It seems that compiling won't be necessary after all :-) I'm a bit mad at myself for not checking the obvious culprit when disk performance is bad: DMA. I have a SATA disk, but it was visible as hda (probably some historic legacy from previous distributions). I think that the proper standard is to call SATA disks as sdX.
In -7 kernel when I checked it with hdparm I saw that DMA is enabled and I could manually switch it on/off. In newer kernels however, hdparm shows that DMA is off and I can't switch it on manually: # hdparm -d1 /dev/hda /dev/hda: setting using_dma to 1 (on) HDIO_SET_DMA failed: Operation not permitted using_dma = 0 (off) So I thought about telling the kernel to recognize the disk as sda, not hda. I passed "root=/dev/sda1" on kernel command line in LILO and the kernel indeed changed the device name from hda to sda. How convenient :-) Now, with /dev/sda I can't change DMA mode either, but this is expected on SATA/SCSI (DMA is on by default). However, the performance is back to normal, or even slightly better than before: $ uname -a Linux fafik 2.6.24-12-generic #1 SMP Wed Mar 12 23:01:54 UTC 2008 i686 GNU/Linux $ time dd if=rh73.vdi of=/dev/null 1177609+0 records in 1177609+0 records out 602935808 bytes (603 MB) copied, 14.1059 s, 42.7 MB/s real 0m14.113s user 0m0.780s sys 0m2.304s So to sum this up -- something must have changed between -7 and -11 in the way "hdX" disks handle DMA. When using SATA, it seems that sdX is the only proper way of naming them. Don't know if anything must be done about that. I suppose that a fresh Hardy install would choose sdX naming by default, in my case it was different because of upgrades from older dists. Thanks for help! -- [hardy][regression] disk I/O makes the system very slow and unresponsive https://bugs.launchpad.net/bugs/210502 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
