AMD athlon 64 Manuale Utente
28
Analysis and Recommendations
Chapter 3
40555
Rev. 3.00
June 2006
Performance Guidelines for AMD Athlon™ 64 and AMD Opteron™
ccNUMA Multiprocessor Systems
ccNUMA Multiprocessor Systems
Figure 8.
Crossfire 1 Hop-1 Hop Case vs No Crossfire 1 Hop-1 Hop Case under a
Very High Background Load (High Subscription)
Next, we increase the number of background threads to six, running on:
•
Node 0 (Core 1)
•
Node 1 (Core 1)
•
Node 2 (Cores 0 and 1)
•
Node 3 (Cores 0 and 1)
Each of these background threads reads a local 64 MB array and the rate of memory demand of each
thread is very high. A very high rate of memory demand implies that each of the background threads
is demanding a memory bandwidth of 4GB/s, as shown in Table 1 on page 16.
thread is very high. A very high rate of memory demand implies that each of the background threads
is demanding a memory bandwidth of 4GB/s, as shown in Table 1 on page 16.
No free cores are left in the system. This the fully subscribed condition.
As shown in Figure 9 on page 29, when the background load and level subscription are increased to
the maximum possible, the no crossfire case becomes slower than the crossfire case.
the maximum possible, the no crossfire case becomes slower than the crossfire case.
VERY HIGH: Total Time for both threads (write-write)
158%
186%
195%
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
0.0.w.0 1.0.w.1 (0 Hops) (0 Hops)
0.0.w.1 1.0.w.3 (1 Hops) (1 Hops)
0.0.w.1 1.0.w.0 (1 Hops) (1 Hops)
0 Hop
0 Hop
0 Hop
1 Hop
1 Hop
1 Hop
NO
Xfire
1 Hop
1 Hop
1 Hop
Xfire