Hello, Jan. On Thu, Jul 14, 2016 at 04:35:47PM +0200, Jan Kara wrote: > > > The current use case only need to use the regular lock functions. You are > > > right that future use cases may require an irqsafe version of locks. I can > > > either modify the code now to allow lock type selection at init time, for > > > example, or defer it as a future enhancement when the need arises. What do > > > you think? > > > > The bulk of performance gain of dlist would come from being per-cpu > > and I don't think it's likely that we'd see any noticeable difference > > between irq and preempt safe operations. Given that what's being > > implemented is really low level operations, I'd suggest going with > > irqsafe from the get-go. > > I'm not sure here. i_sb_list for which percpu lists will be used is bashed > pretty heavily under some workloads and the cost of additional interrupt > disabling & enabling may be visible under those loads. Probably not in the > cases where you get a boost from percpu lists but if the workload is mostly > single-threaded, additional cpu cost may be measurable. So IMO we should > check whether a load which creates tons of empty inodes in tmpfs from a > single process doesn't regress with this change. Sure, if it actually matters, we can always create separate preempt / irq variants. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
