This problem goes away when plugged in - to be more specific it has to do with sata link power management. Now I understand I will have lower speed while on min_power, but is it normal to have such a big difference with and without O_DIRECT?
echo max_performance > /sys/class/scsi_host/host0/link_power_management_policy Timing O_DIRECT disk reads: 594 MB in 3.00 seconds = 197.71 MB/sec Timing buffered disk reads: 558 MB in 3.01 seconds = 185.53 MB/sec echo min_power > /sys/class/scsi_host/host0/link_power_management_policy Timing O_DIRECT disk reads: 410 MB in 3.01 seconds = 136.13 MB/sec Timing buffered disk reads: 212 MB in 3.01 seconds = 70.33 MB/sec -- Slow disk read performance https://bugs.launchpad.net/bugs/575722 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
