From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kurt Fitzner Subject: Re: [parisc-linux] B132L outperforms C160 - 64-bit userland needed? Date: Wed, 17 Aug 2005 23:27:24 -0600 Message-ID: <43041C3C.2080704@excelcia.org> References: <4301B090.9040405@excelcia.org> <20050817061913.GA8761@colo.lackof.org> <430384FE.6080105@excelcia.org> <20050817194058.GA3378@netfall.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 To: parisc-linux@lists.parisc-linux.org Return-Path: In-reply-to: <20050817194058.GA3378@netfall.com> List-Id: parisc-linux developers list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: parisc-linux-bounces@lists.parisc-linux.org Andrew Sharp wrote: > So stop ignoring that difference. Cache thrashing is > a real, and sad, international problem. Take those benchmarks that > produce slower results on a P4/2MB cache processor than they do on a > P4/512KB processor. Same motherboard, OS, benchmark. Only difference, > 4x bigger cache. If the processor is spending more time loading cache > lines, it's spending less time computating. Cache systems are designed to > improve the performance of general computing tasks, and many benchmarks > fall outside that realm. Andrew Sharp wrote: Ok, I bit the bullet. I took an image of the hard drive to restore later, and installed HPUX. I then obtained gcc 3.4.3 from the HPUX software porting archive and recompiled the benchmark with that. Raw data is at the end. Next off, for nbench running on a C160/HPUX I see a memory throughput increase of 2.67X, integer calc increase of 1.4X, and floating point increase of 2.24X when compared to the C160/Linux. The data show exactly the sort of performance increase that I originally expected to see when comparing a B132L and C160. Strongly improved integer and vastly improved memory performance. The performance issue on my C160/Linux was not due cache line loading/thrashing. It's not due to slower memory, nor due to some odd conflaguration of C160 architecture changes and an old benchmark program. I am convinced that there is some problem in Linux - probably some otherwise minor thing. Whatever it is, it's sucking performance from PA8000 systems - and perhaps other PA8x00 ones. What really locked it in for me that it's an OS issue, aside from the dramatic results below, is what happened when I changed optimization switches in HPUX. I see the exact same 2% drop in performance when I go from binaries compiled as 1.1/7300 to 2.0/8000 that I saw in Linux. Same compiler on both OSes producing code that reacts exactly the same way when optimizations are changed. I'm convinced - how can I convince the group? I'm quite willing to give ssh access to my machines for the results to be verified. I should be able to swap between HPUX/Linux fairly quickly now that I have images of both. Kurt. p.s. I installed HPUX in 64-bit mode. Which, so I'm told, should have decreased my performance. I'd like to get my C160 running Linux in 64-bit mode, but I can't. :( ------------------------------------------------------------------ TEST : Iterations/sec. : Old Index : New Index : : Pentium 90* : AMD K6/233* --------------------:------------------:-------------:------------ NUMERIC SORT : 99.68 : 2.56 : 0.84 STRING SORT : 14.104 : 6.30 : 0.98 BITFIELD : 2.1599e+07 : 3.70 : 0.77 FP EMULATION : 8.8339 : 4.24 : 0.98 FOURIER : 2660.2 : 3.03 : 1.70 ASSIGNMENT : 1.8832 : 7.17 : 1.86 IDEA : 116.73 : 1.79 : 0.53 HUFFMAN : 121.4 : 3.37 : 1.08 NEURAL NET : 2.81 : 4.51 : 1.90 LU DECOMPOSITION : 116.6 : 6.04 : 4.36 ================================================================== OS : HP-UX B.11.11 C compiler : gcc version 3.4.3 MEMORY INDEX : 1.120 INTEGER INDEX : 0.827 FLOATING-POINT INDEX: 2.414 _______________________________________________ parisc-linux mailing list parisc-linux@lists.parisc-linux.org http://lists.parisc-linux.org/mailman/listinfo/parisc-linux