Author: Christophe Theron
Date: 07:42:04 03/28/01
Go up one level in this thread
On March 28, 2001 at 09:44:30, Robert Hyatt wrote:
>On March 27, 2001 at 22:43:28, Christophe Theron wrote:
>
>>On March 27, 2001 at 22:03:31, Robert Hyatt wrote:
>>
>>>On March 27, 2001 at 18:12:42, Christophe Theron wrote:
>>>
>>>>On March 27, 2001 at 14:08:03, Robert Hyatt wrote:
>>>>
>>>>>On March 27, 2001 at 12:55:10, Christophe Theron wrote:
>>>>>
>>>>>>
>>>>>>
>>>>>>That's right.
>>>>>>
>>>>>>Actually as the title says, the message is directed to people who are
>>>>>>considering to buy a dual.
>>>>>>
>>>>>>As far as I know quads are so expensive that it would be ridiculous to buy one
>>>>>>just to play chess.
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>At the moment, perhaps. 6 years ago duals were just as expensive. Now they
>>>>>are dirt cheap. As quads become more common, their prices will continue to
>>>>>drop. 5 years ago a quad MB for pentium pro 200s would set you back almost
>>>>>$8,000. Today you can buy an Intel SC450NX for 2500 bucks, that includes
>>>>>three hot-swappable 400 wat power supplies, motherboard, 6-slot hot-swap raid
>>>>>disk cage, 3 on-board scsi controllers, 1 on-board video controller, etc.
>>>>>
>>>>>All you lack is cpus, memory and drives.
>>>>>
>>>>>That is a huge reduction. The curve is going downward each year. Now the
>>>>>quads are slowly reaching reasonable price points while the 8-way boxes are
>>>>>way expensive. In 5 years that too will change I'll bet...
>>>>
>>>>
>>>>
>>>>So I would advice people who are considering buying a dual right now to delay
>>>>their buy by several years...
>>>
>>>Using that logic you should advise everyone to _never_ buy a computer, because
>>>next year will _always_ have a faster processor.
>>
>>
>>
>>No, it's not the same logic.
>>
>>You are saying that "the curve is going downward each year", which means that
>>the price difference between a single processor machine and a dual is smaller
>>every year.
>>
>>Based on this remark, it is clear that what you get for your money on a dual
>>will at some point be better than what you get for a single.
>>
>>This is not dependant to the typical speed at that moment in time. It's not the
>>same as saying "wait for next year, you'll get a faster computer".
>>
>>It's like saying "a dual right now is not worth it when you compare to what you
>>get with a single, but wait because soon it will be".
>>
>>
>>
>
>Ask a mathematician "Can you write a function that starts at some fairly
>high value (Y=f(x)) such that the value of the function _always_ gets smaller
>as X increases, but the function _never_ crosses the X axis?"
>
>The price of a dual _may_ never get cheaper than a single. But it will
>one day get _very_ close, because I would expect that within 5 years we will
>have a single chip with more than one processor. Companies like Ncube have
>already done this. Other companies are talking about "multiple threads of
>execution on a single chip" which is really multiple processors. (Alpha
>21464 comes to mind).
I do not disagree. But basically the idea is: a dual will maybe be a good idea
in several years...
>>>>>>You are always thinking with unlimited resources in mind!
>>>>>>
>>>>>>I don't disagree with you here, but in real life there are people wondering if
>>>>>>it's worth it to buy a dual.
>>>>>>
>>>>>>And depending on how much money they can put on it, they will have to choose
>>>>>>between a single 1.GHz and a dual 1GHz.
>>>>>
>>>>>OK... but there the dual will perform like a 1.7ghz machine. Which will
>>>>>turn into around 60 rating points improvement. That is not trivially
>>>>>ignorable.
>>>>>
>>>>>Each time I teach a parallel programming course here, I will find around one
>>>>>out of every 10 students has a dual-processor machine already. And when I ask
>>>>>what they paid, they generally say 500-1000 US bucks...
>>>>
>>>>
>>>>
>>>>In the place I live, I cannot even buy a dual. I must order it overseas.
>>>>
>>>>Bob, there are people outside the United State of America, you know.
>>>
>>>
>>>I ordered mine. There is no "local store" that sells quads here. You can
>>>go to any local computer store and find a dual however... Gateway even sells
>>>them at the local outlet..
>>
>>
>>
>>What you can get where you live has nothing to do with what I can where I live.
>>
>
>
>I have no idea what kind of import tax you have to live with. But you can
>certainly order via email. If your country puts up walls to make technology
>unavailable, that is a problem. But it isn't a problem _everywhere_.
When I buy by email, I pay taxes which are made up so the end price is less
interesting than buying in stores.
I have bought my PalmIIIx two years ago from Outpost. I have been forced to
because I could not even find it in the stores here. But I have paid some 20% of
taxes.
Yes my country puts up walls with these taxes.
Now, what do you suggest?
FYI it's the same in many countries.
>>>>You are very lucky to live in a place where you can get all kind of high tech
>>>>stuffs for a fraction of your monthly salary, but in other countries a dual
>>>>represents a huge amount of money.
>>>
>>>A dual represents 500 bucks for 2x800 or so. I don't know what the exchange
>>>rate is, but that can't be huge...
>>
>>
>>
>>Where I live you need much more money to buy a dual.
>>
>>
>>
>>
>>
>>>>For example, a dual represents more than my average monthly salary.
>>>
>>>
>>>You _really_ make less than $500 US dollars per month?
>>
>>
>>
>>No, it's just that a dual here costs much more than $500.
>>
>>Sometimes I wonder if you have ever travelled outside USA...
>>
>>
>>
>
>
>I have been all over the world. I have bought high-tech devices in Europe
>as they were actually cheaper than in the US, for example.
Have you been in the caribbean?
Have you been in Africa?
Have you been in India?
Have you been in South America?
Open your eyes, Bob.
>>>>>>If you can afford to buy a dual 1.2GHz, then you just stop after reading the
>>>>>>first paragraph.
>>>>>>
>>>>>>If not, then I think the rest is worth reading...
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>That is flawed. For multiple reasons. The shared hash table holds _most_ EGTB
>>>>>>>results after a single probe. The EGTB cache is threaded and shares data read
>>>>>>>between the two (or more threads). With the compression scheme Eugene uses,
>>>>>>>the reads are kept to a minimum. I have run extensive tests on my quad with
>>>>>>>one single 9-gig SCSI drive servicing 4 threads for EGTB reads. I don't see
>>>>>>>any severe strangulation due to disk backlogs. most threads are searching
>>>>>>>close enough to each other in the tree that they are probing the _same_
>>>>>>>tablebases. The caching Eugene wrote handles this quite well.
>>>>>>
>>>>>>
>>>>>>
>>>>>>OK, I admit that I have not done any test on this issue, so your input is
>>>>>>appreciated.
>>>>>>
>>>>>>If my figures are wrong I will publish an update for this text.
>>>>>>
>>>>>>Do you have any measure of the slowdown expected when 2 thread are accesing
>>>>>>intensively the same EGTB files? That would help us to compute the corresponding
>>>>>>ELO loss.
>>>>>
>>>>>I generally don't notice any degradation at all. Mainly because of the large
>>>>>well-managed cache buffers, no doubt. But then the operating system also does
>>>>>a lot of file caching on top of what Eugene does, and all of this (on a 512mb
>>>>>machine) goes a long way toward controlling "disk buzz".
>>>>
>>>>
>>>>
>>>>Well on my computer when I set up an endgame position I have my hard disk
>>>>working really hard.
>>>>
>>>>I can hardly see how this poor hard disk could manage to serve two threads
>>>>instead of one without some performance penalty.
>>>
>>>
>>>First, the two threads are searching positions that are similar, so they will
>>>both probe the same tables for the most part. And since the probe code uses
>>>a shared cache for both threads, many reads are eliminated. And once a
>>>position is probed, it sticks in the hash table from that point forward
>>>anyway...
>>>
>>>I typically see very little slowdown when reaching 8-10 pieces on the board.
>>>In a few rare cases, it does slow way down but it isn't very common with the
>>>way I implemented the probe...
>>>
>>>
>>>
>>>
>>>>
>>>>On the other hand, if you need to have a high perf SCSI drive to satisfy the
>>>>needs of the dual, and such an amount of memory, this has to be added to the
>>>>invoice.
>>>
>>>SCSI and EIDE are not too far apart. Typically a couple of hundred bucks
>>>added for the same size. And EIDE is not horrible for database probes. I
>>>run on such machines all the time and don't see any serious performance
>>>problem when compared to SCSI.
>>
>>
>>
>>And what is a couple of hundred bucks... Nothing. Can't even get a meal for
>>that... :)
>>
>>
>
>
>I have been to restaurants where that would not get you in the front door.
>
>:)
I have lived in places where you can feed a family for one month with this
couple bucks.
OK, this family does not care much about a single or dual processor computer...
However in some countries this amount of money really makes a difference.
>>>>Remember that all this is about what you get for the money, what you need really
>>>>and is it worth it.
>>>
>>>Almost all new PCs have 256mb of RAM. 128mb DIMMS are selling for 50 bucks
>>>nowadays, so going to 512mb adds $100 to the price of the machine. And the
>>>machines I use are pretty much all 512mb boxes... This seems to work
>>>acceptably.
>>
>>
>>
>>Again: the prices in the US have nothing to do with the prices OUTSIDE.
>>
>>
>
>
>What do you pay for a 128mb DIMM?
>
>current price here is 50 bucks US.
Current price HERE for 128Mb SDRAM 133 is FF 690, that is approximately $94.
I can get it for a little less but in this case the product has to be ordered
overseas (in France actually) and will take several days to be available. And
for this I must pay in advance. And if the hardware has a problem it must be
returned to France for repairing or exchange.
So I am almost forced to pay a little bit more and buy from a company that as
the products available in quantity here.
Christophe
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