This has been disabled until now because there hasn't been any supported
device which has this feature. Since the AR9287 is the first device to
support it, and since now the HAL has functional AR9287+11n support,
flip this on.
AR9287 EEPROM layout.
The AR9287 only supports 2ghz, so I've removed the 5ghz code (but left
the 5ghz edge flags in there for now) and hard-coded the 2ghz-only
path.
Whilst I'm there, fix a typo (ar9285->ar9287.)
This meets basic TX throughput testing - iperf TX tests == 27-28mbit in 11g,
matching the rest of my 11g kit.
I'm assuming for now that the AR9287 is only open-loop TX power control
(as mine is) so I've hard-coded the attach path to fail if the NIC is
not open-loop.
This greatly simplifies the TX calibration path and the amount of code
which needs to be ported over.
This still isn't complete - the rate calculation code still needs to be
ported and it all needs to be glued together.
Obtained from: Linux ath9k
It isn't linked into the build because it's missing the TX power
and PDADC programming code.
This code is mostly based on the ath9k codebase, compared against
the Atheros codebase as appropriate.
What's implemented:
* probe/attach
* EEPROM board value programming
* RX initial calibration
* radio channel programming
* general MAC / baseband setup
* async fifo setup
* open-loop tx power calibration
What's missing before it can be enabled by default:
* TX power / calibration setting code
* closed-loop tx power calibration routines
* TSF2 handling
* generic timer support from ath9k
Obtained from: Atheros, ath9k
values for the commands, compared to the internal command values
(HAL_ANI_CMD.)
My eventual aim is to make the HAL_ANI_CMD internal enum match
the public API and then remove all this messiness.
This now allows HAL_CAP_INTMIT users to use a public HAL_CAP_INTMIT_
enum rather than magic constants.
The only magic constants currently used by if_ath are "enable" and
"present". Some local tools of mine allow for direct, manual fiddling
of the ANI variables and I'll convert these to use the public enum API
before I commit them.
of the ANI statistics and committing some tools which use these.
* Change HAL_ANI_* commands _back_ to be numerical, rather than a
bitmap;
* modify access to the ANI control bitmap to convert a command to
a bitmap;
* Fix the ANI noise immunity fiddling for CCK errors - it wasn't
checking whether noise immunity was disabled or not.
which did AR5212 specific initialisation. This would cause some slight
silliness when enabling/disabling ANI.
Just to be completely correct - and to ensure the phy error mask/RX filter
register isn't incorrectly played with - make the ANI control function a
method, have it set appropriately for AR5212/AR5416, and call that from the
ANI control interface.
This should hopefully make it clearer to developers what is going on
and when TPC is being hacked on, make it obvious why it isn't working for
series 1, 2, 3.
I won't flip on setting TX power for TX series 1, 2, 3 until I've done
some further testing with Kite to ensure it doesn't break anything.
(Before people ask - yes, TPC is only needed for 5ghz regdomains and
yes, Kite is a 2.4ghz only chip, but there are potential use cases
for 2ghz TPC. I just need to sit down and ensure it's supported and
functional.)
control the antenna control bits for the four TX series and the
TPC settings for TX series 1, 2, 3.
The specifics:
* The TPC setting for TX series 0 is handled in ctl0.
* TPC is currently disabled, so the per-packet TX power is
set via the global per-rate TX power register, not per packet.
* The antenna control bits don't matter for AR5416 and later
so they should stay 0 (which they currently do); they may
be set for Kite but as there's no TX diversity supported
at the moment (it requires the NIC to be built with an
external antenna switch, matching how antenna diversity
is done on legacy NICs), so again keep them 0.
This is in preparation for supporting per-rate TPC on the
AR5416 and later. The Kite (and soon to come Kiwi) code
sets ctl8-11 to 0x0, which doesn't have any effect at
the moment. When TPC is enabled it would result in the
second, third and fourth TX series attmpts to be done with
a TX power of 0. This commit doesn't change that; it'll
be followed up with some commits to properly set the TPC
registers appropriately.
the multicast key search support for AR5212, AR5416 and later.
The general HAL routine ath_hal_getcapability() implement checking this
but it's overridden by a check in ar5212_misc:ar5212GetCapability().
This restores the later functionality in case it's found to be broken
in any of the 11n chipsets.
Since the returned NF will be -ve, checking for <= 0 is not good
enough. For now, check whether it equals 0 or -1; a future commit
will tidy this mess up and have it return HAL_BOOL instead.
The eeprom Get method should return HAL_OK if fastclock is enabled in the
EEPROM. It was returning the opposite of what it should have.
Submitted by: Matthew Fleming <mdf356@gmail.com>
The code assumed it could return HAL_OK, HAL_EINVAL and other
HAL_STATUS types; so it shouldn't be declared as returning HAL_BOOL.
This commit was brought to you by the Clang compiler.
Submitted by: Matthew Fleming <mdf356@gmail.com>
I've tested this locally and it does indeed read and attach to an AR9287
EEPROM. But a lot more code needs to be ported over to the HAL before
the AR9287 is functional.
I'm importing this separate from the rest of the codebase (and unlinked from
the build for now) in case someone wishes to begin fiddling with porting
the rest of the code over from Linux ath9k.
Obtained from: Linux ath9k
is totally disabled.
The Atheros HAL code does this for Sowl/Howl but not for Owl (AR5416) where
RIFS is disabled by default.
This seems to quieten the occasional baseband hang I've been seeing with
the AR9160 in STA mode under constant heavy traffic load.
Obtained from: Atheros
Some files keep the SUN4V tags as a code reference, for the future,
if any rewamped sun4v support wants to be added again.
Reviewed by: marius
Tested by: sbruno
Approved by: re
for the AR9280 based NICs if it's actually enabled.
Some of the OLC code was erroneously called during setup
and calibration. This may have caused some incorrect behaviour.
table which contains the per-rate target TX power.
This code is shared between the v14 eeprom board setup (AR5416, AR9160,
AR9280) and will also be used by the upcoming Kite (AR9287) support.
* grab the main, alt and selected LNA config
* add some optional / disabled logging code
* add a check to reject packets with an invalid main rssi too,
in case the alt is the active receive chain and main is -ve.
Note: The software-controlled combined diversity code is still disabled.
environments.
In setups where NF calibration can take a while, don't load the CCA
and kick off a new NF calibration if the previous one hasn't yet
completed. This shouldn't happen unless the environment is noisy but
those exist (hi phk!).
Here, if the previous NF hasn't completed when ar5416LoadNf() is run
(which reads the NF), it skips updating the history buffer, loading
the NF CCA array and kicking off the next NF cal. It's hoped it'll
occur in the next long calibration interval.
Obtained from: Atheros, ath9k, my local HAL
This is taking quite a while for some people in some situations
(eg AR5418 in phk's Abusive Radio Environment).
Instead, the rest of the calibration related code should
ensure that a NF calibration has occured before reading NF
values and kicking off another NF calibration.
The channel should also likely be marked as "noisy" (CWINT)
if the NF calibration takes too long.
* Correct some of the silicon revision checks to match what
the Atheros HAL does. (See [1] below.)
* Move the PA cal and init cal method assignment to -after-
the mac version/revision IDs are stored. The AR9285 init
cal was never being called.
* Enable ANI.
Note Kite 1.0 and 1.1 were prototypes that shouldn't be seen
in the wild. Linux ath9k simply removed the prototype code from
their codebase. I'm going to leave it in there for now but
make it conditionally compilable in the future.
Obtained from: Atheros
from Atheros as to what/when this is supposed to be enabled.
Using the default RX fast diversity settings seems to help quite
a bit.
Whilst I'm here, change the prototype to return HAL_BOOL rather than int.
For now, the diversity settings are controlled by 'txantenna',
-not- rxantenna. This is because the earlier chipsets had
controllable TX diversity; the RX antenna setting twiddles
the default antenna register. I'll try sort that stuff out at
some point.
Call the antenna switch function from the board setup function
so scans, channel changes, mode changes, etc don't set the
diversity back to a default state too far from what's intended.
Things to todo:
* Squirrel away the last antenna diversity/combining parameters
and restore them during board setup if HAL_ANT_VARIABLE is
defined. That way scans, etc don't reset the diversity settings.
* Add some more public facing statistics, rather than what's
simply logged under HAL_DEBUG_DIVERSITY.
For now, the fixed antenna settings behave better than variable
settings for me. I have some further fiddling to do..
Obtained from: Atheros
The macro which I incorrectly copied into ah_internal.h assumed
that it'd be called with an AR_SREV_MERLIN_20() check to ensure
it was only enabled for Merlin (AR9280) silicon revision 2.0 or
later.
Trouble is, the 5GHz fast clock EEPROM flag is only valid for
EEPROM revision 16 or greater; it's assumed to be enabled
by default for Merlin rev >= 2.0. This meant it'd be incorrectly
set for AR5416 and AR9160 in 5GHz mode.
This would have affected non-default clock timings such as SIFS,
ACK and slot time. The incorrect slot time was very likely wrong
for 5ghz mode.
* Modify AR_SREV_MERLIN_20() to match the Atheros/Linux ath9k behaviour -
its supposed to match Merlin 2.0 and later Merlin chips.
AR_SREV_MERLIN_20_OR_LATER() matches AR9280 2.0 and later chips
(AR9285, AR9287, etc.)
for the given channel is available.
It isn't used yet; ar5416GetWirelessModes() needs to be taught
about this rather than assuming HT20/HT40 is available.
This seems to make the AR9160 behave better during heavy scanning,
where before it'd hang and require a hard reset to recover.
Obtained From: Linux ath9k, Atheros
modifying AR_DIAG_SW.
There's a hardware workaround which sets disabling some errors
early at startup and clears said bits before the PCU begins
receiving - it does this to avoid RX descriptor status errors.
It's possible these bits aren't being completely properly twiddled
in all instances; but in particular if the diag_reg HAL variable
is set it won't be setting these bits correctly. I'll review this
at some point.
* Disable multicast search on mac address and key id - the driver
doesn't use it at the moment and thus adhoc may be broken for
merlin and later.
* Change this to be for Merlin 1.0 (which from what I understand
wasn't ever publicly released) to be more correct.
Apparently all three RX chains need to be enabled before initial calibration
is done, even if only two are configured.
Reorder the alt chain swap bit to match what the Atheros HAL is doing.
Obtained From: ath9k, Atheros
* Shuffle some of the capability numbers around to match the
Atheros HAL capability IDs, just for consistency.
* Add some new capabilities to FreeBSD from the Atheros
HAL which will be be shortly used when new chipsets are added
(HAL SGI-20 support is for Kiwi/AR9287 support); for
TX aggregation (MBSSID aggregate support, WDS aggregation
support); CST/GTT support for carrier sense/TX timeout.
channel when the channel is HT/40.
The new ANI code (primarily for the AR9300/AR9400) in ath9k sets this
register but the ANI code for the previous 11n chips didn't set this.
Unlike ath9k, only set this for HT/40 channels.
Obtained From: ath9k
These describe FCC/Japan channel and DFS behaviour.
The AR9285 and later chips don't set these bits in the eeprom, the correct
behaviour is to just assume all five bits are enabled.
specific.
The Atheros HAL and FreeBSD HAL share the same capabilities up
until HAL_CAP_11D, where things begin to diverge.
I'll look at tidying these up soon.
Obtained from: Atheros
* Add Howl (ar9130) to the list of chips that have DFS/BB/MAC hangs
* Don't treat unknown BB hangs as fatal; ath9k/Atheros HAL don't
treat it as such.
* Add HAL_DEBUG_DFS to the debug fields in ath_hal/ah_debug.h
The BB hang check simply loops over an observation register checking
for a stuck state engine, but it can happen under high traffic
conditions. Ath9k and the Atheros HAL simply log a debug message and
continue.
Private to FreeBSD:
* Add HAL_DEBUG_HANG to the debug fields
* Change the hang debugging to HAL_DEBUG_HANG rather than HAL_DEBUG_DFS
like in the Atheros HAL.
Obtained from: Atheros
For now, these are equivalent macros. AR_SREV_OWL{X}_OR_LATER
will later change to exclude Howl (AR9130) in line with what
the Atheros HAL does.
This should not functionally change anything.
Obtained from: Atheros
A quick story, which is partially documented in the commit.
The silicon revision in Linux ath9k and the Atheros HAL use an
AR_SREV_REVISION mask of 0x07.
FreeBSD's HAL uses the AR5212 AR_SREV_REVISION mask of 0x0F.
Thus the OWL silicon revisions were coming through as 0xA, 0xB,
0xC, rather than 0x0, 0x1 and 0x2.
My ath9k-sourced AR_SREV_OWL_<X> macros were thus using the wrong
silicon revision values and wouldn't correctly match.
This commit does a few things:
* Change the AR_SREV_OWL_<x> macros to use the AR_SREV_REVISION_OWL_*
values, not AR_XSREV_REVISION_OWL macros;
* Disable AR_XSREV_REVISION_OWL_* values;
* Modify the IS_5416 to properly check the MAC is OWL, rather than
potentially matching on non-OWL revisions (which shouldn't happen
unless there's a silicon revision of higher than 0x9 in a later
chip..)
* Add a couple more macros from the Atheros HAL for compatibility.
The main difference now is that the Atheros HAL defines
AR_SREV_OWL_{20,22}_OR_LATER subtly differently - it fails on all HOWL
silicon. The AR_SREV_5416_*_OR_LATER macros match on the relevant OWL
version -and- all HOWL versions, along with subsequent versions.
A subsequent commit is going to migrate the uses of AR_SREV_OWL_X_OR_LATER
to AR_SREV_5416_X_OR_LATER to match what's going on in the Atheros HAL.
There's only two uses of AR_SREV_OWL_X_OR_LATER which currently don't
apply to FreeBSD but it may do in the future.
Yes, it's all confusing!
Quoting the ath9k commit message:
At present the noise floor calibration is processed in supported
control and extension chains rather than required chains.
Unnccesarily doing nfcal in all supported chains leads to
invalid nf readings on extn chains and these invalid values
got updated into history buffer. While loading those values
from history buffer is moving the chip to deaf state.
This issue was observed in AR9002/AR9003 chips while doing
associate/dissociate in HT40 mode and interface up/down
in iterative manner. After some iterations, the chip was moved
to deaf state. Somehow the pci devices are recovered by poll work
after chip reset. Raading the nf values in all supported extension chains
when the hw is not yet configured in HT40 mode results invalid values.
Reference: https://patchwork.kernel.org/patch/753862/
Obtained from: Linux ath9k
The checks should function as follows:
* AR_SREV_<silicon> : check macVersion matches that version id
* AR_SREV_<silicon>_<revision> : check macVersion and macRevision match
the version / revision respectively
* AR_SREV_<silicon>_<revision>_OR_LATER: check that
+ if the chip silicon version == macVersion, enforce revision >= macRevision
+ if the chip silicon version > macVersion, allow it.
For example, AR_SREV_MERLIN() only matches AR9280 (any revision),
AR_SREV_MERLIN_10() would only match AR9280 version 1.0, but
AR_SREV_MERLIN_20_OR_LATER() matches AR9280 version >= 2.0 _AND_
any subsequent MAC (So AR9285, AR9287, etc.)
The specific fixes which may impact users:
* if there is Merlin hardware > revision 2.0, it'll now be correctly
matched by AR_SREV_MERLIN_20_OR_LATER() - the older code simply
would match on either Merlin 2.0 or a subsequent MAC (AR9285, AR9287, etc.)
* Kite version 1.1/1.2 should now correctly match. As these macros
are used in the AR9285 reset/attach path, and it's assumed that the
hardware is kite anyway, the behaviour shouldn't change. It'll only
change if these macros are used in other codepaths shared with
older silicon.
Obtained from: Linux ath9k, Atheros
The AR9130 is an AR9160/AR5416 family WMAC which is glued directly
to the AR913x SoC peripheral bus (APB) rather than via a PCI/PCIe
bridge.
The specifics:
* A new build option is required to use the AR9130 - AH_SUPPORT_AR9130.
This is needed due to the different location the RTC registers live
with this chip; hopefully this will be undone in the future.
This does currently mean that enabling this option will break non-AR9130
builds, so don't enable it unless you're specifically building an image
for the AR913x SoC.
* Add the new probe, attach, EEPROM and PLL methods specific to Howl.
* Add a work-around to ah_eeprom_v14.c which disables some of the checks
for endian-ness and magic in the EEPROM image if an eepromdata block
is provided. This'll be fixed at a later stage by porting the ath9k
probe code and making sure it doesn't break in other setups (which
my previous attempt at this did.)
* Sprinkle Howl modifications throughput the interrupt path - it doesn't
implement the SYNC interrupt registers, so ignore those.
* Sprinkle Howl chip powerup/down throughout the reset path; the RTC methods
were
* Sprinkle some other Howl workarounds in the reset path.
* Hard-code an alternative setup for the AR_CFG register for Howl, that
sets up things suitable for Big-Endian MIPS (which is the only platform
this chip is glued to.)
This has been tested on the AR913x based TP-Link WR-1043nd mode, in
legacy, HT/20 and HT/40 modes.
Caveats:
* 2ghz has only been tested. I've not seen any 5ghz radios glued to this
chipset so I can't test it.
* AR5416_INTERRUPT_MITIGATION is not supported on the AR9130. At least,
it isn't implemented in ath9k. Please don't enable this.
* This hasn't been tested in MBSS mode or in RX/TX block-aggregation mode.
Writing the TX power registers is the same between all of these chips
and later NICs (AR9287, AR9271 USB, etc.) so this will reduce code
duplication when those NICs are added to the HAL.
spurious (and fatal) interrupt errors.
One user reported seeing this:
Apr 22 18:04:24 ceres kernel: ar5416GetPendingInterrupts: fatal error,
ISR_RAC 0x0 SYNC_CAUSE 0x2000
SYNC_CAUSE of 0x2000 is AR_INTR_SYNC_LOCAL_TIMEOUT which is a bus timeout;
this shouldn't cause HAL_INT_FATAL to be set.
After checking out ath9k, ath9k_ar9002_hw_get_isr() clears (*masked)
before continuing, regardless of whether any bits in the ISR registers
are set. So if AR_INTR_SYNC_CAUSE is set to something that isn't
treated as fatal, and AR_ISR isn't read or is read and is 0, then
(*masked) wouldn't be cleared. Thus any of the existing bits set
that were passed in would be preserved in the output.
The caller in if_ath - ath_intr() - wasn't setting the masked value
to 0 before calling ath_hal_getisr(), so anything that was present
in that uninitialised variable would be preserved in the case above
of AR_ISR=0, AR_INTR_SYNC_CAUSE != 0; and if the HAL_INT_FATAL bit
was set, a fatal condition would be interpreted and the chip was
reset.
This patch does the following:
* ath_intr() - set masked to 0 before calling ath_hal_getisr();
* ar5416GetPendingInterrupts() - clear (*masked) before processing
continues; so if the interrupt source is AR_INTR_SYNC_CAUSE
and it isn't fatal, the hardware isn't reset via returning
HAL_INT_FATAL.
This doesn't fix any underlying errors which trigger
AR_INTR_SYNC_LOCAL_TIMEOUT - which is a bus timeout of some
sort - so that likely should be further investigated.
It's also marked inactive by the initvals, and enabled after
the baseband/PLL has been configured, but before the RF
registers have been programmed.
The origin and reason for this particular change is currently unknown.
Obtained from: Linux ath9k
Antenna diversity on the >= AR5416 is implemented differently than the
AR5212 and previous chips. So for now, and not to confuse things, just
disable it for now.
diversity.
This is bit dirty and likely should be revised at a later date,
with an eye to unifying/tidying up the whole diversity setup
and allowing developers to do "tricky stuff" as they desire.
For now, this works.
* add a new method, specifically for doing per-RX packet
antenna diversity
* set that HAL method only if it's Kite and a Kite chip that
does diversity.
* add a diversity flag to the HAL debugging section
* add a check to make sure the kite diversity code doesn't run
on boards that don't require it, as not all Kite chips will
implement it.
* add some debug statements when the diversity code makes
changes to the antenna diversity/combining setup.
Note: this HAL currently only supports the AR9285.
From Linux ath9k:
The problem is that when the attenuation is increased,
the rate will start to drop from MCS7 -> MCS6, and finally
will see MCS1 -> CCK_11Mbps. When the rate is changed b/w
CCK and OFDM, it will use register desired_scale to calculate
how much tx gain need to change.
The output power with the same tx gain for CCK and OFDM modulated
signals are different. This difference is constant for AR9280
but not AR9285/AR9271. It has different PA architecture
a constant. So it should be calibrated against this PA
characteristic.
The driver has to read the calibrated values from EEPROM and set
the tx power registers accordingly.
ctl/ext noise floor values.
This routine doesn't check to see whether the radio is MIMO
capable - instead, it simply returns either the raw values,
the "nominal" values if the raw values aren't yet available
or are invalid, or '0' values if there's no valid channel/
no valid MIMO values.
Callers are expected to verify the radio is a MIMO radio
(which for now means it's an 11n chipset, there are non-11n
MIMO chipsets out there but I don't think we support them,
at least in MIMO mode) before exporting the MIMO values.
upper-level HAL.
Right now the per-chain noise floor values aren't used anywhere in
the upper-level HAL, so the driver currently has no real reference
to compare the per-chain RSSI values to.
This is needed before per-chain RSSI values (for ctl and ext radios)
are can be thrown upstairs to the net80211 code.
From the ath9k source:
==
11N: we can no longer afford to self link the last descriptor.
MAC acknowledges BA status as long as it copies frames to host
buffer (or rx fifo). This can incorrectly acknowledge packets
to a sender if last desc is self-linked.
==
Since this is useful for pre-AR5416 chips that communicate PHY errors
via error frames rather than by on-chip counters, leave the support
in there, but disable it for AR5416 and later.
Introduce the AHB glue for Atheros embedded systems. Right now it's
hard-coded for the AR9130 chip whose support isn't yet in this HAL;
it'll be added in a subsequent commit.
Kernel configuration files now need both 'ath' and 'ath_pci' devices; both
modules need to be loaded for the ath device to work.
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.
I'll clear how it's supposed to work with Bernhard and then look
at enabling this in the correct situations.
But this -does- enable HT RTS protection (using the appropriate legacy
rates) if this bit of code is enabled.
by default.
Adventourous souls with an AR9220/AR9280 or later and who have a device
that sends PS-POLL frames may wish to try tinkering with this option and
get back to me.
Linux ath9k only enables this for AR9280 and later NICs; so
create a capability for it so it isn't enabled for earlier
NICs.
Enabling hardware PS-POLL support will come in a later commit
and will be disabled by default.
Even though they map to setting the error filter register,
ath9k also writes them untouched to AR_RX_FILTER.
The Force-BSSID match bit can stay high, as it maps to a
misc mode register setting rather than an RX filter bit.
The phyerr, radar and bssid-match bits aren't real bits, they map
to enabling bits in other registers. Move those out of the way of
valid RX filter bits.
Add a few new fields from ath9k - compba, ps-poll, mcast-bcast-all.
the channel width is ni->ni_chw, which is set to the negotiated channel
width. ni->ni_htflags is the capability, rather than the negotiated
value.
Teach both the TX path and the sample rate module about this.
This seems to work fine for STA but not HT/20 AP mode.
Further discussion with net80211 people will need to take place
to ensure that the right flags are set based on the negotiated
capabilities of the remote peer, rather than whatever the local
parameters are.
Sending short-gi frames in 20mhz may work on some chips but
it certainly isn't supported on anything currently supported
by the HAL; and sending HT40 frames in HT20 mode just plain
won't work.
settings, it seems that our defines are backwards and don't match what
is in the EEPROM documentation or internal driver.
The ath9k code used to have a bitfield here, rather than a uint8_t, and
there were #defines used to swap the order based on the endian of the
platform - this wasn't because of nybble or bit ordering of the
underlying host but because of what the compiler was doing.
This may be the reason for the backwards field numbers, as ath9k had
similar issues.
the AR9285 so I'll leave it off for that.
Ath9k sources indiciate that one of the ANI modes interferes with
RIFS detection, so match ath9k and disable that.
* The existing interrupt mitigation code didn't mitigate anything - the
per-packet TX/RX interrupts are still occuring. It's possible this
worked for the AR5416 but not any later chipsets; I'll investigate and
update as needed.
* Set both the RX and TX threshold registers whilst I'm at it.
This is verified to work on the AR9220 and AR9160. I'm leaving it off
by default in case it's truely broken, but I need to have it enabled
when doing 11n testing or interrupt loads exceed 10,000 interrupts/sec.
