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Re: abundant memory?

From: Jim Meyering
Subject: Re: abundant memory?
Date: Thu, 24 Jul 2008 11:21:55 +0200

Bruno Haible <address@hidden> wrote:
> Jim Meyering wrote:
>> This sounds like an obvious win for linkedhash-list, in these days of
>> inexpensive RAM and the 8GB hobby system.  Back when I wrote hash.c,
>> data structure size was the primary constraint in the computational
>> geometry applications I cared about.
> Small data structure sizes are still important, because of memory caches:
> There is usually a level-1 cache near the CPU, then a level-2 cache, and then
> only comes the main memory measured in gigabytes. The level-1 cache is often

And then there's L3 cache, and maybe even flash-based cache
before you get to "disk".

No argument from me.

> only a few kilobytes large. You can consider that a memory access to an
> uncached memory location is about 6-8 times slower than a memory access to
> cached memory. (*)
> So, the smaller the data structures, the faster your program will be.
> Bit fields are *not* outdated!

Of course not ;-)

My point was that with our much larger RAM sizes today,
the "right" balance for hash.c may now involve using more
memory to save processing time.

Of course, I don't really expect anyone to make changes to
hash.c and to find time to perform all the profiling that'd
be required for justification.

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