|
D / Paul - Thanks for pointing out CoreTemp,
that is a nice little tool. Finished testing now, CoreTemp says the max temp for
my CPU should be 100 degrees C. Idle temps are about 42, and under full
load it takes about 10 mins for the temps to creep up to 68, then stops right
there and never gets any higher. So on this setup anyway, it seems that I have
quite a nice margin of safety...
D - re overclocking, I took another look at the
BIOS just for the heck of it....Should I be seeing some sort of setting for
"multiplier"?....because I can't find one so am thinking that you are *still*
correct and Dell is not letting us do this....Well that should make my secision
*really* easy... 8 - )
Steve
----- Original Message -----
Sent: Tuesday, May 27, 2008 1:17 PM
Subject: RE: [amibroker] Re: Dual-core
vs. quad-core
As I recall Dell has used proprietary motherboards in the
past and have prevented any overclocking. I think I've read that they
are starting to use more mainstream components but I don't know how wide
spread that is. Dell has taken the attitude (again, in the
past) that they don't want you messing with it and cause support
problems.
d
PS - when you download coretemp - use the main link and
not one of the mirror sites - they look like traps to me - very confusing - I
tried one and somehow wound up on a page that wanted me to pay for some other
software.
Hi D - Thank you! I have looked over
the CoreTemp website now, I will install it and run some tests before I go
any further. I definitely want to know that I am not causing temps to rise
to a level that might damage the CPU. I think I will pass on the
overclocking for now, but FYI I am just using the stock fan that came with
the computer...may have to think about changing it if CoreTemp shows overly
high temps. Yes my CPU is the Intel Q6600, I don't really know any details
about the motherboard, I built the computer online at Dell if that
tells you anything... Thanks again, I can report back with CoreTemp
results if anyone is interested...
Steve
----- Original Message -----
Sent: Tuesday, May 27, 2008 11:21
AM
Subject: RE: [amibroker] Re:
Dual-core vs. quad-core
As long as the temp stays down you'll be ok.
Several years ago I had a water cooled dual Xenon rig and had some runs
that took several days - never missed a beat.
Are you using the cpu fan that came with the chip or
an after market one? If you do overclock then you'll definitely need
to get a good after market fan - check www.maximumcpu.com for reviews.
I'd do it anyway just as insurance - the prices are very reasonable
unless you get exotic which shouldn't be necessary.
I looked back in the thread but didn't see where you
said what mother board you're using... And you did mention the 6600 - is
that your cpu?
d
Hi Paul - Something occurred to me today
and I was hoping to get your opinion ( as well as D's or anyone
else with the knowledge who would care to comment ). Do you think, even
*without* overclocking, that running these chips flat-out at 100% for
hours or days at a time could possibly cause overheating and subsequent
damage/destruction to the chip? Is there a simple and cheap way to
just monitor the temps ( no overclocking involved ) to be sure we
do continue running flat-out if temps are approaching or entering the
danger zone? Thanks very much!
Steve
----- Original Message -----
Sent: Monday, May 26, 2008 7:44
AM
Subject: RE: [amibroker] Re:
Dual-core vs. quad-core
Steve,
My knowledge on OC is quite limited, I have
only OCed 3 pcs in the last 4 to 5 years. Fortunately, they are all
still working, so you can say that my experiences have been
favourable. OC reminds a lot about Car Hot Rodding in my younger days.
they are quite similar, both are attempts to modify a basically mass
manufactured product to performance higher than their
specifications. Both are based on home grown wisdom rather than
instituitionalised research. OCing is basically elevating both the CPU
clock speed as well as that of the memory bus, and my methods, all
from what I read on the internet are always based on first clocking
the memory controller hub (MCH), and once that is done,
overclock the CPU by increasing the multiplier, (CPU speed is always
adjusted as a multiplier of bus speed becasue they need to be
synchronised).
The danger related to OC is always that of
overheating, firstly the CPU, and secondary the MCH. So choosing a MB
that has decent cooling features for particularly the MCH is of the
most importance.(CPU are always well looked after by MB manufacturers,
and increasingly MCH is going the same way). In addition, the faster
the memory, the more sucessful the exercise is. So My advice is always
getting the fastest memory you can afford. (this is even more so given
what Tomasz has said recently in his AB performance
tests.
Before you overclock, you need to download a
few tools
1. cpuz
2. coretemp
3. memory tesing
You also need to find a set of instructions
for your MB. I found this set of instruction for my MB pretty good http://www.hardforum.com/showthread.php?t=1169366 In
this instruction, you will find where to download the tools I
mentioned, as well as a good methodology to follow. You may be able to
find you MB specific instructions on this site.
Also I found that disabling all devices that
I dont need helps - these include parallel and serial ports,
basically all the things I dont use and I can disable
through the Bios setting.
Testing: I only use AB for stress and
performance testing (I use the recommened software from the
site for diagnostic tests), because that is what I'm ocing for.
What I would suggest would be to use a few of your AFLs, insert
in them a few Getperformancecounter statements (AB
function). These should include a relatively
simple AFL, a long and complicated AFL testing lots of
symbols (to test Memory access performance) and one
that is somewhere in between. At the same time - monitor the
temperatures. These are far more meaningful tests than the stress
tests that most OC sites recommend.
I think
dingo is quite an expert in this area. may be he will say a few
words.
Cheers
Paul.
Hi Paul - I found your comment about
overclocking interesting, have googled around a bit but find that
most of the discussion is over my head. For example The Overclockers
Forum
discusses overclocking the Intel Q6600
chip on my new computer and people are claiming to get as much as
3.8GH out of this 2.4 GH chip. If you can find the time, would you
mind saying a few words about overclocking, how it is done, and what
are the dangers/limits etc? Do you need special software to monitor
the core temps? Thanks!
Steve
----- Original Message -----
Sent: Wednesday, May 14, 2008
2:12 AM
Subject: RE: [amibroker] Re:
Dual-core vs. quad-core
I havent noticed any slow down
when I run 2 instances of AB optimizing almost on a
continuous bases on my core 2 Duo. I have 4 Mb L2 cache.
In fact with overclocking, I'm able to increase the core speed
significantly, and noticably faster on AB optimization,
without increasing the temps to above 50 deg
C
Hello,
I just run the same code on my relatively new
notebook (Core 2 Duo 2GHz (T7250))
and the loop takes less
than 2ns per iteration (3x speedup). So it looks like the data
sits entirely inside the cache.
This core 2 has 2MB of cache
and thats 4 times more than on Athlon x2 I got.
> If
what you say is true, and one core alone fills the memory
> bandwidth, then there should be a net loss of
performance while
> running two copies of ami.
It
depends on complexity of the formula and the amount of data per
symbol
you are using. As each array element has 4 bytes, to
fill 4 MB of cache
you would need 1 million array elements or
100 arrays each having 10000 elements
or 10 arrays each
having 100K elements. Generally speaking people testing
on
EOD data where 10 years is just 2600 bars should see speed
up.
People using very very long intraday data sets may see
degradation, but
rather unnoticeable.
Best
regards,
Tomasz Janeczko
amibroker.com
----- Original
Message -----
From: "dloyer123" <dloyer123@xxxxxxcom>
To:
<amibroker@xxxxxxxxxps.com>
Sent:
Tuesday, May 13, 2008 8:12 PM
Subject: [amibroker] Re:
Dual-core vs. quad-core
> Nice, tight loop. It is good
to see someone that has made the effort
> to make the
most out of every cycle and the result shows.
>
>
My new E8400 (45nm 3GHz, dual core) system should arrive
tomorrow.
> The first thing I will do will be to
benchmark it running ami. I run
> portfolio backtests
over a few years of 5 minute data over a thousand
> or so
symbols. Plenty of data to overflow the cache, but still fit
> in memory. No trig.
>
> I'll post what I
find.
>
> If what you say is true, and one core
alone fills the memory
> bandwidth, then there should be
a net loss of performance while
> running two copies of
ami.
>
>
>
> --- In amibroker@xxxxxxxxxps.com,
"Tomasz Janeczko" <groups@xxx>
>
wrote:
>>
>> Hello,
>>
>>
FYI: SINGLE processor core running an AFL formula is able to
> saturate memory bandwidth
>> in majority of
most common operations/functions
>> if total array
sizes used in given formula exceedes DATA cache
size.
>>
>> You need to understand that AFL
runs with native assembly speed
>> when using array
operations.
>> A simple array multiplication like
this
>>
>> X = Close * H; // array
multiplication
>>
>> gets compiled to just 8
assembly instructions:
>>
>> loop: 8B 54 24
58 mov edx,dword ptr [esp+58h]
>> 00465068 46 inc
> esi ; increase counters
>> 00465069 83 C0 04
add eax,4
>> 0046506C 3B F7 cmp esi,edi
>>
0046506E D9 44 B2 FC fld dword ptr [edx+esi*4-
> 4] ; get
element of close array
>> 00465072 D8 4C 08 FC fmul
dword ptr [eax+ecx-
> 4] ; multiply by element of high
array
>> 00465076 D9 58 FC fstp dword ptr [eax-
>
4] ; store result
>> 00465079 7C E9 jl
> loop ;
continue until all elements are processed
>>
>> As you can see there are three 4 byte memory
accesses per loop
> iteration (2 reads each 4 bytes long
and 1 write 4 byte long)
>>
>> On my (2 year
old) 2GHz Athlon x2 64 single iteration of this loop
>
takes 6 nanoseconds (see benchmark code below).
>> So,
during 6 nanoseconds we have 8 byte reads and 4 byte store.
> Thats (8/(6e-9)) bytes per second = 1333 MB per second
read
>> and 667 MB per second write simultaneously i.e.
2GB/sec combined !
>>
>> Now if you look at
memory benchmarks:
>> http://community.compuserve.com/n/docs/docDownload.aspx?webtag=ws-
>
pchardware&guid=6827f836-8c33-4063-aaf5-c93605dd1dc6
>>
you will see that 2GB/s is THE LIMIT of system memory speed on
> Athlon x64 (DDR2 dual channel)
>> And that's
considering the fact that Athlon has superior-to-intel
> on-die integrated memory controller
(hypertransfer)
>>
>> // benchmark code - for
accurrate results run it on LARGE arrays -
> intraday
database, 1-minute interval, 50K bars or more)
>>
GetPerformanceCounter(1);
>> for(k = 0; k <
1000; k++ ) X = C * H;
>> "Time per single iteration
[s]="+1e-3*GetPerformanceCounter()/
>
(1000*BarCount);
>>
>> Only really
complex operations that use *lots* of FPU (floating
>
point) cycles
>> such as trigonometric (sin/cos/tan)
functions are slow enough for
> the memory
>> to
keep up.
>>
>> Of course one may say that I
am using "old" processor, and new
> computers have faster
RAM and that's true
>> but processor speeds increase
FASTER than bus speeds and the gap
> between processor
and RAM
>> becomes larger and larger so with newer CPUs
the situation will be
> worse, not better.
>>
>>
>> Best regards,
>> Tomasz
Janeczko
>> amibroker.com
>> ----- Original
Message -----
>> From: "dloyer123"
<dloyer123@x..>
>> To: <amibroker@xxxxxxxxxps.com>
>>
Sent: Tuesday, May 13, 2008 5:02 PM
>> Subject:
[amibroker] Re: Dual-core vs. quad-core
>>
>>
>> > All of the cores have to share the same front
bus and
> northbridge.
>> > The northbridge
connects the cpu to memory and has limited
>
bandwidth.
>> >
>> > If several cores
are running memory hungry applications, the
> front
>> > buss will saturate.
>> >
>> > The L2 cache helps for most applications, but
not if you are
> burning
>> > through a few
G of quote data. The L2 cache is just 4-8MB.
>> >
>> > The newer multi core systems have much faster
front buses and
> that
>> > trend is likely
to continue.
>> >
>> > So, it would be
nice if AMI could support running multi cores,
> even
>> > if it was just running different optimization
passes on different
>> > cores. That would saturate
the front bus, but take advantage of
> all
>>
> of the memory bandwidth you have. It would really help
those
> multi
>> > day walkforward
runs.
>> >
>> >
>> >
>> > --- In amibroker@xxxxxxxxxps.com,
"markhoff" <markhoff@> wrote:
>>
>>
>> >>
>> >> If you have
a runtime penalty when running 2 independent AB jobs
> on
>> > a
>> >> Core Duo CPU it might
be caused by too less memory (swapping to
>> >
disk)
>> >> or other tasks which are also running
(e.g. a web browser, audio
>> >> streamer or
whatever). You can check this with a process
explorer
>> >> which shows each tasks CPU
utilisation. Similar, 4 AB jobs on a
> Core
>>
>> Quad should have nearly no penalty in
runtime.
>> >>
>> >> Tomasz
stated that multi-thread optimization does not scale good
>> > with
>> >> the CPU number, but
it is not clear to me why this is the case.
> In
>> > my
>> >> understanding, AA
optimization is a sequential process of
> running
>> > the
>> >> same AFL script with
different parameters. If I have an AFL with
>> >>
significantly long runtime per optimization step (e.g. 1 minute)
> the
>> >> overhead for the
multi-threading should become quite small and
>>
>> independent tasks should scale nearly with the number
of CPUs
> (as
>> > long
>> >>
as there is sufficient memory, n threads might need n-times
more
>> >> memory than a single thread). For sure
the situation is
> different if
>> >> my
single optimization run takes only a few millisecs or
>
seconds,
>> > then
>> >> the
overhead for multi-thread-managment goes up ...
>>
>>
>> >> Maybe Tomasz can give some
detailed comments on that issue?
>> >>
>> >> Best regards,
>> >>
Markus
>> >>
>> >
>> >
>> >
------------------------------------
>>
>
>> > Please note that this group is for
discussion between users only.
>> >
>>
> To get support from AmiBroker please send an e-mail
directly to
>> > SUPPORT {at}
amibroker.com
>> >
>> > For NEW RELEASE
ANNOUNCEMENTS and other news always check DEVLOG:
>>
> http://www.amibroker.com/devlog/
>>
>
>> > For other support material please check
also:
>> > http://www.amibroker.com/support.html
>>
> Yahoo! Groups Links
>> >
>> >
>> >
>>
>
>
>
>
------------------------------------
>
> Please note that this group is for discussion between
users only.
>
> To get support from AmiBroker
please send an e-mail directly to
> SUPPORT {at}
amibroker.com
>
> For NEW RELEASE ANNOUNCEMENTS and
other news always check DEVLOG:
> http://www.amibroker.com/devlog/
>
> For other support material please check also:
>
http://www.amibroker.com/support.html
>
Yahoo! Groups Links
>
>
>
No virus found in this incoming
message.
Checked by AVG.
Version: 8.0.100 / Virus Database:
269.24.1/1468 - Release Date: 5/26/2008 3:23
PM
No virus found in this incoming
message.
Checked by AVG.
Version: 8.0.100 / Virus Database:
269.24.1/1468 - Release Date: 5/26/2008 3:23
PM
__._,_.___
Please note that this group is for discussion between users only.
To get support from AmiBroker please send an e-mail directly to
SUPPORT {at} amibroker.com
For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
http://www.amibroker.com/devlog/
For other support material please check also:
http://www.amibroker.com/support.html
![]()
__,_._,___
|