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Re: Out-Of-Date Optimizations? New Idioms? RAM vs. CPU

by Abigail-II (Bishop)
on Jul 21, 2003 at 08:04 UTC ( #276176=note: print w/ replies, xml ) Need Help??


in reply to Re: Re: Out-Of-Date Optimizations? New Idioms? RAM vs. CPU
in thread Out-Of-Date Optimizations? New Idioms? RAM vs. CPU

If you recalculate something, so that the something doesn't stay in memory, it won't stay in the cache either. The cache is a memory cache - what's there is also in the main memory.

CPU's have become faster, but main memories have become bigger. Nowadays, computers tend not to swap; if your server swaps on a regular basis, you might want to do some tuning. Memory I/O is faster than disk I/0, and the ratio memory I/0 / disk I/0 is more than the ratio cache / memory. I/0.

Maybe not much of a data point, but from the servers with resource problems I've seen, more of them benefitted from getting more memory, than more or faster CPUs. Most computers have more than enough CPU cycles - but usually they can use more main memory.

Abigail


Comment on Re: Out-Of-Date Optimizations? New Idioms? RAM vs. CPU
Re: Re: Out-Of-Date Optimizations? New Idioms? RAM vs. CPU
by Anonymous Monk on Jul 21, 2003 at 08:09 UTC

    Could you recommend any good books/articles/etc on system performance tuning? I've read 'system performance tuning' and 'web performance tuning' from O'Reilly but didn't find them all that useful. Thanks.

      I've seen of useful, or useful looking books about Solaris system performance tuning - most of them printed by SUN. I've found the course material of HP Education quite useful. System performance tuning is hard, and system specific. I would distrust any book that claims to discuss system performance tuning without focussing on a specific OS. I'd also distrust any "cookbook".

      Go for something that spends a lot of time analysing performance problems, that discusses performance measuring tools (like glance for HP-UX), and goes into detail explaining how the system works.

      Abigail

        I was actually considering a few Solaris books, I'll check them out.

        Thanks for the informative (as usual) advice :)

Re: Re: Out-Of-Date Optimizations? New Idioms? RAM vs. CPU
by liz (Monsignor) on Jul 21, 2003 at 08:13 UTC
    True, but nowadays I think of swap as something to keep a computer from crashing during peak loads, rather then something you would need during "normal" operations. If your computer needs swap for "normal" operations (other than as an optimalization), then you have a problem. And indeed, then it doesn't matter because you have bigger problems.

    But I meant more the case when everything can fit in RAM, and you want to make it still faster.

    Liz

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