Messages in this thread | | | Date | Thu, 31 Dec 2009 17:49:18 +0000 | Subject | Re: Ubuntu 32-bit, 32-bit PAE, 64-bit Kernel Benchmarks | From | Pedro Ribeiro <> |
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On Thu, Dec 31, 2009 at 4:32 PM, Bill Davidsen <davidsen@tmr.com> wrote: > Boaz Harrosh wrote: >> >> On 12/31/2009 04:49 AM, Bill Davidsen wrote: >>> >>> Yuhong Bao wrote: >>>> >>>> Given that Linus was once talking about the performance penalties of PAE >>>> and HIGHMEM64G, perhaps you'd find these benchmarks done by Phoronix of >>>> interest: >>>> http://www.phoronix.com/scan.php?page=article&item=ubuntu_32_pae >>>> >>> I find these tests mirror my own experience with PAE, the benefit of >>> having the nx hardware enabled justifies the few percent drop in performance >>> I was able to find. >>> >>> I find the huge gain in web service hard to believe without a hint why a >>> 64 bit CPU would be 15x faster. The disk, memory, and network wouldn't be >>> faster, and the CPU intensive tests weren't significantly faster, so unless >>> the systems were tuned differently where's the gain? Same feeling about the >>> TP test, an order of magnitude faster on a test running the same application >>> on the same hardware is hard to buy without an explanation. >>> >> >> Why? simple, Memory. This system must have lots of memory (see the >> HIGHMEM64G) so >> lots of IO must be bouncing on a 32bit system, where in 64bit it is >> copy-less. >> > Did you miss the hardware configuration? It was run on a laptop with 4GB and > two little laptop drives. And there was no serious difference between the > non-PAE (sees 3GB) and PAE (sees 4GB) performance. Clearly there's little > enough memory to address in any mode. > >> Just my guess, but I'm not surprised. >> > Eight thousand pages/sec out of a laptop with 5400 rpm drives doesn't > surprise you? Even if every page were copied to somewhere else the speed of > the disk and network are still 1000 times slower. I haven't found details on > this "test" but I'm guessing that the pages are all in memory so the disk is > only used once, maybe even the same page being read each time, and if the > client is on the same machine the "network" is loopback. Not representative > of much of anything in the general case, that. > >>> The only obvious source I can think of is running the test load at >>> 100Mbit on >>> one test and Gbit on another, because I saw an early network driver do >>> just that >>> in negotiations with a switch. >>> > > > -- > Bill Davidsen <davidsen@tmr.com> > "We have more to fear from the bungling of the incompetent than from > the machinations of the wicked." - from Slashdot > -- > 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/ >
The article doesn't mention if a 64-bit kernel with 32-bit userland was used or a 64-bit kernel with 64-bit userland.
Is there any performance benefit in having the former?
Regards, Pedro -- 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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