James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> writes: > > When the hang occurred, kswapd basically pegged one core in 100% system > time. This looks like there's something specific to sandybridge that > causes this type of bad interaction. I was wondering if it could be > something to to with a scheduling problem in turbo mode? Once kswapd > goes flat out, the core its on will kick into turbo mode, which causes > it to get preferentially scheduled there, leading to the live lock. Sounds unlikely to me. Turbo mode does not affect the scheduler and the cores are (reasonably) independent. > The only evidence I have to support this theory is that when I reproduce > the problem with PREEMPT, the core pegs at 100% system time and stays > there even if I turn off the load. However, if I can execute work that > causes kswapd to be kicked off the core it's running on, it will calm > back down and go to sleep. Turbo mode just makes the CPU faster, but it should not change the scheduler decisions. -Andi -- ak@xxxxxxxxxxxxxxx -- Speaking for myself only -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>