Author: Eugene Nalimov
Date: 09:01:51 02/16/00
Go up one level in this thread
On February 16, 2000 at 03:16:04, Ricardo Gibert wrote: >On February 16, 2000 at 02:54:16, Christophe Theron wrote: > >>On February 16, 2000 at 02:47:16, Ricardo Gibert wrote: >> >>>On February 16, 2000 at 02:12:21, Eugene Nalimov wrote: >>> >>>>On February 16, 2000 at 00:26:19, Christophe Theron wrote: >>>> >>>>>On February 15, 2000 at 22:45:28, Tom Kerrigan wrote: >>>>> >>>>>>On February 15, 2000 at 20:42:43, Ricardo Gibert wrote: >>>>>> >>>>>>>MIPS VR4121 is a 64 bit CPU according to NEC. Look at >>>>>>>http://www.nec.com/Semiconductors/categories/679/981008.html >>>>>> >>>>>>You're right... Hmmm... I wonder what the "64 bit" measures. Maybe memory >>>>>>interface? Because it seems pretty silly to have a full-blown 64-bit embedded >>>>>>processor, when your desktop machine is still 32-bit... >>>>>> >>>>>>-Tom >>>>> >>>>> >>>>>Wait a minute. The VR4121 processor claims pin-to-pin compatibility with the >>>>>VR4111. And the VR4111 is a "false 64 bits" processor. Operations can be done on >>>>>64 bits internally, but the data bus size is 16 or 32 bits. That is, there is a >>>>>serious bottleneck between the processor and the memory when it comes to 64 bits >>>>>values. >>>>> >>>>>I'm not even sure that this processor really supports clean 64 bits operations. >>>>>All the docs I have mention 16 and 32 bits long instructions. How do you perform >>>>>a move immediate with a 64 bits value if your instruction length is limited to >>>>>32 bits? >>>> >>>>IBM/360, as well as IBM/370, also have no instruction "move immediate 32-bit >>>>value"; if you want to load literal that is longer than 12 bits, you have to >>>>load it from memory. Nevertheless it is true 32-bit processor. >>>> >>>>At that MIPS processor, loading/storing 64-bit values can be slower than 32-bit >>>>values - but total impact on performance would be small enough. Small size of >>>>cache is much more important, but I believe Crafty would perform as it's running >>>>on P90-120. >>> >>>Windows 95 Pentium P5-120 159.4 Drystone MIPS >>> >>>Win CE VR4121 131mhz 174 Drystone MIPS >>> >>>So your prediction is not bad. >> >> >>Do you have the Drystone MIPS for the DragonBall EZ? Motorola claims 2.7 for his >>16.58MHz processor, but I wonder if it has been checked by somebody else. >> >>Is there a web site with a compilation of Drystone MIPS for a bunch of popular >>processors? >> >> >> Christophe >> >> >> >> >>> >>>> >>>>Eugene >>>> >>>>>And don't count on the 8Kb internal L1 data cache to store all the data needed >>>>>by Crafty... >>>>> >>>>>A bitboard program looks like a poor choice for this architecture. >>>>> >>>>> >>>>> >>>>> Christophe > >I went to the following site for the Pentium statistic: > >http://performance.netlib.org/performance/html/dhrystone.data.col0.html > >This site does not seem to include statistics for HPC/PPC type CPUs. The VR141 >statistic came from the NEC site. Given manufacturers penchant for exagerated >claims, it must be taken with a grain of salt. Therefore, "rough" equivalence >with the P5-120 seems reasonable. Dhrystone is executed entirely from the cache, plus it have very small data set that fits into cache, too. So, for more typical programs performance will degragate - so I am stuck with my 'p90-p120-level performance estimate'. Eugene
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