So, let me clarify a bit: i did the same test in 3 different configuration: "cat bigfile >/dev/null" 3 configuration were 1) Machine A (the slow one) from the big partition (1000gb) - got 5mb/s 2) Machine A from the small partition - got 16mb(s 3) Machine B from 300gb partition - got 28mb/s Machine A: AthlonXP 800 -Via KT600 - SATA disk western digital - direct ext3 filesystems (no raid-no lvm-no nothing) Machine B: Pentium 2 350 - i440bx - seagate IDE drive - direct ext3 filesystems I also did another test: putting a cpu intensive process in the background with nice -n 20. The test showed the process was not being executed almost at all, so those %wa cpu cycles are somehow cpu cycles since they dont let other processes execute. (in fact when i do stuff with the disk my system became incredibly slow) Finally i tried the test you suggested me root@rivendell:~# time dd if=/dev/zero of=/tmp/testfile bs=1024000 count=1000 1000+0 records in 1000+0 records out 1024000000 bytes (1,0 GB) copied, 16,9609 s, 60,4 MB/s real 0m17.119s user 0m0.010s sys 0m12.890s with a sample cpu usage of: Cpu(s): 0.7%us, 15.0%sy, 0.0%ni, 76.1%id, 6.6%wa, 0.0%hi, 1.7%si, 0.0%st root@rivendell:~# time dd if=/dev/zero of=/local/testfile bs=1024000 count=1000 1000+0 records in 1000+0 records out 1024000000 bytes (1,0 GB) copied, 23,3957 s, 43,8 MB/s real 0m23.898s user 0m0.010s sys 0m14.090s with a sample cpu usage of Cpu(s): 1.3%us, 50.7%sy, 0.0%ni, 0.0%id, 45.4%wa, 0.7%hi, 2.0%si, 0.0%st ( / was the 30gb partition, /local the 900gb) On 5/18/08, Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote: >> real 5m16.352s >> user 0m0.132s >> sys 0m6.244s > > So the CPU usage is ok > >> root@ubuntu:/media/disk/movies# ls -la Lo\ squalo.avi >> -rw-r----- 1 1000 1001 1559521280 2008-03-30 06:37 Lo squalo.avi >> >> it means roughly those old 5mb/sec. >> In the meanwhile i checked with top, and all the cpu cycles were taken >> by the disk (about 98.0%wa and 0.0%id) > > 98.0%wa - wait time, not CPU time. > > Its still a very slow copy rate unless the disks are on the same IDE > channel. How is the disk set up - ext3 direct or via raid/lvm ? > > Also is a copy of the movie to /dev/null slow or fast, ditto a copy > from /dev/zero to disk of that sort of size ? > > Alan > -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
