Comment 0 for bug 601986

Running
Description: Ubuntu 10.04 LTS
Release: 10.04
Linux jim-nb 2.6.32-24-generic #38~pre201007021000-Ubuntu SMP Sun Jul 4 06:49:54 UTC 2010 i686 GNU/Linux
But problem seen on all kernels tried.

Boot process hangs for ~7 minutes, then machine starts. Booting with init=/bin/init and running "hdparm -t /dev/sda5" (sda5 is my ubuntu fs) gives ~500kB/sec. Completing the upstart process brings disk up to ~40 MB/sec.

When " bootchart" is installed machine boots in 23 seconds! Resume from hibernate works. Investigation has shown that a compiled C program with an infinite loop, when run in the background from init-top in the intramfs will also cure the slow boot. The C-program saturates on of the two processors of the Atom N450 (~100% CPU1). It appears that bootchart works its magic by simply saturating one CPU. After boot, running the inifinite loop program brings disk performance (as reported by hdparm) up from 40 MB/sec to 70 MB/sec.

Adding highres=off nohz=off to the kernel command line cures slow disk problem but machine runs hot with lower battery life. Adding nohpet to the kernel command line also cures the slow boot but not the resume from suspend.

I suspect that the problem lies with ahci.ko or libata. Changing the BIOS disk parameter from ahci to compatibility also cures the problem... but screws up the existing Windows partition.

Tried the linux-image-2.6.35-020635rc3-generic_2.6.35-020635rc3_i386.deb kernel. It acts the same.