Messages in this thread | | | Date | Tue, 10 Jan 2006 14:50:05 -0600 | From | Jeffrey Hundstad <> | Subject | Re: 64-bit vs 32-bit userspace/kernel benchmark? Was: Athlon 64 X2 cpuinfooddities |
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David Lang wrote:
> On Tue, 10 Jan 2006, Jeffrey Hundstad wrote: > >> >>> On 1/10/06, Andi Kleen <ak@suse.de> wrote: >>> >>>> On Tuesday 10 January 2006 03:12, Jesper Juhl wrote: >>>> >> ... >> >>>> Ah - how legacy. >>>> >>>> >>> Yeah, but since my distro of choice is 32bit only and I don't much >>> feel like porting it myself or using an unofficial port (slamd64) I'm >>> sticking with a 32bit userspace. And as long as userspace is pure >>> 32bit there doesn't seem to be much point in building a 64bit kernel. >>> And I only have 2GB of RAM, so I don't have a use for the larger 64bit >>> address space. >>> I also don't run any apps that do a lot of math on >32bit numbers, so >>> there's not much gain there either. >>> I guess I would bennefit from the extra GPR's, but then I would at the >>> same time loose a bit by all pointers being 64bit - both lose some >>> disk space due to larger binaries and I'd have increased memory use >>> and less efficient L1/L2 cache use. >>> >>> I don't think there would actually be much gain for me in switching to >>> a 64bit kernel with a 64bit userspace atm. >>> But if I'm wrong I'd of course love to hear about it :) >>> >>> >> >> Has anyone done any actual benchmark tests that show 64-bit vs 32-bit >> environments/distributions with Athlon64 processors. If so, I love >> to see the results. I too elected to stick with 32-bit, using the >> same reasoning/guessing above. > > > remember that benchmarks are all dependant on your workload, but on > some of my workloads (lots of fork-based network services) I've seen a > 50%+ increase by switching from a 32 bit to 64 bit kernel with 32 bit > userspace, and a further 50%+ increase by switching to a 64 bit > userspace. >
Thanks for your response. I'm prob. being stupid here... but does "increase" here mean faster or slower?
> remember that on amd64 systems 64 bit programs have access to twice as > many registers as 32 bit programs. This can be more of a win then the > extra pointer size is a loss.
If you've done other "standard" type of benchmarks between the two please post your results. Also, is there a big hit by using a nearly pure 32-bit environment + the rare 64-bit program when needed?
-- Jeffrey Hundstad
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