1: # PAE and Xen balloon benchmarks #
2:
3: ## Protocol ##
4:
5: Three tests were performed to benchmark the kernel:
6:
7: 1. build.sh runs. The results are those returned by [[!template id=man name="time" section="1"]].
8: 1. hackbench, a popular tool used by Linux to benchmarks thread/process creation time.
9: 1. sysbench, which can benchmark mulitple aspect of a system. Presently, the memory bandwidth, thread creation, and OLTP (online transaction processing) tests were used.
10:
11: All were done three times, with a reboot between each of these tests.
12:
13: The machine used:
14:
15: [[!template id=programlisting text="""
16: # cpuctl list
17: Num HwId Unbound LWPs Interrupts Last change
18: ---- ---- ------------ -------------- ----------------------------
19: 0 0 online intr Sun Jul 11 00:25:31 2010
20: 1 1 online intr Sun Jul 11 00:25:31 2010
21: # cpuctl identify 0
22: cpu0: Intel Pentium 4 (686-class), 2798.78 MHz, id 0xf29
23: cpu0: features 0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR>
24: cpu0: features 0xbfebfbff<PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX>
25: cpu0: features 0xbfebfbff<FXSR,SSE,SSE2,SS,HTT,TM,SBF>
26: cpu0: features2 0x4400<CID,xTPR>
27: cpu0: "Intel(R) Pentium(R) 4 CPU 2.80GHz"
28: cpu0: I-cache 12K uOp cache 8-way, D-cache 8KB 64B/line 4-way
29: cpu0: L2 cache 512KB 64B/line 8-way
30: cpu0: ITLB 4K/4M: 64 entries
31: cpu0: DTLB 4K/4M: 64 entries
32: cpu0: Initial APIC ID 0
33: cpu0: Cluster/Package ID 0
34: cpu0: SMT ID 0
35: cpu0: family 0f model 02 extfamily 00 extmodel 00
36: # cpuctl identify 1
37: cpu1: Intel Pentium 4 (686-class), 2798.78 MHz, id 0xf29
38: cpu1: features 0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR>
39: cpu1: features 0xbfebfbff<PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX>
40: cpu1: features 0xbfebfbff<FXSR,SSE,SSE2,SS,HTT,TM,SBF>
41: cpu1: features2 0x4400<CID,xTPR>
42: cpu1: "Intel(R) Pentium(R) 4 CPU 2.80GHz"
43: cpu1: I-cache 12K uOp cache 8-way, D-cache 8KB 64B/line 4-way
44: cpu1: L2 cache 512KB 64B/line 8-way
45: cpu1: ITLB 4K/4M: 64 entries
46: cpu1: DTLB 4K/4M: 64 entries
47: cpu1: Initial APIC ID 0
48: cpu1: Cluster/Package ID 0
49: cpu1: SMT ID 0
50: cpu1: family 0f model 02 extfamily 00 extmodel 00
51: """]]
52:
53: This machine uses HT - so technically speaking, it is not a true bi-CPU host.
54:
55: ## PAE ##
56:
57: [[build-pae.png]]
58: [[hackbench-pae.png]]
59: [[sysbench-pae.png]]
60:
61: Overall, PAE affects memory performance by a 15-20% ratio; this is particularly noticeable with sysbench and hackbench, where bandwidth and thread/process creation time are all slower.
62:
63: Userland remains rather unaffected, with differences in the 5% range; build.sh -j4 runs approximately 5% slower under PAE, both for native and Xen case.
64:
65: Do not be surprised by the important "user" result for build.sh benchmark in the native vs Xen case. Build being performed with -j4 (4 make sub-jobs in parallel), many processes may run concurrently under i386 native, crediting more time for userland, while under Xen, the kernel is not SMP capable.
66:
67: Notice that, in a MP context, Xen stays behind by a 40% margin for parallel build. Given that Xen overhead is considered negligible, it shows that NetBSD build system gets an important boost when parallelized, at least for bi-CPU setups. Just to show that the concurrent build is not purely rhetorical :)
68:
69: ## Xen ballooning ##
70:
71: [[build-balloon.png]]
72: [[hackbench-balloon.png]]
73: [[sysbench-balloon.png]]
74:
75:
76: In essence, there is not much to say. Results are all below the 5% margin, adding the balloon thread did not affect performance or process creation/scheduling drastically. It is all noise. The timeout delay added by cherry@ seems to be reasonable (can be revisited later, but does not seem to be critical).
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