Re: Crunch time -- the musical. (2.5 merge candidate list 1.5)

["Martin J. Bligh" <mbligh@aracnet.com>]

>> I thought this problem is well understood! For some reasons independent of
>> my patch you have to boot your machines with the "notsc" option. This
>> leaves the cache_decay_ticks variable initialized to zero which my patch
>> doesn't like. I'm trying to deal with this inside the patch but there is
>> still a small window when the variable is zero. In my opinion this needs
>> to be fixed somewhere in arch/i386/kernel/smpboot.c. Booting a machine
>> with cache_decay_ticks=0 is pure nonsense, as it switches off cache
>> affinity which you absolutely need! So even if "notsc" is a legal option,
>> it should be fixed such that it doesn't leave your machine without cache
>> affinity. That would anyway give you a falsified behavior of the O(1)
>> scheduler.

> EIP is at task_to_steal+0x118/0x260

This turned out to be:

weight = (jiffies - tmp->sleep_timestamp)/cache_decay_ticks;

So I guess that window is still biting you. I'll see if I can fix it properly.

M.