Hi... On Thu, Jan 20, 2011 at 10:36, Mag Gam <magawake@xxxxxxxxx> wrote: > Running on Redhat 5.1 if I do, Are you sure you're using that archaic distro? Or are you talking about RHEL 5.1? > dd bs=1024 count=1000000 if=/dev/zero of=/dev/null > > I get around 30Gb/sec Hm, mine is: $ dd bs=1024 count=1000000 if=/dev/zero of=/dev/null 1000000+0 records in 1000000+0 records out 1024000000 bytes (1.0 GB) copied, 1.12169 seconds, 913 MB/s This is on 2.6.36 SMP kernel compiled with gcc version 4.1.2 20080704 (Red Hat 4.1.2-48). > > However, when I do this with 2.6.37 I get close to 5GB/sec what if you use another blocksize, let's say 4K or even 32K? here's mine (again): $ dd bs=4K count=1000000 if=/dev/zero of=/dev/null 1000000+0 records in 1000000+0 records out 4096000000 bytes (4.1 GB) copied, 1.31167 seconds, 3.1 GB/s $ dd bs=32K count=1000000 if=/dev/zero of=/dev/null 1000000+0 records in 1000000+0 records out 32768000000 bytes (33 GB) copied, 4.91775 seconds, 6.7 GB/s see the difference? IMHO it's a matter of what I call "block merge efficiency"....the more you stuff pages (that fits into a "magic" number), the faster I/O you got. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
