Re: filesystem and x86 vs. x86_64 benchmarking...
I'm subscribed to the mailing list, no need to Cc me.
> First of all wall clock time is meaningless when comparing results. When
> you have other processes competing for the CPU the wall clock can rise
> drastically without the test being any slower. Wall clock without % cpu
> usage is meaningless.
Well, the machine was not running X or cron let alone anything else while I
was running the tests, so pretty much all of the tests got 100% of the CPU.
Occasionally I ran "top" to see what the memory consumption looked like.
But since the tests were mainly for my own purposes I didn't make them
overly scientific, you're correct about that.
> Secondly g++ using >1GB ram or temporary files in 64bit mode might not be
> a bug at all but just the extra complexity of optimizing for 64bit. I
> noticed that gcc usualy uses 4 times as much ram in 64bit than
> 32bit. Some worst case sources can increase that easily.
True, and the register allocation would be different as well. Perhaps it's
not a bug. It would be interesting to know if you need double the memory
for comparable (slightly improved?) performance for C++ compilation in
x86_64. I hadn't really considered that. Hopefully it's a bug ;-)
> Looking over the compile tests it looks like a 64bit kernel is faster in
> userspace but wastes about the same time in kernel space, probably
> translating the 32bit syscalls to 64bit. It is too bad you have hardly
> any comparable tests in there. A lot of 32bit tests without 64bit
Yes, I thought I clearly explained my interest was how to set up this
machine to get the best performance for my own purposes. Once it became
clear that 64 bit mode was going to be ineffective for my purposes, I
thought I'd stop wasting my time slowly compiling the same code over and
> And where is the bonie++ test with 64bit kernel? Do any of the FS become
> faster/slower? Actualy I wan't three runs: 32bit kernel, 64bit kernel +
> 32bit userland, 64bit kernel+userland.
I'll run this for one filesystem type. If the differences are noteworthy,
I'll look at the others. Thanks for the suggestion - that's what I was
looking for in posting to this list.
> We all have seen comparisons between FSes and that is a rather boring
Sorry to bore you, that certainly was not my intention.
Dale E. Martin - email@example.com