On Fri, 2009-08-07 at 18:55 +0200, Ivo van Doorn wrote: > > If we have a lot of frames to transmit at once, for > > instance with fragmentation, it can be an optimisation > > to only tell the DMA engine about them on the last > > fragment/frame to avoid banging the IO too much. This > > patch allows implementation such an optimisation by > > telling the driver when more frames can be expected. > > Wouldn't this be the same as the > if (ieee80211_has_morefrags()) > .. kick queue ... Initially, yes, but I think we should eventually use it for sending out multiple frames after restarting queues etc. For instance after scanning, we could send out a bunch of frames at once. > > Currently, this is used by mac80211 only on fragmented > > frames, but could also be used in the future on other > > frames when the queue was full and there are multiple > > frames pending. > > > > Note that drivers need to be careful when using this > > flag, they need to kick their DMA engines not just > > when this flag is clear, but also when the queue gets > > full so that progress can be made. > > What would a good value be for the threshold? > rt2x00 currently uses 10% of the queue, which means that > 2 or 3 entries are kept available at all times. Well, for fragmentation I think the maximum number of fragments is 9. johannes
Attachment:
signature.asc
Description: This is a digitally signed message part
