On Mon, Sep 7, 2009 at 7:17 PM, Steven Rostedt<rostedt@xxxxxxxxxxx> wrote: > On Mon, 2009-09-07 at 17:14 -0700, Stephen Hemminger wrote: >> On Mon, 7 Sep 2009 15:58:50 -0700 >> "Luis R. Rodriguez" <mcgrof@xxxxxxxxx> wrote: >> >> > A while ago I had read about an effort to consider removing tasklets >> > [1] or at least trying to not use them. I'm unaware of the progress in >> > this respect but since reading that article have always tried to >> > evaluate whether or not we need tasklets on wireless drivers. I have >> > also wondered whether work in irq context in other parts of the kernel >> > can be moved to process context, a curious example being timers. I'll >> > personally be trying to using only process context on bottom halves on >> > future drivers but I figured it may be a good time to ask how serious >> > was avoiding tasklets or using wrappers in the future to avoid irq >> > context is or is it advised. Do we have a general agreement this is a >> > good step forward to take? Has anyone made tests or changes on a >> > specific driver from irq context to process context and proven there >> > are no significant advantages of using irq context where you would >> > have expected it? >> > >> > Wireless in particular should IMHO not require taskets for anything >> > time sensitive that I can think about except perhaps changing channels >> > quickly and to do that appropriately also process pending RX frames >> > prior to a switch. It remains to be seen experimentally whether or not >> > using a workqueue for RX processing would affect the time to switch >> > channels negatively but I doubt it would be significant. I hope to >> > test that with ath9k_htc. >> > >> > What about gigabit or 10 Gigabit Ethernet drivers ? Do they face any >> > challenges which would yet need to be proven would not face issues >> > when processing bottom halves in process context? >> > >> > [1] http://lwn.net/Articles/239633/ >> > >> > Luis >> > -- >> > To unsubscribe from this list: send the line "unsubscribe netdev" in >> > the body of a message to majordomo@xxxxxxxxxxxxxxx >> > More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> Why not use NAPI, which is soft irq? Almost all 1G and 10G drivers >> use NAPI. >> >> Process context is too slow. > > Well, I'm hoping to prove the opposite. I'm working on some stuff that I > plan to present at Linux Plumbers. I've been too distracted by other > things, but hopefully I'll have some good numbers to present by then. What day in specific was this planned for at Plumbers? Luis -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
