Messages in this thread | | | Date | Wed, 4 Dec 2002 12:19:47 +0100 | From | Pavel Machek <> | Subject | Re: [PATCH] Start of compat32.h (again) |
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Hi!
> > BTW, I bet your dynamic relocation tables are a bit larger too. > > Somewhat, but does it matter? They are not kept in memory anyways. > > It's all about how much data a ld.so relocation has to touch. But > preloading will help out here, even though that isn't in wide spread > use just yet. > > And I was talking about user stack usage, not the kernel kind > :-) > > Andi, do something very simple like run -m32 vs -m64 microbenchmarks, > I bet -m32 beats -m64 in all the lmbench lat_proc tests. On sparc64 > it's (on a 2-way SMP system): > > -m32 fork+exit: 360.8328 microseconds > -m32 fork+execve: 1342.2213 microseconds > -m32 fork+/bin/sh: 5497.0149 microseconds > > -m64 fork+exit: 553.9076 microseconds > -m64 fork+execve: 1904.6315 microseconds > -m64 fork+/bin/sh: 6268.6932 microseconds > > NOTE: make sure you change /bin/sh to be 32-bit/64-bit as > appropriate in the tests above. > > So what is this on x86_64? :-) I think lat_proc is great becuase it > shows pure libc overhead in continually relocating the exit() > etc. symbols in the child for fork+exit, for example. > > The reason I'm making such a stink about this is that I don't want > people believing that "the code generation improvements due to the > extra x86_64 registers available nullifies the bloat cost from > going to 64-bit"
Actually, it tends to nullify the bloat cost and then make it few percent faster... For most of spec2000 modulo two or three cache-bound tests that are 50% slower :-(. Pavel -- Worst form of spam? Adding advertisment signatures ala sourceforge.net. What goes next? Inserting advertisment *into* email? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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