2009/1/9 Matt Sealey <matt@genesi-usa.com>:
On Fri, Jan 9, 2009 at 4:30 AM, Rob OpenSuSE <rob.opensuse.linux@googlemail.com> wrote:
Years ago memory access on first micro I used, was 1 or 2 CPU cycles. Now we have new chips with L3 caches taking 45 cycles, and system memory a lot more (100+?); so the old "memory is cheap and fast" meme doesn't hold so well now, even though memory is cheap, and faster thand it used to be,
compared to processing speed increase it has lagged.
^^^^^^^^^^^^^ see relative comparision
I'm not sure I agree with you here. Memory is cheap and fast, but CPU cycles have gotten shorter. 11 cycles on a QDR 800MHz bus goes much faster than 2 cycles on a 33Mhz bus, if it was even that. Even 140 cycles to main memory is faster. And once you get over the latency, the data is burst in and cached for longer.
On old systems, bloat was causing a few megabytes of extra memory access, now it can be 100-400MB. And it's no 11 cycles, but CPUs wait 100's on cache misses, never mind if there's a page fault and disk access involved. In relative terms, memory has become slower, so even on systems which never have memory pressure, you don't want your desktop programs to all presume they can use major chunks of physical memory, as if they had system all to themselves. -- To unsubscribe, e-mail: opensuse-factory+unsubscribe@opensuse.org For additional commands, e-mail: opensuse-factory+help@opensuse.org