CPU Cache

[rkr1958]

Following are excerpts of the specs on my CPU:

Processor
Model : Intel(R) Pentium(R) 4 CPU 2.60GHz
Speed : 2.59GHzltiplier : 0/1x / 13/1x
Name : P4N (Northwood) Pentium 4 1.6-3.4GHz 1.5-1.6V
Processor Cache(s)
Internal Data Cache : 8kB Synchronous Write-Thru (4-way sectored, 64 byte line size)
Internal Trace Cache : 12kB Synchronous Write-Thru (8-way, 64 byte line size)
L2 On-board Cache : 512kB ECC Synchronous ATC (8-way sectored, 64 byte line size)
L2 Cache Multiplier : 1/1x (2594MHz)

My question ... What's the difference between Internal Data Cache and Internal Trace Cache? I'm familar with the terms L1, L2 (and even L3) Cache. Which one of those (Internal Data or Trace) is my L1? What is the other?

[studtrooper]

I'm pretty sure the internal Data and Trace cache are combined in L1 cache.

[bugster]

Not sure but I would suspect that the 'trace cache' is used for instructions and the data cache is used for data.

[rkr1958]

I'm pretty sure the internal Data and Trace cache are combined in L1 cache.

So that means mean total L1 Cache is 20kB?

Not sure but I would suspect that the 'trace cache' is used for instructions and the data cache is used for data.

That makes a lot of sense. I missed the obvious there.

Thanks a lot guys.

[studtrooper]

Is it that hard to believe? Take this scan of my very crappy P4 1.8GHZ machine I'm on right now and look at the cache part:

[rkr1958]

Is it that hard to believe? Take this scan of my very crappy P4 1.8GHZ machine I'm on right now and look at the cache part:

Interesting, same CPU name (P4, Northwood), L1 & L2 Cache sizes. Differences, Speed 2.6-GHz vs 1.8-GHz and FSB 800-MHz vs 400-MHz. I'm been very happy with the performance of my CPU.

When you say, "my very crappy P4 1.8GHZ" what are you unhappy with? The machine itself or the CPU. To me, on paper your 1.8-GHz, 400-MHz FSB P4 CPU is still a very respectable CPU. Are you having performance and / or stability problems?

[studtrooper]

My P4 1.8ghz dell is a piece of trash. My first Athlon XP 1600+ system from so long ago puts this thing to shame. But then again, I cannot apreciate speed as much as those growing up on sub 100mhz machines, so maybe I'm spoiled?

[rkr1958]

I cannot apreciate speed as much as those growing up on sub 100mhz machines, so maybe I'm spoiled?

My first PC was a Kaypro I running CP/M O/S. I believe it came with 64KB of RAM. It had no harddrive, a pair of 5 1/4 inch floppies and the CPU speed was measure in 1's of MHz.

[fmctm1sw]

Wow. Yeah guys, easy on the 1.8 GHZ machines. Hell, you're looking at a guy that still owns a TRS-80 and a Commodore VIC-20...

[rkr1958]

Wow. Yeah guys, easy on the 1.8 GHZ machines. Hell, you're looking at a guy that still owns a TRS-80 and a Commodore VIC-20...

Oh, the TRS-80. Never owned one but I did use one at work in the early 1980's. We affectionly called them "Trash-80`s" and programed them using BASIC. The old BASIC where variable names were limited in length to 2-characters with the first a letter.

In fact, the first "PC" I worked on when I began work in 1981 was called a Franklin. In fact, I think it must have been invented by Ben Franklin. It had 4K of RAM, no harddrive and a single floppy. Again, the programs were written in basic.

Oh yeah, remember those postage stamp green computer screens.

And while I'm taking a walk down memory lane. I actually used card-decks for my computer programs when I worked with Main Frame Computers (CDC-7600) in my early days. You give your card deck to an operator who would load and give it back. 30 to 45-minutes later you'd get a printout from your computer run. I hated those syntac errors. However, we could at least write our programs in FORTRAN.

[Zisguy1]

Old C64 guy here myself. Similar Basic as with the Trash-80 (I think it was a variation on the original Microsoft Basic written by Gates himself). I used to program hybrid Basic/ASM stuff, very fun.