Bigger caches ? Where ?

Posted Feb 12, 2008 22:04 UTC (Tue) by zlynx (guest, #2285)
In reply to: Bigger caches ? Where ? by khim
Parent article: vmsplice(): the making of a local root exploit

I think you're missing the point here.

L1 cache is, as I understand it, about as fast as chip registers.  So that 16 KB cache has
grown faster and faster over the years.

What is L2 and L3 cache now is *huge* and is likely as fast if not faster than that 1993
Pentium's 16 KB cache.

And all chip cache is hugely faster than system RAM.  Look at benchmarks that show the
optimization of certain algorithms.  When they use cache-optimized blocks instead of streaming
over the entire data set, performance improves a hundred fold in some cases.

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Bigger caches ? Where ?

Posted Feb 12, 2008 22:51 UTC (Tue) by man_ls (guest, #15091) [Link] (3 responses)

Moore's law is still valid: transistors on a chip are doubling every 18 months. However clock speeds are not getting any faster; my old PIV was running at 3.2 GHz, and you seldom see those speeds nowadays. So guess where many (if not most) of all those extra transistors are going. Yep, into the caches.

Bigger caches ? Where ?

Posted Feb 13, 2008 20:23 UTC (Wed) by hmh (subscriber, #3838) [Link] (2 responses)

In mainstream consumer CPUs, maybe the clocks have stabilized (which IS a good thing, we
already waste too much power just to do office work).

Look at the IBM Power6 for some high-clock cores...

Bigger caches ? Where ?

Posted Feb 21, 2008 9:53 UTC (Thu) by renox (guest, #23785) [Link] (1 responses)

>Look at the IBM Power6 for some high-clock cores...

Except that apparently they had a lot of difficulty ramping up the clock..
Plus their CPU does *in order* integer processing which induce a loss of efficiency..

It'd be interesting to have a study which analyse whether going in order for integer
processing to increase the clock really did improve performance or if it was just a marketing
gimmick a la P4.

Power 6 clock high-score and real performance

Posted Feb 23, 2008 17:14 UTC (Sat) by anton (subscriber, #25547) [Link]

It'd be interesting to have a study which analyse whether going in order for integer processing to increase the clock really did improve performance

Take a look at SPEC CPU 2006 results. Last I looked, a 4.7GHz Power6 had similar speed to a 3GHz Core 2 Duo 6850 in both SPECint2006 and SPECfp2006 results.