freebsd with flexible iflib nic queues
c5239edb98
if_start(). This removes the overlapping data path TX from occuring, which solves quite a number of the potential TX queue races in ath(4). It doesn't fix the net80211 layer TX queue races and it doesn't fix the raw TX path yet, but it's an important step towards this. This hasn't dropped the TX performance in my testing; primarily because now the TX path can quickly queue frames and continue along processing. This involves a few rather deep changes: * Use the ath_buf as a queue placeholder for now, as we need to be able to support queuing a list of mbufs (ie, when transmitting fragments) and m_nextpkt can't be used here (because it's what is joining the fragments together) * if_transmit() now simply allocates the ath_buf and queues it to a driver TX staging queue. * TX is now moved into a taskqueue function. * The TX taskqueue function now dequeues and transmits frames. * Fragments are handled correctly here - as the current API passes the fragment list as one mbuf list (joined with m_nextpkt) through to the driver if_transmit(). * For the couple of places where ath_start() may be called (mostly from net80211 when starting the VAP up again), just reimplement it using the new enqueue and taskqueue methods. What I don't like (about this work and the TX code in general): * I'm using the same lock for the staging TX queue management and the actual TX. This isn't required; I'm just being slack. * I haven't yet moved TX to a separate taskqueue (but the taskqueue is created); it's easy enough to do this later if necessary. I just need to make sure it's a higher priority queue, so TX has the same behaviour as it used to (where it would preempt existing RX..) * I need to re-review the TX path a little more and make sure that ieee80211_node_*() functions aren't called within the TX lock. When queueing, I should just push failed frames into a queue and when I'm wrapping up the TX code, unlock the TX lock and call ieee80211_node_free() on each. * It would be nice if I could hold the TX lock for the entire TX and TX completion, rather than this release/re-acquire behaviour. But that requires that I shuffle around the TX completion code to handle actual ath_buf free and net80211 callback/free outside of the TX lock. That's one of my next projects. * the ic_raw_xmit() path doesn't use this yet - so it still has sequencing problems with parallel, overlapping calls to the data path. I'll fix this later. Tested: * Hostap - AR9280, AR9220 * STA - AR5212, AR9280, AR5416 |
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| Makefile | ||
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| README | ||
| UPDATING | ||
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