L1 cache speed query

[CurlyWhirly]

I have a Q9650 and after reading this it got me wondering what speed the L1 cache runs at as it isn't mentioned?

The Q9650 has 4x32 KB of L1 instruction cache and 4X32 KB of L1 data cache and I'm wondering if it simply runs at the same speed as the 12 MB (2x6 MB) of L2 cache i.e. 3 Ghz ?

Just curious.

 

[OrphanBoy]

AFAIK L1 caches have always run at full-speed (they certainly do in modern CPUs). L2 and L3 caches often run slower than the core, although in modern Phenom/Core2/i7 CPUs they run at full-speed.

L1 instruction caches normally supply data faster than the instruction issue can consume, yet do this at a lower rate. So although L1 i-cache in typical CPUs look like they run at 1:1 speed with the core it's not necessarily like this. For example, some supply four instructions worth of data at a time, yet do this every fourth cycle.

 

[CurlyWhirly]

AFAIK L1 caches have always run at full-speed (they certainly do in modern CPUs). L2 and L3 caches often run slower than the core, although in modern Phenom/Core2/i7 CPUs they run at full-speed.

Thanks for answering my query

 

[D D Danneh]

All I know is L1 is faster than L2, which is faster than L3.

Run memtest, you'll find out what MB/s each cache is running at (I think my i7 was something like 120,000 MB/s, 75,000 MB/s, and 30,000 MB/s, but I can't remember).

 

[OrphanBoy]

Yeah that'd be the bandwidth provided by the different cache levels. Tbh that's not too important - it's the latency that really counts! Getting more data than you asked for ages after you asked for it isn't normally helpful

But still wow at 120GB/s!