On Tue, Dec 24, 2002 at 11:07:39AM -0600, Ronald W. Heiby wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Monday, December 23, 2002, 2:38:57 PM, Ronald wrote: > > As an experiment, I've copied my raw data and compilation app to > > another system with 1 GB of RAM, a 4 GB swap partition, and SCSI > > drives that show about 50 MB/sec buffered read throughput. It will be > > interesting to see how fast that finishes. The original system is > > an HP desktop box, running with a 1.6 GHz P4. This other system is a > > Dell server configuration running a pair of 1 GHz P3 (Coppermine) > > processors. (The data compile process is not multi-threaded.) Anyway, > > I would guess that if cpu bound, the experiment will take longer, but > > if memory/disk/swap bound, the experiment will take less time. > > The experiment concluded. The dual P3 system with SCSI drives is > running RH 8.0 kernel 2.4.18-14smp, versus the P4 system running RH > 8.0 kernel 2.4.18-18.8.0. The elapsed time was 11 hours 7 minutes. > > For the experiment, ran the data compilation under "time -v", and > learned that the job got 5% of the cpu time during its run. This says > to me that cpu time is not the main factor in performance. There were > several million page faults. Since the same executable was used both > places, it's not likely to be a compiler problem. (The executable was > *not* statically linked.) > > In summary, using the same hardware (P4) on ext2 filesystems, my job > went from less than 7 hours to more than 48 hours. At the same time, > the job runs in about 11 hours on a dual P3 with SCSI drives and a bit > more RAM. The differences I see that might be accounting for the big > performance hit: > > 1) Kernel Version (memory management / paging, code and algorithms) > 2) 8.0 increased memory footprint vs 7.2 (???) leading to more paging > > Any ideas? Is your process doing lots of disk I/O? If so, tell us about the filesystem. Is it ext2 or ext3? Or something else? I've seen filesystem choice give drastic performance changes on high disk I/O processes. Cheers, -- Javier Gostling Av. Kennedy 5757, of. 1502 Ingeniero de Sistemas Las Condes, Santiago, Chile Virtualia S.A. Fono: +56 (2) 202-6264 x 130 jgostling@virtualia.cl Fax: +56 (2) 342-8763
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