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
events.
This is primarily for the TX EDMA and TX EDMA completion. I haven't yet
tied it into the EDMA RX path or the legacy TX/RX path.
Things that I don't quite like:
* Make the pointer type 'void' in ath_softc and have if_ath_alq*()
return a malloc'ed buffer. That would remove the need to include
if_ath_alq.h in if_athvar.h.
* The sysctl setup needs to be cleaned up.
This should eventually be unified with ATH_DEBUG() so I can get both
from one macro; that may take some time.
Add some new probes for TX and TX completion.
The hardware can optionally "filter" frames if successive transmissions
to a given node (ie, "entry in the keycache") fail. That way the hardware
can implement a kind of early abort of all the other frames queued to
that destination, rather than simply trying to TX each frame to that
destination (and failing.)
The background:
* If a frame comes back as being filtered, the hardware didn't try to
TX it (or it was outside the TX burst opportunity.) So, take it as a hint
that some (but not all, see below) frames to the destination may be
filtered.
* If the CLRDMASK bit is set in a TX descriptor, the "filter to this
destination" bit in the keycache entry is cleared and TX to that host
will be unconditionally retried.
* Right now everything has the CLRDMASK bit set, so filtered frames
tend to be aggregates and frames that fall outside of the WME burst
window. It was a bit worse in the past as I had messed up the TX
flags and CLRDMASK wasn't being set on aggregate frames.
The annoying bits:
* It's easy (ish) to do for aggregate session frames - firstly, they
can be retried in any order as long as they're within the BAW, and
there's already a bunch of infrastructure tracking how many frames
the TID has queued to the hardware (tid->hwq_depth.) However, for
frames that bypassed the software queue, hwq_depth doesn't get
incremented. I'll fix that in a subsequent commit.
* For non-aggregate session frames, the only retries that can occur
are ones for sequence numbers that hvaen't successfully been TXed yet.
Since there's no re-ordering going on in non-aggregate sessions, if any
subsequent seqno frames make it out, any filtered frames before that
seqno need to be dropped.
Hence why this initially is just for aggregate session frames.
* Since there may be intermediary frames to the destination that
have CLRDMASK set - for example, any directly dispatched management
frames to that destination - it's possible that there will be some
filtered frames followed up by some non filtered frames. Thus,
it can't be assumed that once you see a filtered frame for the given
destination node, all subsequent frames for all TIDs will be filtered.
Ok, with that in mind:
* Create a per-TID filtered frame queue for frames that the hardware
returns as filtered.
* Track filtered frames per-tid, rather than per-node. It just makes
the locking much easier.
* When a filtered frame appears in the completion function, the node
transitions to "filtered", and all subsequent completed error frames
(filtered or otherwise) are put on the filtered frame queue. The TID
is paused once (during the transition from non-filtered to filtered).
* If a filtered frame retry count exceeds SWMAX_RETRIES, a BAR should be
sent.
* Once all the frames queued to the hardware for the given filtered frame
TID, transition back from filtered frame to non-filtered frame, which
means pre-pending all the filtered frames onto the head of the software
queue, clearing the filtered frame state and unpausing the TID.
Things get quite hairy around handling completion (aggr, non-aggr, norm,
direct-dispatched frames to a hardware queue); whether it's an "error",
"cleanup" or "BAR" state as well as filtered, which order to do things
in (eg do filtered BEFORE checking for BAR, as the filter completion
may be needed to actually transmit a BAR frame.)
This work has definitely reminded me that I have to tidy up all the locking
and remove some of the ridiculous lock/unlock/lock/unlock going on in the
completion functions.
It's also reminded me that I should really split out TID versus hardware TXQ
locking, even if the underlying locking is still the destination hardware TXQ.
Finally, this is all pre-requisite for working on AP mode power save support
(PS-POLL, uAPSD) as well as improving performance to misbehaving nodes (as
they can transition into filter mode, stopping any TX until everything has
caught up.)
Finally (ish) - this should also be done for non-aggregate sessions as
there are still plenty of laptops and mobile devices that don't speak
802.11n but do wish for stable, useful power save AP support where packets
aren't simply dropped. This requires software retransmission for
non-aggregate sessions to be implemented, which includes the caveats I've
mentioned above.
Finally finally - this doesn't yet do anything about the CLRDMASK bit in the
TX descriptor. That's still unconditionally set to 1. I'll debug the
current work (mostly ensuring I haven't busted up the hairy transitions
between BAR, filtered, error (all frames in an aggregate failing) and
cleanup (when transitioning from aggregation -> non-aggregation.))
Finally finally finally - this is all original work by yours truely, rather
than ported from the Atheros internal driver codebase or Linux ath9k.
Tested:
* AR9280, AR5416 in STA mode
* AR9280, AR9130 in hostap mode
* Lots and lots of iperf testing in very marginal and non-marginal conditions,
complete with inducing filtered frames + BAR TX conditions.
The AR9003 series NICs implement a separate RX error to signal that a
Keycache miss occured. The earlier NICs would not set the key index
valid bit.
I'll dig into the difference between "no key index bit set" and "keycache
miss".
ath_start() is called.
This (defaults to 10 frames) gives for a little headway in the TX ath_buf
allocation, so buffer cloning is still possible.
This requires a lot omre experimenting and tuning.
It also doesn't stop a node/TID from consuming all of the available
ath_buf's, especially when the node is going through high packet loss
or only talking at a low TX rate. It also doesn't stop a paused TID
from taking all of the ath_bufs. I'll look at fixing that up in subsequent
commits.
PR: kern/168170
traffic.
* Create sc_mgmt_txbuf and sc_mgmt_txdesc, initialise/free them appropriately.
* Create an enum to represent buffer types in the API.
* Extend ath_getbuf() and _ath_getbuf_locked() to take the above enum.
* Right now anything sent via ic_raw_xmit() allocates via ATH_BUFTYPE_MGMT.
This may not be very useful.
* Add ATH_BUF_MGMT flag (ath_buf.bf_flags) which indicates the current buffer
is a mgmt buffer and should go back onto the mgmt free list.
* Extend 'txagg' to include debugging output for both normal and mgmt txbufs.
* When checking/clearing ATH_BUF_BUSY, do it on both TX pools.
Tested:
* STA mode, with heavy UDP injection via iperf. This filled the TX queue
however BARs were still going out successfully.
TODO:
* Initialise the mgmt buffers with ATH_BUF_MGMT and then ensure the right
type is being allocated and freed on the appropriate list. That'd save
a write operation (to bf->bf_flags) on each buffer alloc/free.
* Test on AP mode, ensure that BAR TX and probe responses go out nicely
when the main TX queue is filled (eg with paused traffic to a TID,
awaiting a BAR to complete.)
PR: kern/168170
add some more BAR debugging logic.
* Change the definition of ath_debug and ath_softc.sc_debug from
int to uint64_t;
* Change the relevant sysctls;
* Add a new BAR TX debugging field;
* Use this in if_ath_tx.
This has been tested by using the sysctl program, which happily allows
for fields > 32 bits to be configured.
call these after rate control selection is done.
The duration/protection code wasn't working - it expected the rix to
be valid. Unfortunately after I moved the rate control selection into
late in the process, the rix value isn't valid and thus the protection/
duration code would get things wrong.
HT frames are now correctly protected with an RTS and for the AR5416,
this involves having the aggregate frames be limited to 8K.
TODO:
* Fix up the DMA sync to occur just before the frame is queued to the
hardware. I'm adjusting the duration here but not doing the DMA
flush.
* Doubly/triply ensure that the aggregate frames are being limited to
the correct size, or the AR5416 will get unhappy when TXing RTS-protected
aggregates.
In a very noisy 2.4GHz environment (with HT/40 enabled, making it worse)
I saw the following occur:
* the air was considered "busy" a lot of the time;
* the cabq time is quite short due to staggered beacons being enabled;
* it just wasn't able to keep up TX'ing CABQ frames;
* .. and the cabq would swallow up all the TX ath_buf's.
This patch introduces a twiddle which allows the maximum cabq depth to be
set, forcing further frames to be dropped.
It defaults to the TX buffer count at the moment, so the default behaviour
isn't changed.
I've also started fleshing out a similar setup for the data path, so
it doesn't swallow up all the available TX buffers and preventing management
frames (such as ADDBA) out.
PR: kern/165895
The hardware (MAC) LED blinking involves a few things:
* Selecting which GPIO pins map to the MAC "power" and "network" lines;
* Configuring the MAC LED state (associated, scanning, idle);
* Configuring the MAC LED blinking type and speed.
The AR5416 HAL configures the normal blinking setup - ie, blink rate based
on TX/RX throughput. The default AR5212 HAL doesn't program in any
specific blinking type, but the default of 0 is the same.
This code introduces a few things:
* The hardware led override is configured via sysctl 'hardled';
* The MAC network and power LED GPIO lines can be set, or left at -1
if needed. This is intended to allow only one of the hardware MUX
entries to be configured (eg for PCIe cards which only have one LED
exposed.)
TODO:
* For AR2417, the software LED blinking involves software blinking the
Network LED. For the AR5416 and later, this can just be configured
as a GPIO output line. I'll chase that up with a subsequent commit.
* Add another software LED blink for "Link", separate from "activity",
which blinks based on the association state. This would make my
D-Link DWA-552 have consistent and useful LED behaviour (as they're
marked "Link" and "Activity."
* Don't expose the hardware LED override unless it's an AR5416 or later,
as the previous generation hardware doesn't have this multiplexing
setup.
* Failall is now named just that.
* Add TX ok and TX fail, for aggregate frame sub-frames.
This will break athstats; a followup commit wil resolve this.
Sponsored by: Hobnob, Inc.
The AR5416 MAC (which shows up in the AR5008, AR9001, AR9002 devices) has
issues with PCI transactions on SMP machines. This work-around enforces
that register access is serialised through a (global for now) spinlock.
This should stop the hangs people have seen with the AR5416 PCI devices
on SMP hosts.
Obtained by: Linux, Atheros
This forces a full reset of the baseband/radio and seems needed to clear
some issues (with Merlin at least) when the baseband gets confused in a
very noisy environment.
Sponsored by: Hobnob, Inc.
and interface resets to be marked as ATH_RESET_DEFAULT, ATH_RESET_FULL,
ATH_RESET_NOLOSS.
Currently a reset is still a reset - ie, all tx/rx frames in the hardware
queues are purged. This means that those frames will be lost to the 11n TX
and RX aggregation state tracking, breaking AMPDU sessions.
The (eventual) new semantics:
* ATH_RESET_DEFAULT:
full reset, this is the default for reset situations
which I haven't yet figured out what they should be.
* ATH_RESET_FULL:
A full reset - for things such as channel changes.
* ATH_RESET_NOLOSS:
Don't flush TX/RX queues - handle pending RX frames and leave TX
frames where they are; restart TX DMA from where it was.
A bunch of the 11n TX aggregation logic wants to traverse lists of buffers
in various ways. In order to provide O(1) behaviour in this instance,
use TAILQs.
This does blow out the memory footprint and CPU cycles slightly for some
of these operations. I may convert some of these back to STAILQs once
the rest of the software transmit queue handling has been stabilised.
Sponsored by: Hobnob, Inc.
* Add a PCU lock, which isn't currently used but will eventually be
used to serialise some of the driver access.
* Add in all the software TX aggregation state, that's kept per-node
and per-TID.
* Add in the software and aggregation state to ath_buf.
* Add in hooks to ath_softc for aggregation state and the (upcoming)
aggregation TX state calls.
* Add / fix the HAL access macros.
Obtained from: Linux, ath9k
Sponsored by: Hobnob, Inc.
Although this may not be what the original sysctl was designed to do,
it feels a bit more "expected".
Before, if ANI is disabled, the initial ANI parameters are still written
to the hardware, even if they're not enabled. "ANI enabled" would then
adjust the noise immunity parameters dynamically. Disabling ANI would
simply leave the existing noise immunity parameters where they are,
and disable the dynamic part.
The problem is that disabling ANI doesn't leave the hardware in
a consistent, predictable state - so asking a user to disable ANI
wouldn't actually reset the NIC to a consistent set of PHY signal
detection parameters, resulting in an unpredictable/unreliable outcome.
This makes it difficult to get reliable debugging information from
the user.
Approved by: re (kib)
rather than global variables.
This specifically allows for debugging to be enabled per-NIC, rather
than globally.
Since the ath driver doesn't know about AH_DEBUG, and to keep the ABI
consistent regardless of whether AH_DEBUG is enabled or not, enable the
debug parameter always but only conditionally compile in the debug
methods if needed.
The ALQ support is currently still global pending some brainstorming.
Submitted by: ssgriffonuser@gmail.com
Reviewed by: adrian, bschmidt
in the RX path when doing 11n and block-ack'ed frames. Apparently, the MAC
will loop over that self-linked descriptor and treat it as "good enough"
for (incorrectly!) ACKing the frames in the block-ack.
Until I figure out how to work around this issue in the future, this counter
will tell me if packet RX processing ever gets to the point where it's
touching the self-linked descriptor. If there's ever enough packets to get
to that point, BA's will be invalid and likely very unhappy.
