On Tue, Dec 31, 2013 at 11:38:27AM +0800, Shaohua Li wrote: > > steal_tags only happens when free tags is more than half of the total tags. > This is too restrict and can cause live lock. I found one cpu has free tags, > but other cpu can't steal (thread is bound to specific cpus), threads which > wants to allocate tags are always sleeping. I found this when I run next > patch, > but this could happen without it I think. > > I did performance test too with null_blk. Two cases (each cpu has enough > percpu > tags, or total tags are limited) haven't performance changes.
This doesn't appear to me to fix anything wrong with the current code (and it'll hurt performance) - we explicitly don't guarantee that all the tags will be available for allocation at any given time, only half of them. Can you explain more how this is being used where you're seeing the issue? And I don't see the other patch in your patch series. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
