[Bug 217815] Re: Installation stalls randomly until a key is pressed

Colin King colin.king at ubuntu.com
Mon Apr 21 11:21:46 BST 2008


A couple of points worth mulling over to corner this one..

1. Is the "hanging" a function of memory size - for example, the buffer
cache filling up after a certain amount of time and then pdflush kicking
in very aggressively doing dirty data writing backs as fast as it can.
In which case, one may see the system resume again after a (long) period
of time once pdflush is complete.  It may be worth tweaking with the
/proc/sys/vm/dirty* options to see if this trips the problem more
frequently. Also, it may be worth seeing if doing the install with small
memory kvm virtual machines shows this problem earlier than large memory
virtual machines just to see if it is a buffer cache write back cpu
starvation issue.

2. From my understanding dd is being used to zero the encrypted disk.
Does changing the dd block size to a very large size trip this bug
earlier as one gets more throughput than the normal (small) block size
default?

3. Is the hanging resumed by an external interrupt (keyboard, mouse)
because of the scheduler boosts interactive sessions temporarily and
hence interfering (in a positive way) to the balancing of the encryption
kernel space thread, dd and pdflush?

-- 
Installation stalls randomly until a key is pressed
https://bugs.launchpad.net/bugs/217815
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