CPU Optimizations

1,143 · April 22, 2013

Why do you get different results in your Sun system? Which one is flawed?

I honestly have no idea why the result is different, but the output from my Intel system seems to fit much better with the other results posted here so I assume the SPARC result is the wrong one. You could probably check the results against the verified value of Pi (I'm sure that's somewhere online) to see which is actually right. The evidence is definitely against the SPARC box though: it calculated Pi to more than 5000 decimals and isn't consistent with our Intel results (which calculated Pi to exactly 5000 decimals like it was supposed to).

It wouldn't be unprecedented for the FPU to introduce some small percent error in an effort to speed up floating point calculations, which seems ludicrous based on the performance but is a possibility nonetheless. That seems like the most likely reason for the discrepancy. See the well-known Intel Pentium FDIV bug for a real world example of such a flaw.

Yeah why does the SPARC get a different result and also take over 5mins to do it.

I have two theories on why it takes so long. The first is that it is doing floating point emulation in software rather than using the hardware FPU. The second is that Linux 3.2 is not well optimized for the FPU in that machine. The system response time is better than most of the Intel system response times posted thus far, which acceptably fits either theory because the kernel tries to avoid doing floating point calculations as much as possible. (Doing floating point operations in the kernel is difficult and expensive.) The latter theory seems more likely because the performance of that machine is much too good in general for it to be using floating point emulation all the time.

In case it helps, here is the head of /proc/cpuinfo on that system:


cpu		: UltraSparc T1 (Niagara)
fpu		: UltraSparc T1 integrated FPU
pmu		: niagara
prom		: OBP 4.30.4.d 2011/07/06 14:29
type		: sun4v
ncpus probed	: 32
ncpus active	: 32
D$ parity tl1	: 0
I$ parity tl1	: 0
cpucaps		: flush,stbar,swap,muldiv,v9,blkinit,mul32,div32,v8plus,ASIBlkInit
[/CODE]

10,893 · April 22, 2013

It's most probably different on the SPARC because it's a different architecture, can't really compare architectures, bit like the raspberry pi and an old gateway pc.

8,753 · April 22, 2013

Why do you get different results in your Sun system? Which one is flawed?

Probably because one of them uses the x87 fpu and the other uses a proper implementation of IEEE754. x87 uses registers wider than standard floating-point precision, which can lead to more exact results (most stupid idea Intel ever had), however this is unpredictable and unreproducible on other floating point units, or even on other x87s running the same code compiled differently, or if the fpu itself is configured differently on different runs. Or perhaps if the phase of the moon differs. With x87 you never really know what result you're getting. This makes it incredibly hard (when not outright impossible) to make portable floating-point based simulations, unless you can avoid x87 altogether (which is no trivial task in itself).

Reproducitibility of floating point calculations is a hairy topic, and it's largely because of x87.

8,753 · April 22, 2013

It's most probably different on the SPARC because it's a different architecture, can't really compare architectures, bit like the raspberry pi and an old gateway pc.

Floating-point math is a standard (IEEE754) and in theory all implementations should give the same results. In practice it's really freakin' hard to make arbitrary C/C++ floating point code be coherent across different platforms, compilers, and even sometimes the same compiler on the same machine. The real world isn't a nice place. :pinch:

5,577 · April 22, 2013

Here's a few for you ranking from highest performance to lowest, yet the scores are the opposite for this test, haha.

real 0m36.797s

user 0m36.754s

sys 0m0.006s

RHEL 6.3, 2.6.32-279.el6 kernel

8x Xeon E7 8850

-----------

real 0m32.795s

user 0m26.424s

sys 0m0.002s

RHEL 5.9, 2.6.18-348.el5 kernel

4x Xeon E5 2670

-----------

real 0m19.752s

user 0m19.720s

sys 0m0.004s

Linux Mint 14, 3.7.0-7-generic kernel

1x Core i3-3225

11,030 · April 22, 2013

OK So I am going to write a simple guide to compile the mainstream kernel with CPU Optimizations. I will post downloads for mu i7 64bit kernel for you to install. Thanks for the help guys keep them comming, Maybe we could have a Neowin Score chart to see who can get the fastest

1,143 · April 22, 2013

Probably because one of them uses the x87 fpu and the other uses a proper implementation of IEEE734. x87 uses registers wider than standard floating-point precision, which can lead to more exact results (most stupid idea Intel ever had), however this is unpredictable and unreproducible on other floating point units, or even on other x87s running the same code compiled differently, or if the fpu itself is configured differently on different runs. Or perhaps if the phase of the moon differs. With x87 you never really know what result you're getting. This makes it incredibly hard (when not outright impossible) to make portable floating-point based simulations, unless you can avoid x87 altogether (which is no trivial task in itself).

Reproducitibility of floating point calculations is a hairy topic, and it's largely because of x87.

Thanks for the clarification. I had no idea that floating point was done differently on Intel systems than other architectures. Do AMD processors use x87 too? I don't think anyone has posted a result from an AMD system yet. Unfortunately I don't have one online for testing at the moment.

If I'm understanding you right, the SPARC result is more accurate? Why is it more than 5000 places past the decimal point when the Intel results are exactly the 5000 requested? Too bad Rablet didn't post the number produced by the Raspberry Pi. I might have to try it on my Raspberry Pi later so I can compare its result to the SPARC result.

11,030 · April 22, 2013

Interesting topic guys! All I have is Intel Machines at the minute. Dont think anyones posted an AMD offering, Anyway my guide is posted. Am compiling again now will post back later if my results have improved.

5,577 · April 22, 2013

Interesting topic guys! All I have is Intel Machines at the minute. Dont think anyones posted an AMD offering, Anyway my guide is posted. Am compiling again now will post back later if my results have improved.

Okay, here's an AMD:

real 34.882s

user 34.851s

sys 0.019s

RHEL 6.1, 2.6.32-131.0.13.el6 kernel

2x Opteron 2220

Edit: Update with full output:

[root@dhcp-*-**-***-** Desktop]# time echo "scale=5000; a(1)*4" | bc -l
3.141592653589793238462643383279502884197169399375105820974944592307\

81640628620899862803482534211706798214808651328230664709384460955058\

22317253594081284811174502841027019385211055596446229489549303819644\

28810975665933446128475648233786783165271201909145648566923460348610\

45432664821339360726024914127372458700660631558817488152092096282925\

40917153643678925903600113305305488204665213841469519415116094330572\

70365759591953092186117381932611793105118548074462379962749567351885\

75272489122793818301194912983367336244065664308602139494639522473719\

07021798609437027705392171762931767523846748184676694051320005681271\

45263560827785771342757789609173637178721468440901224953430146549585\

37105079227968925892354201995611212902196086403441815981362977477130\

99605187072113499999983729780499510597317328160963185950244594553469\

08302642522308253344685035261931188171010003137838752886587533208381\

42061717766914730359825349042875546873115956286388235378759375195778\

18577805321712268066130019278766111959092164201989380952572010654858\

63278865936153381827968230301952035301852968995773622599413891249721\

77528347913151557485724245415069595082953311686172785588907509838175\

46374649393192550604009277016711390098488240128583616035637076601047\

10181942955596198946767837449448255379774726847104047534646208046684\

25906949129331367702898915210475216205696602405803815019351125338243\

00355876402474964732639141992726042699227967823547816360093417216412\

19924586315030286182974555706749838505494588586926995690927210797509\

30295532116534498720275596023648066549911988183479775356636980742654\

25278625518184175746728909777727938000816470600161452491921732172147\

72350141441973568548161361157352552133475741849468438523323907394143\

33454776241686251898356948556209921922218427255025425688767179049460\

16534668049886272327917860857843838279679766814541009538837863609506\

80064225125205117392984896084128488626945604241965285022210661186306\

74427862203919494504712371378696095636437191728746776465757396241389\

08658326459958133904780275900994657640789512694683983525957098258226\

20522489407726719478268482601476990902640136394437455305068203496252\

45174939965143142980919065925093722169646151570985838741059788595977\

29754989301617539284681382686838689427741559918559252459539594310499\

72524680845987273644695848653836736222626099124608051243884390451244\

13654976278079771569143599770012961608944169486855584840635342207222\

58284886481584560285060168427394522674676788952521385225499546667278\

23986456596116354886230577456498035593634568174324112515076069479451\

09659609402522887971089314566913686722874894056010150330861792868092\

08747609178249385890097149096759852613655497818931297848216829989487\

22658804857564014270477555132379641451523746234364542858444795265867\

82105114135473573952311342716610213596953623144295248493718711014576\

54035902799344037420073105785390621983874478084784896833214457138687\

51943506430218453191048481005370614680674919278191197939952061419663\

42875444064374512371819217999839101591956181467514269123974894090718\

64942319615679452080951465502252316038819301420937621378559566389377\

87083039069792077346722182562599661501421503068038447734549202605414\

66592520149744285073251866600213243408819071048633173464965145390579\

62685610055081066587969981635747363840525714591028970641401109712062\

80439039759515677157700420337869936007230558763176359421873125147120\

53292819182618612586732157919841484882916447060957527069572209175671\

16722910981690915280173506712748583222871835209353965725121083579151\

36988209144421006751033467110314126711136990865851639831501970165151\

16851714376576183515565088490998985998238734552833163550764791853589\

32261854896321329330898570642046752590709154814165498594616371802709\

81994309924488957571282890592323326097299712084433573265489382391193\

25974636673058360414281388303203824903758985243744170291327656180937\

73444030707469211201913020330380197621101100449293215160842444859637\

66983895228684783123552658213144957685726243344189303968642624341077\

32269780280731891544110104468232527162010526522721116603966655730925\

47110557853763466820653109896526918620564769312570586356620185581007\

29360659876486117910453348850346113657686753249441668039626579787718\

55608455296541266540853061434443185867697514566140680070023787765913\

44017127494704205622305389945613140711270004078547332699390814546646\

45880797270826683063432858785698305235808933065757406795457163775254\

20211495576158140025012622859413021647155097925923099079654737612551\

76567513575178296664547791745011299614890304639947132962107340437518\

95735961458901938971311179042978285647503203198691514028708085990480\

10941214722131794764777262241425485454033215718530614228813758504306\

33217518297986622371721591607716692547487389866549494501146540628433\

66393790039769265672146385306736096571209180763832716641627488880078\

69256029022847210403172118608204190004229661711963779213375751149595\

01566049631862947265473642523081770367515906735023507283540567040386\

74351362222477158915049530984448933309634087807693259939780541934144\

73774418426312986080998886874132604720

real 0m34.882s

user 0m34.851s

sys 0m0.019s

1,143 · April 22, 2013

Okay, I commandeered another system for a minute to get an AMD result.


3.141592653589793238462643383279502884197169399375105820974944592307\
81640628620899862803482534211706798214808651328230664709384460955058\
22317253594081284811174502841027019385211055596446229489549303819644\
28810975665933446128475648233786783165271201909145648566923460348610\
45432664821339360726024914127372458700660631558817488152092096282925\
40917153643678925903600113305305488204665213841469519415116094330572\
70365759591953092186117381932611793105118548074462379962749567351885\
75272489122793818301194912983367336244065664308602139494639522473719\
07021798609437027705392171762931767523846748184676694051320005681271\
45263560827785771342757789609173637178721468440901224953430146549585\
37105079227968925892354201995611212902196086403441815981362977477130\
99605187072113499999983729780499510597317328160963185950244594553469\
08302642522308253344685035261931188171010003137838752886587533208381\
42061717766914730359825349042875546873115956286388235378759375195778\
18577805321712268066130019278766111959092164201989380952572010654858\
63278865936153381827968230301952035301852968995773622599413891249721\
77528347913151557485724245415069595082953311686172785588907509838175\
46374649393192550604009277016711390098488240128583616035637076601047\
10181942955596198946767837449448255379774726847104047534646208046684\
25906949129331367702898915210475216205696602405803815019351125338243\
00355876402474964732639141992726042699227967823547816360093417216412\
19924586315030286182974555706749838505494588586926995690927210797509\
30295532116534498720275596023648066549911988183479775356636980742654\
25278625518184175746728909777727938000816470600161452491921732172147\
72350141441973568548161361157352552133475741849468438523323907394143\
33454776241686251898356948556209921922218427255025425688767179049460\
16534668049886272327917860857843838279679766814541009538837863609506\
80064225125205117392984896084128488626945604241965285022210661186306\
74427862203919494504712371378696095636437191728746776465757396241389\
08658326459958133904780275900994657640789512694683983525957098258226\
20522489407726719478268482601476990902640136394437455305068203496252\
45174939965143142980919065925093722169646151570985838741059788595977\
29754989301617539284681382686838689427741559918559252459539594310499\
72524680845987273644695848653836736222626099124608051243884390451244\
13654976278079771569143599770012961608944169486855584840635342207222\
58284886481584560285060168427394522674676788952521385225499546667278\
23986456596116354886230577456498035593634568174324112515076069479451\
09659609402522887971089314566913686722874894056010150330861792868092\
08747609178249385890097149096759852613655497818931297848216829989487\
22658804857564014270477555132379641451523746234364542858444795265867\
82105114135473573952311342716610213596953623144295248493718711014576\
54035902799344037420073105785390621983874478084784896833214457138687\
51943506430218453191048481005370614680674919278191197939952061419663\
42875444064374512371819217999839101591956181467514269123974894090718\
64942319615679452080951465502252316038819301420937621378559566389377\
87083039069792077346722182562599661501421503068038447734549202605414\
66592520149744285073251866600213243408819071048633173464965145390579\
62685610055081066587969981635747363840525714591028970641401109712062\
80439039759515677157700420337869936007230558763176359421873125147120\
53292819182618612586732157919841484882916447060957527069572209175671\
16722910981690915280173506712748583222871835209353965725121083579151\
36988209144421006751033467110314126711136990865851639831501970165151\
16851714376576183515565088490998985998238734552833163550764791853589\
32261854896321329330898570642046752590709154814165498594616371802709\
81994309924488957571282890592323326097299712084433573265489382391193\
25974636673058360414281388303203824903758985243744170291327656180937\
73444030707469211201913020330380197621101100449293215160842444859637\
66983895228684783123552658213144957685726243344189303968642624341077\
32269780280731891544110104468232527162010526522721116603966655730925\
47110557853763466820653109896526918620564769312570586356620185581007\
29360659876486117910453348850346113657686753249441668039626579787718\
55608455296541266540853061434443185867697514566140680070023787765913\
44017127494704205622305389945613140711270004078547332699390814546646\
45880797270826683063432858785698305235808933065757406795457163775254\
20211495576158140025012622859413021647155097925923099079654737612551\
76567513575178296664547791745011299614890304639947132962107340437518\
95735961458901938971311179042978285647503203198691514028708085990480\
10941214722131794764777262241425485454033215718530614228813758504306\
33217518297986622371721591607716692547487389866549494501146540628433\
66393790039769265672146385306736096571209180763832716641627488880078\
69256029022847210403172118608204190004229661711963779213375751149595\
01566049631862947265473642523081770367515906735023507283540567040386\
74351362222477158915049530984448933309634087807693259939780541934144\
73774418426312986080998886874132604720

real    0m48.062s
user    0m48.022s
sys    0m0.006s
[/CODE]

[b]Hardware[/b]

Quad-Core AMD Opteron Processor 8347 HE clocked at 1900.077 MHz
4 GB of RAM

[b]Kernel[/b]

2.6.18-348.1.1.el5.x86_64 (SMP)

11,030 · April 22, 2013

Yeah the Intel ones and the AMD Results differ. Interesting.

1,143 · April 22, 2013

Yeah the Intel ones and the AMD Results differ. Interesting.

More importantly, they both differ from the SPARC result. Apparently all x86 systems use the inconsistent x87 FPU, which I guess justifies the results somewhat.

5,544 · April 22, 2013

real 0m20.791s

user 0m20.721s

sys 0m0.008s

Ubuntu 12.10

VMware Fusion 2 Cores

11,030 · April 22, 2013

Now this is strange. I have compiled the latest Kernel with the optimizations in my guide and I now get this result on an Intel i7. I could have swore it ended differently on rc7 and previous Kernels.

Edit:It must entirely be down to the Optimizations that are on the Kernel but that shouldnt be right :-s


ubuntu@ubuntui7:~$ time echo "scale=5000; a(1)*4" | bc -l
3.141592653589793238462643383279502884197169399375105820974944592307\
81640628620899862803482534211706798214808651328230664709384460955058\
22317253594081284811174502841027019385211055596446229489549303819644\
28810975665933446128475648233786783165271201909145648566923460348610\
45432664821339360726024914127372458700660631558817488152092096282925\
40917153643678925903600113305305488204665213841469519415116094330572\
70365759591953092186117381932611793105118548074462379962749567351885\
75272489122793818301194912983367336244065664308602139494639522473719\
07021798609437027705392171762931767523846748184676694051320005681271\
45263560827785771342757789609173637178721468440901224953430146549585\
37105079227968925892354201995611212902196086403441815981362977477130\
99605187072113499999983729780499510597317328160963185950244594553469\
08302642522308253344685035261931188171010003137838752886587533208381\
42061717766914730359825349042875546873115956286388235378759375195778\
18577805321712268066130019278766111959092164201989380952572010654858\
63278865936153381827968230301952035301852968995773622599413891249721\
77528347913151557485724245415069595082953311686172785588907509838175\
46374649393192550604009277016711390098488240128583616035637076601047\
10181942955596198946767837449448255379774726847104047534646208046684\
25906949129331367702898915210475216205696602405803815019351125338243\
00355876402474964732639141992726042699227967823547816360093417216412\
19924586315030286182974555706749838505494588586926995690927210797509\
30295532116534498720275596023648066549911988183479775356636980742654\
25278625518184175746728909777727938000816470600161452491921732172147\
72350141441973568548161361157352552133475741849468438523323907394143\
33454776241686251898356948556209921922218427255025425688767179049460\
16534668049886272327917860857843838279679766814541009538837863609506\
80064225125205117392984896084128488626945604241965285022210661186306\
74427862203919494504712371378696095636437191728746776465757396241389\
08658326459958133904780275900994657640789512694683983525957098258226\
20522489407726719478268482601476990902640136394437455305068203496252\
45174939965143142980919065925093722169646151570985838741059788595977\
29754989301617539284681382686838689427741559918559252459539594310499\
72524680845987273644695848653836736222626099124608051243884390451244\
13654976278079771569143599770012961608944169486855584840635342207222\
58284886481584560285060168427394522674676788952521385225499546667278\
23986456596116354886230577456498035593634568174324112515076069479451\
09659609402522887971089314566913686722874894056010150330861792868092\
08747609178249385890097149096759852613655497818931297848216829989487\
22658804857564014270477555132379641451523746234364542858444795265867\
82105114135473573952311342716610213596953623144295248493718711014576\
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real 0m21.263s
user 0m21.256s
sys 0m0.004s
[/CODE]

8,753 · April 22, 2013

Thanks for the clarification. I had no idea that floating point was done differently on Intel systems than other architectures. Do AMD processors use x87 too? I don't think anyone has posted a result from an AMD system yet. Unfortunately I don't have one online for testing at the moment.

If I'm understanding you right, the SPARC result is more accurate? Why is it more than 5000 places past the decimal point when the Intel results are exactly the 5000 requested? Too bad Rablet didn't post the number produced by the Raspberry Pi. I might have to try it on my Raspberry Pi later so I can compare its result to the SPARC result.

Intel and AMD implement IEEE754 in two different instruction sets, x87 and SSE. Both were originally designed by Intel; SSE is consistent and x87 isn't.

There could be other causes behind the inconsistency seen here. Floating-point arithmetic does not respect certain mathematic properties like associativity and distributivity, so building using different compilers, or even the same compiler with different flags, can lead to different re-ordering of instructions and thus different result, even on a strictly comformant ieee754 implementation. It's also possible that the software implementation used on SPARC is buggy, I don't know.

Getting portable and reproducible results with floating-point code is very difficult and it appears this particular program fails quite miserably at it; perhaps it doesn't even try to. Avoiding x87 is a step in the right direction, but not a guarantee in itself of consistent results.

April 22, 2013

This looks like an interesting post, thought I would have a play.

Base hardware is AMD FX-8350 Eight-Core Processor, 32GB DDR3@1866, M/B is MSI 990XA-GD55 (bios 23.2).

This is my server system that runs Windows Server 2012 Standard.

I am a total noob when it comes to Linux, so I just grabbed Xubuntu 12.10 and installed into VMware workstation 9.0.2.

This is what i got:

real 1m13.242s

user 1m13.229s

sys 0m0.028s

Bit of a miserable result I think.

I ran the test a few times and noticed that the CPU usage only peaks at 13% (in Xubuntu).

Would be a much better result if i could persaude it to use all the CPU capacity ;)

Tim

10,893 · April 22, 2013

You'll probably find it doesn't need to use the full CPU capacity, what this tests is your accumulator which is inside the CPU (used for mathematical functions) and doesn't run at the same speed as your CPU.

April 23, 2013

ah I switched on my brain and realized it's because the test is single threaded. 100/8(cpu cores) is approx 13%.

1,143 · April 23, 2013


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73774418426312986080998886874132604720

real	4m49.467s
user	4m32.100s
sys    0m0.040s
[/CODE]

[b]Hardware[/b]

ARMv6-compatible processor rev 5 (v6l) clocked at 600 MHz
421 MB of RAM

[b]Kernel[/b]

2.6.35.14-CAI-test40-HK+ armv6l (PREEMPT)

April 23, 2013

BEHOLD THE POWER!

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real 2m35.370s

user 2m34.142s

sys 0m0.104s

processor : 0

vendor_id : CentaurHauls

cpu family : 6

model : 10

model name : VIA Esther processor 1500MHz

stepping : 9

cpu MHz : 1500.062

cache size : 128 KB

Linux Burst 2.6.38-2-686

Debian

1,317 · April 23, 2013

Too bad Rablet didn't post the number produced by the Raspberry Pi.

Here you go:

3.141592653589793238462643383279502884197169399375105820974944592307\
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42875444064374512371819217999839101591956181467514269123974894090718\
64942319615679452080951465502252316038819301420937621378559566389377\
87083039069792077346722182562599661501421503068038447734549202605414\
66592520149744285073251866600213243408819071048633173464965145390579\
62685610055081066587969981635747363840525714591028970641401109712062\
80439039759515677157700420337869936007230558763176359421873125147120\
53292819182618612586732157919841484882916447060957527069572209175671\
16722910981690915280173506712748583222871835209353965725121083579151\
36988209144421006751033467110314126711136990865851639831501970165151\
16851714376576183515565088490998985998238734552833163550764791853589\
32261854896321329330898570642046752590709154814165498594616371802709\
81994309924488957571282890592323326097299712084433573265489382391193\
25974636673058360414281388303203824903758985243744170291327656180937\
73444030707469211201913020330380197621101100449293215160842444859637\
66983895228684783123552658213144957685726243344189303968642624341077\
32269780280731891544110104468232527162010526522721116603966655730925\
47110557853763466820653109896526918620564769312570586356620185581007\
29360659876486117910453348850346113657686753249441668039626579787718\
55608455296541266540853061434443185867697514566140680070023787765913\
44017127494704205622305389945613140711270004078547332699390814546646\
45880797270826683063432858785698305235808933065757406795457163775254\
20211495576158140025012622859413021647155097925923099079654737612551\
76567513575178296664547791745011299614890304639947132962107340437518\
95735961458901938971311179042978285647503203198691514028708085990480\
10941214722131794764777262241425485454033215718530614228813758504306\
33217518297986622371721591607716692547487389866549494501146540628433\
66393790039769265672146385306736096571209180763832716641627488880078\
69256029022847210403172118608204190004229661711963779213375751149595\
01566049631862947265473642523081770367515906735023507283540567040386\
74351362222477158915049530984448933309634087807693259939780541934144\
73774418426312986080998886874132604720

real	4m4.200s
user	4m3.590s
sys	 0m0.080s

CPU: ARMv6-compatible processor rev 7 (v6l)

Kernel: 3.2.27+

11,030 · April 23, 2013

Running it in a VM wont be a true test but nice to see results anyway.

April 23, 2013

ok this time running on real hardware (not in a VM).

Hardware is AMD FX6100 (6 core), 8GB DDR3@1866.

Fresh install of Xubuntu 12.10.

real 0m23.200s

user 0m23.133s

sys 0m0.020s

1,143 · April 23, 2013

CPU: ARMv6-compatible processor rev 7 (v6l)

Kernel: 3.2.27+

Thanks for the extra information! Are you running the armel Debian image or the armhf Raspbian variant? Your Raspberry Pi results are very similar to the result I posted of Debian running on an old smartphone. If you are running the armel version, then that comparison makes sense, because the processor and clock speed are almost identical between the two devices. If you are running the armhf variant, then it makes less sense, because the Raspberry Pi's hardware floating unit should be much faster than the software floating point emulation used to obtain my result.

1,433 · April 23, 2013

I tried to do this on my Guruplug at home, running Debian 6, but it said bc was an unknown command or something..

Fedora 18 on Acer with Intel Pentium P6200

real 0m35.194s

user 0m35.074s

sys 0m0.010s

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