Hi Alan, hi all so far, i did some more tests. First of all, i'm using ext3 filesystem (and it might happen it's very slow, according with my tests results) What i did: Trying ubuntu Hardy LiveCD (to check it's not because 1) im using a hand made compiled kernel 2) i might have removed some package which is actually needed for disk performances 3) the upgrade screwed something ) So far, from LiveCD i did the same i did before, that is: root@ubuntu:/media/disk/movies# time cat Lo\ squalo.avi >/dev/null real 5m16.352s user 0m0.132s sys 0m6.244s 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) ok so not my fault. Maybe ext3? my volumes looks like: root@rivendell:~# df Filesystem 1K-blocks Used Available Use% Mounted on /dev/sda1 28834716 17088924 10281068 63% / [...] /dev/sda3 931618688 613099244 314519444 67% /local So i got a 30gb partition, and a 900gb partition (roughly). I tried to copy the file into the smaller partition ( into / ) and: root@rivendell:/# time cp -rf /local/movies/Lo\ squalo.avi / real 6m21.978s user 0m0.150s sys 0m18.170s root@rivendell:/# time cat /Lo\ squalo.avi >/dev/null real 1m33.913s user 0m0.150s sys 0m5.370s root@rivendell:/# time cat /local/movies/Lo\ squalo.avi >/dev/null real 6m13.549s user 0m0.230s sys 0m5.930s During this tests, the first and the last command still showed like 98.0%wa while with the second, (reading the file from the / fs) i had about 50-60%wa and some idle cycles (about 20% or so, sometimes 0% but not always) with about 16mb/sec transfer rate (which is still slow, to me.. again, hdparm -tT shows: root@rivendell:/# hdparm -tT /dev/sda /dev/sda: Timing cached reads: 476 MB in 2.00 seconds = 237.68 MB/sec Timing buffered disk reads: 220 MB in 3.02 seconds = 72.80 MB/sec ) This test shows to me that it might be a filesystem issue, but still, is it possible it's so expensive? i mean, even from a 30gb partition (which is the norm) reading operations take almost all the cpu power (even if it's finally faster). Ok, my cpu is not lighting fast (AthlonXP 800mhz) but i had almost better performances on a pentiumII 350mhz and 320gb IDE hard drive (debian testing on ext3). do you have any clue about what could i do to improve fs performances? Thank you in advance and excuse me for the boring mail! Paolo On 5/1/08, Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote: > On Thu, 1 May 2008 21:16:24 +0200 > Paolo <paoletto@xxxxxxxxx> wrote: > >> Umh.. >> >> Thank you for your answer! >> Actually, i think the same. Hdparm tests shows good results. > > hdparm results mean the disk setup is ok > >> what i dont get is why the cpu load raise to keep idle to 0% like if >> it was pio mode, even if it is in udma6.. >> What else could be, other than the libata layer not setted in dma >> (which is not)? > > Anything above the disk driver layer - file system, block queue setup > or something happening which causes a lot of I/O in small chunks (which > ruins a disks performance). This is usually distro level stuff so best > analysed by the distribution people. > >> ps: no, im not using LVM. But ubuntu is using their uuid stuff in >> fstab to boot which i quite dont know at all.. >> maybe that? > > No that wouldn't explain it at all. The uuid/fstab stuff is just boot > time stuff so doesn't get in the way. > > What file system are you using ? > -- 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
