Does more RAM really help?

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The reason I ask this question is because about 3-4 years ago I was listening
to Scott Mueller (popular computer technician) who was explaning how RAM
works. He said that the L1 cache runs at about same speed as the
microprocessor and Intel claims to have a 9/10 'cache hit ratio'. If a 'cache
miss' occurs then the L2 cache also has a 9/10 'cache hit ratio.' He said
only if a cache miss occurs on both the L1 and L2 cache will the physical RAM
will be accessed (which ofcourse is a slower process). Therefore he reasoned
that if we add more RAM you will only be increasing your performance 1% of
the time. And this is why RAM speeds today are so much slower than CPU
speeds; they simply have no reason to keep up.
I was just wondering how logical is this arguement and is it the truth?

Thank you
 
Fazal said:
The reason I ask this question is because about 3-4 years ago I was listening
to Scott Mueller (popular computer technician) who was explaning how RAM
works. He said that the L1 cache runs at about same speed as the
microprocessor and Intel claims to have a 9/10 'cache hit ratio'. If a 'cache
miss' occurs then the L2 cache also has a 9/10 'cache hit ratio.' He said
only if a cache miss occurs on both the L1 and L2 cache will the physical RAM
will be accessed (which ofcourse is a slower process). Therefore he reasoned
that if we add more RAM you will only be increasing your performance 1% of
the time. And this is why RAM speeds today are so much slower than CPU
speeds; they simply have no reason to keep up.
I was just wondering how logical is this arguement and is it the truth?

Thank you
Click to expand...

What was missed was the fact that with most applications...a lot more RAM is
needed than is avail in L1/L2
so a fair amount of RAM is of course needed.
 
Fazal said:
The reason I ask this question is because about 3-4 years ago I was
listening
to Scott Mueller (popular computer technician) who was explaning how RAM
works. He said that the L1 cache runs at about same speed as the
microprocessor and Intel claims to have a 9/10 'cache hit ratio'. If a
'cache
miss' occurs then the L2 cache also has a 9/10 'cache hit ratio.' He said
only if a cache miss occurs on both the L1 and L2 cache will the physical
RAM
will be accessed (which ofcourse is a slower process). Therefore he
reasoned
that if we add more RAM you will only be increasing your performance 1% of
the time. And this is why RAM speeds today are so much slower than CPU
speeds; they simply have no reason to keep up.
I was just wondering how logical is this arguement and is it the truth?

Thank you
Click to expand...

I suspect that you have mis-understood Scott Mueller. You seem to be
comparing ham-hocks to beans; they are two completely different foods that,
taken together, perform an olfactory feat that neither food can obtain
independently of the other.

*CACHE* memory [L1 and, if a processor has it, L2] serves an entirely
different function than *Random Access Memory* (RAM) serves.

CACHE memory exists to store snippets of "action" code (VERB) that the
processor will soon use, or that will be reused multiple times in a sequence
of calculations.
RAM stores not just snippets of code, but entire programs of code (both NOUN
and VERB).

Think of yourself as a "computer", think of RAM as your office, and think of
CACHE memory a workspace where you use each of the individual tools within
your office. From your writing class you have 100 vocabulary words that you
must discover definitions for. From your math class you have 100 equations
upon which you must perform a Laplace Transform.
You (the processor) decide to do your vocabulary first, so you "pre-fetch" a
dictionary and place it in the CACHE (your desk). With your tool place in
CACHE, you do not need to get up from your desk and retrieve a dictionary
100 times for 100 words -- you use, 100 times, the dictionary that is placed
in your CACHE.
Having completed your vocabulary assignment, you discard the dictionary from
CACHE and replace it with a calculator -- you use, 100 times, the
calculator.

Steve
 
The reason I ask this question is because about 3-4 years ago I was listening
to Scott Mueller (popular computer technician) who was explaning how RAM
works. He said that the L1 cache runs at about same speed as the
microprocessor and Intel claims to have a 9/10 'cache hit ratio'. If a 'cache
miss' occurs then the L2 cache also has a 9/10 'cache hit ratio.' He said
only if a cache miss occurs on both the L1 and L2 cache will the physical RAM
will be accessed (which ofcourse is a slower process). Therefore he reasoned
that if we add more RAM you will only be increasing your performance 1% of
the time. And this is why RAM speeds today are so much slower than CPU
speeds; they simply have no reason to keep up.
I was just wondering how logical is this arguement and is it the truth?

Thank you
Click to expand...

Why bring it up here? What exactly does your post have to do with the
OS and it's interaction with hardware? Oh, we both know the answer:
NOTHING.

Take this elsewhere.
 
NoConsequence, and NoManners either... If you don't know what this post has
to do with the OS and it's interaction with hardware, then by all means: take
it elsewhere.

Yes, more RAM really helps, Fazal. Simply put, more RAM means that the OS
can leave larger programs and more data in the RAM, instead of constantly
saving and loading these from and to your hard drive. Loading and saving to
and from RAM is much faster than loading/saving to or from a hard drive. The
end result will be a much better (and faster) performing computer (without
even getting a faster processor!).

Get it now, NoBrain? I'm sorry, I meant NoConsequence!
 
Og said:
Fazal said:
The reason I ask this question is because about 3-4 years ago I was
listening
to Scott Mueller (popular computer technician) who was explaning how RAM
works. He said that the L1 cache runs at about same speed as the
microprocessor and Intel claims to have a 9/10 'cache hit ratio'. If a
'cache
miss' occurs then the L2 cache also has a 9/10 'cache hit ratio.' He said
only if a cache miss occurs on both the L1 and L2 cache will the physical
RAM
will be accessed (which ofcourse is a slower process). Therefore he
reasoned
that if we add more RAM you will only be increasing your performance 1%
of
the time. And this is why RAM speeds today are so much slower than CPU
speeds; they simply have no reason to keep up.
I was just wondering how logical is this arguement and is it the truth?

Thank you
Click to expand...

I suspect that you have mis-understood Scott Mueller. You seem to be
comparing ham-hocks to beans; they are two completely different foods
that, taken together, perform an olfactory feat that neither food can
obtain independently of the other.

*CACHE* memory [L1 and, if a processor has it, L2] serves an entirely
different function than *Random Access Memory* (RAM) serves.

CACHE memory exists to store snippets of "action" code (VERB) that the
processor will soon use, or that will be reused multiple times in a
sequence of calculations.
RAM stores not just snippets of code, but entire programs of code (both
NOUN and VERB).

Think of yourself as a "computer", think of RAM as your office, and think
of CACHE memory a workspace where you use each of the individual tools
within your office. From your writing class you have 100 vocabulary words
that you must discover definitions for. From your math class you have 100
equations upon which you must perform a Laplace Transform.
You (the processor) decide to do your vocabulary first, so you "pre-fetch"
a dictionary and place it in the CACHE (your desk). With your tool place
in CACHE, you do not need to get up from your desk and retrieve a
dictionary 100 times for 100 words -- you use, 100 times, the dictionary
that is placed in your CACHE.
Having completed your vocabulary assignment, you discard the dictionary
from CACHE and replace it with a calculator -- you use, 100 times, the
calculator.
Click to expand...

That is a bit of a complicated explanation, though not inaccurate.

It would be quite possible to connect RAM memory to the CPU that is capable
of operating at the speed the CPU would expect it to. Such memory (known as
static memory) is relatively complicated, physically large and very, very,
expensive. However, it would not require any additional cache, and would
make for a very fast, but very expensive PC.

In practice, a compromise is made and the type of RAM fitted is dynamic
memory, which is relatively simple, small, cheap and slow. Its only
disadvantage is that this latter memory will only remember data for a few
milliseconds so it has to be constantly refreshed. This is all taken care
of in the memory chips themselves these days and so does not actually pose
any problems.

In order to speed up operations, when a memory access is made, that chunk of
memory is copied into a faster L2 cache. In turn a smaller chunk is copied
into an even faster L1 cache. The processor can now access the L1 cache at
full speed. As other chunks are required they are copied as required. This
provides a substantial speed advantage than if there were no cache, but is
not as fast as the first scheme. The caches are made from expensive static
RAM, but are universally built into the processor itself these days.

The process can be reversed if a memory write takes place, but the actual
write back to the L2 cache and then to the dynamic RAM is delayed until it
has to occur or after a suitable time interval. Motherboards can be
configured to perform the write back to the dynamic RAM immediatley.
 
Og said:
The reason I ask this question is because about 3-4 years ago I was
listening
to Scott Mueller (popular computer technician) who was explaning how RAM
works. He said that the L1 cache runs at about same speed as the
microprocessor and Intel claims to have a 9/10 'cache hit ratio'. If a
'cache
miss' occurs then the L2 cache also has a 9/10 'cache hit ratio.' He said
only if a cache miss occurs on both the L1 and L2 cache will the physical
RAM
will be accessed (which ofcourse is a slower process). Therefore he
reasoned
that if we add more RAM you will only be increasing your performance 1% of
the time. And this is why RAM speeds today are so much slower than CPU
speeds; they simply have no reason to keep up.
I was just wondering how logical is this arguement and is it the truth?

Thank you
Click to expand...


I suspect that you have mis-understood Scott Mueller. You seem to be
comparing ham-hocks to beans; they are two completely different foods that,
taken together, perform an olfactory feat that neither food can obtain
independently of the other.

*CACHE* memory [L1 and, if a processor has it, L2] serves an entirely
different function than *Random Access Memory* (RAM) serves.

CACHE memory exists to store snippets of "action" code (VERB) that the
processor will soon use, or that will be reused multiple times in a sequence
of calculations.
RAM stores not just snippets of code, but entire programs of code (both NOUN
and VERB).

Think of yourself as a "computer", think of RAM as your office, and think of
CACHE memory a workspace where you use each of the individual tools within
your office. From your writing class you have 100 vocabulary words that you
must discover definitions for. From your math class you have 100 equations
upon which you must perform a Laplace Transform.
You (the processor) decide to do your vocabulary first, so you "pre-fetch" a
dictionary and place it in the CACHE (your desk). With your tool place in
CACHE, you do not need to get up from your desk and retrieve a dictionary
100 times for 100 words -- you use, 100 times, the dictionary that is placed
in your CACHE.
Having completed your vocabulary assignment, you discard the dictionary from
CACHE and replace it with a calculator -- you use, 100 times, the
calculator.

Steve
Click to expand...

Uh, that explanation is rather off-base. Cache *is* RAM, and *is* used for
the same purpose as main RAM; the only difference is speed (most importantly,
access time). And, with common PCs, cache is used to store data as well
as code.
 
Fazal said:
The reason I ask this question is because about 3-4 years ago I was listening
to Scott Mueller (popular computer technician) who was explaning how RAM
works. He said that the L1 cache runs at about same speed as the
microprocessor and Intel claims to have a 9/10 'cache hit ratio'. If a 'cache
miss' occurs then the L2 cache also has a 9/10 'cache hit ratio.' He said
only if a cache miss occurs on both the L1 and L2 cache will the physical RAM
will be accessed (which ofcourse is a slower process). Therefore he reasoned
that if we add more RAM you will only be increasing your performance 1% of
the time.
Click to expand...
True.

And this is why RAM speeds today are so much slower than CPU
speeds; they simply have no reason to keep up.
Click to expand...
False. Main memory (as opposed to cache RAM) is slower because:
(1) it is implemented in DRAM instead of SRAM to minimize heat; and
(2) it is off-chip -- many nanoseconds away from the CPU
I was just wondering how logical is this arguement and is it the truth?

Thank you
Click to expand...

Adding RAM increases performance only if it reduces paging. Since the page
is on a HD, with an access time of several milliseconds, adding RAM can
replace those multi-mSec accesses with some multi-nSec accesses. And that
improvement of *a factor of a million* can be very noticeable, even in your
hypothetical case where only 1% of accesses miss in both caches.
 
Uh, that explanation is rather off-base. Cache *is* RAM, and *is* used for
the same purpose as main RAM; the only difference is speed (most importantly,
access time). And, with common PCs, cache is used to store data as well
as code.
Click to expand...

Actually, the CPU doesn't address the main ram (what we can
change/swap), it can only access the CACHE. The memory controller feeds
the cache from the main RAM so that the CPU can use it.

--

Leythos
- Igitur qui desiderat pacem, praeparet bellum.
- Calling an illegal alien an "undocumented worker" is like calling a
drug dealer an "unlicensed pharmacist"
(e-mail address removed) (remove 999 for proper email address)
 
NoConsequence, and NoManners either... If you don't know what this post has
to do with the OS and it's interaction with hardware, then by all means: take
it elsewhere.

Yes, more RAM really helps, Fazal. Simply put, more RAM means that the OS
can leave larger programs and more data in the RAM, instead of constantly
saving and loading these from and to your hard drive. Loading and saving to
and from RAM is much faster than loading/saving to or from a hard drive. The
end result will be a much better (and faster) performing computer (without
even getting a faster processor!).

Get it now, NoBrain? I'm sorry, I meant NoConsequence!
Click to expand...
Did you READ that paragraph I responded to? Did you notice it had
NOTHING to do with interactions with the OS? Now do you realize what
I was getting at?

Probably not. You don't seem that bright.

Oh, and your responses go down HERE, you top posting dipshit.
 
The analogy is corrupt. Seek help elsewhere by checking the purpose and
operation of a cpu L1 and L2 cache.

Dave
 
Fazal said:
The reason I ask this question is because about 3-4 years ago I was
listening
to Scott Mueller (popular computer technician) who was explaning how RAM
works. He said that the L1 cache runs at about same speed as the
microprocessor and Intel claims to have a 9/10 'cache hit ratio'. If a
'cache
miss' occurs then the L2 cache also has a 9/10 'cache hit ratio.' He said
only if a cache miss occurs on both the L1 and L2 cache will the physical
RAM
will be accessed (which ofcourse is a slower process). Therefore he
reasoned
that if we add more RAM you will only be increasing your performance 1% of
the time. And this is why RAM speeds today are so much slower than CPU
speeds; they simply have no reason to keep up.
I was just wondering how logical is this arguement and is it the truth?

Thank you
Click to expand...

It depends on what applications your running or plan to run.
 
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