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Celeron 2GHz Cache Detection?
EAJoe asks: "I have small problem with one Celeron 2GHz machine. Linux kernel 2.4.18-24.7 doesn't seem to switch L2 cache on! This CPU apparently _has_ 128K of L2. There is nothing about L2 in the logs, and /proc/cpuinfo shows an L1D size of 8K instead. Of course I have enabled L2 in BIOS settings (the motherboard is an ASUS P4S533-E, by the way). The CPU overclocks easily up to 3.5 GHz, running stable at 3 - it seems that cache is really switched off. At 3 GHz g++ compilation times are similar to Athlon XP 1800+ machine. I don't have windows on this computer to check this out, but Intel DOS utility shows a Celeron 2000 w/128k L2, also there is '128K' written on the CPU's die. Any suggestions?"
The first link that returns is an old kernel patch, specifically for enabling the L2 cache on a Celeron, although with "powerleap", whatever that is. That is something to try though, just make sure you have a backup kernel to boot from.
Also, there was a post to lkml with a similar question here without a solution.
If you don't find a solution, the best place to post isn't slashdot but to LKML.
"Why should I be content to simply live in this world, when I, as a human being, can CREATE it?" - Oertel
Hmmm, I doubt that without the L2 cache compilation times would be anywhere near the Athlon 1800+. More like an Athlon 180+. Compilation is a very random-memory-access process, so it would kill the P4 core with its relatively large memory latency without a cache.
Try running a test that repeatedly accesses a block of memory 124, 125, 126, 127, 128 etc. KB in size. If you see a significant drop in speed when the block size grows above 128, you probably have your cache.
Anyway, is it the _kernel_'s job to turn on the cache? Isn't that supposed to be the BIOS' job?
Cliff, I have a suggestion. How about, when you get a question from someone, read it, do a quick 10 second google search for the answer, and if you find the answer, don't post it! Great concept huh!?
Then, instead of putting the lame question on SLASHDOT for cryin out loud, just email him the answer that you found in 10 seconds!
-Anonymouse
-
I fear bad karma...so I hide.
How is this offtopic? Buddy overclocked his celeron, burned out the L2 cache, now the L2 doesn't work.
I have a 1.7ghz p4 williamete with 128kb of L2 (celeron 1.7ghz :P) (stable at 2.1ghz+ with intel OEM HSF rated to 2.4ghz)... Some programs do actualy have trouble determining the cache of the CPU, (2 mIRC scripts say 0kb, and a few other programs display blanks under L2..)
Dont know if its related but yea......
Can you please try running your compilation benchmark with the BIOS attempting to turn the cache on and the BIOS attempting to turn the cache on, and verify that the compilation times match? Please try doing the compilation a few times each way, so you can have some sense of the variation not due to this change. That would help confirm whether the cache is indeed off in both cases.
although with "powerleap", whatever that is
:-).
"Powerleap" probably refers to the device sold by the company, that allows you to mount certain proc types on motherboards that wouldn't accept them otherwise, either because of different pinouts or whatever reason (IIRC even one where the voltages were different?), within certain limits (I don't think they sell anything that allows you to plug an 486 into a Socket A slot
the celeron only come swith 128k that will probbaly help u understand why its only 128k. Ddin't u no that when u bought it?
Inspired by this thread, I double-checked one of my systems, found that the L2 cache wasn't being picked up because of a BIOS bug, flashed the BIOS with the newest version and got an instant, free speed boost on an aging machine.
Thanks, slashdot!
I'm having the same problem with a 2ghz 478 pin Celeron. I upgraded the BIOS, have tried various cachesize= hacks and have even tried modifying arch/i386/kernel/bluesmoke.c a bit to force l2size, but that hasn't worked. The code from powerleap doesnt apply to this situation. There is a genuine problem here.
processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 2
model name : Intel(R) Celeron(R) CPU 2.00GHz
stepping : 7
cpu MHz : 2000.123
cache size : 8 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm
bogomips : 3984.58
This system was sold for 99$ at Frys Electronics (2ghz cpu 128k L2) (ECS p4 mainboard p4vxasd2+) and hit alot of customers.
Even with the most recent bios update, the machine still dosen't respond differently when L2 cache is enabled on the bios *or* disabled.
The problem is that 478 pin Celeron's differ from other chips in some way when it comes to enabling the bios. Please, someone point me in a better direction, I have researched everywhere, and cannot solve this problem myself. Will read replies here.
It's not the hardware problem! - in win2k with drivers from the MB's CD, Sandra cache benchmark shows great results for L2 cache, below 128KB block size beating at 3GHz everything except Xeon 2800. So the cache is definitely 128KB, running with full CPU clock. Only linux kernels are not able to switch it on, because I can't believe that the CPU itself can be twice as slow as Athlon XP at the same clock frequency. (compilation times for Cel@3000 similar to AthlonXP@1533).
I made google search, of course, found question you mentioned, but I have different problem. POST on my PC doesn't show L2 cache size, (or it disappears too fast ;] - I'll check), but in Win2K everything is OK in Sandra L2 cache benchmarks. Cache works VERY fast and performance drops above 128KB blocks.
Probably you are right suggesting to directly contact people working on kernel, thx
;) I thought the same, until I installed win2k and Sandra benchmarks which proved that L2 feels good and goes like crazy at 3000...