Make sure the size of the raw[] array in the lro_address union is
correctly set at compile time, so that static code analysis tools
do not report undefined behaviour.
MFC after: 1 week
Sponsored by: NVIDIA Networking
The layout of the structure ends up depending on whether the including
file includes opt_inet.h and opt_inet6.h, so different compilation units
can end up seeing different versions of the structure. Fix this by
unconditionally defining the address fields.
As a side effect, this eliminates some duplication in the kernel's CTF
type graph.
Reviewed by: rscheff, tuexen
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34242
TCP per RFC793 has 4 reserved flag bits for future use. One
of those bits may be used for Accurate ECN.
This patch is to include these bits in the LRO code to ease
the extensibility if/when these bits are used.
Reviewed By: hselasky, rrs, #transport
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D34127
LRO was willing to merge ACK and non-ACK packets together. This
can cause incorrect th_ack values to be reported up the stack.
While non-ACKs are quite unlikely to appear in practice, LRO's
behaviour is against the spec. Make LRO unwilling to merge
packets with different TH_ACK flag values in order to fix the
issue.
Found by: Sysunit test
Differential Revision: https://reviews.freebsd.org/D33775
Reviewed by: rrs
To check if it needed to regenerate a packet's header before
sending it up the stack, LRO was checking if more than one payload
had been merged into the packet. This failed in the case where
a single payload was merged with one or more pure ACKs. This
results in lost ACKs.
Fix this by precisely tracking whether header regeneration is
required instead of using an incorrect heuristic.
Found with: Sysunit test
Differential Revision: https://reviews.freebsd.org/D33774
Reviewed by: rrs
Encrypted and un-encrypted traffic needs to be coalesced separately.
Split the 16-bit lro_type field in the address information into two
8-bit fields, and then use the last 8-bit field for flags, which among
other indicate if the received mbuf is encrypted or un-encrypted.
Differential Revision: https://reviews.freebsd.org/D31377
Reviewed by: gallatin
MFC after: 1 week
Sponsored by: NVIDIA Networking
HPTS drives both rack and bbr, and yet there have been many complaints
about performance. This bit of work restructures hpts to help reduce CPU
overhead. It does this by now instead of relying on the timer/callout to
drive it instead use user return from a system call as well as lro flushes
to drive hpts. The timer becomes a backstop that dynamically adjusts
based on how "late" we are.
Reviewed by: tuexen, glebius
Sponsored by: Netflix Inc.
Differential Revision: https://reviews.freebsd.org/D31083
Recently we had a rewrite to tcp_lro.c that was tested but one subtle change
was the move to a less precise timestamp. This causes all kinds of chaos
in tcp's that do pacing and needs to be fixed to use the more precise
time that was there before.
Reviewed by: mtuexen, gallatin, hselasky
Sponsored by: Netflix Inc
Differential Revision: https://reviews.freebsd.org/D30695
This change makes the TCP LRO code more generic and flexible with regards
to supporting multiple different TCP encapsulation protocols and in general
lays the ground for broader TCP LRO support. The main job of the TCP LRO code is
to merge TCP packets for the same flow, to reduce the number of calls to upper
layers. This reduces CPU and increases performance, due to being able to send
larger TSO offloaded data chunks at a time. Basically the TCP LRO makes it
possible to avoid per-packet interaction by the host CPU.
Because the current TCP LRO code was tightly bound and optimized for TCP/IP
over ethernet only, several larger changes were needed. Also a minor bug was
fixed in the flushing mechanism for inactive entries, where the expire time,
"le->mtime" was not always properly set.
To avoid having to re-run time consuming regression tests for every change,
it was chosen to squash the following list of changes into a single commit:
- Refactor parsing of all address information into the "lro_parser" structure.
This easily allows to reuse parsing code for inner headers.
- Speedup header data comparison. Don't compare field by field, but
instead use an unsigned long array, where the fields get packed.
- Refactor the IPv4/TCP/UDP checksum computations, so that they may be computed
recursivly, only applying deltas as the result of updating payload data.
- Make smaller inline functions doing one operation at a time instead of
big functions having repeated code.
- Refactor the TCP ACK compression code to only execute once
per TCP LRO flush. This gives a minor performance improvement and
keeps the code simple.
- Use sbintime() for all time-keeping. This change also fixes flushing
of inactive entries.
- Try to shrink the size of the LRO entry, because it is frequently zeroed.
- Removed unused TCP LRO macros.
- Cleanup unused TCP LRO statistics counters while at it.
- Try to use __predict_true() and predict_false() to optimise CPU branch
predictions.
Bump the __FreeBSD_version due to changing the "lro_ctrl" structure.
Tested by: Netflix
Reviewed by: rrs (transport)
Differential Revision: https://reviews.freebsd.org/D29564
MFC after: 2 week
Sponsored by: Mellanox Technologies // NVIDIA Networking
a further CPU enhancements for compressed acks. These
are acks that are compressed into an mbuf. The transport
has to be aware of how to process these, and an upcoming
update to rack will do so. You need the rack changes
to actually test and validate these since if the transport
does not support mbuf compression, then the old code paths
stay in place. We do in this commit take out the concept
of logging if you don't have a lock (which was quite
dangerous and was only for some early debugging but has
been left in the code).
Sponsored by: Netflix Inc.
Differential Revision: https://reviews.freebsd.org/D28374
to add BBR. These changes make it so you can get an
array of timestamps instead of a compressed ack/data segment.
BBR uses this to aid with its delivery estimates. We also
now (via Drew's suggestions) will not go to the expense of
the tcb lookup if no stack registers to want this feature. If
HPTS is not present the feature is not present either and you
just get the compressed behavior.
Sponsored by: Netflix Inc
Differential Revision: https://reviews.freebsd.org/D21127
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
No functional change intended.
"qsort()".
The kernel's "qsort()" routine can in worst case spend O(N*N) amount of
comparisons before the input array is sorted. It can also recurse a
significant amount of times using up the kernel's interrupt thread
stack.
The custom sorting routine takes advantage of that the sorting key is
only 64 bits. Based on set and cleared bits in the sorting key it
partitions the array until it is sorted. This process has a recursion
limit of 64 times, due to the number of set and cleared bits which can
occur. Compiled with -O2 the sorting routine was measured to use
64-bytes of stack. Multiplying this by 64 gives a maximum stack
consumption of 4096 bytes for AMD64. The same applies to the execution
time, that the array to be sorted will not be traversed more than 64
times.
When serving roughly 80Gb/s with 80K TCP connections, the old method
consisting of "qsort()" and "tcp_lro_mbuf_compare_header()" used 1.4%
CPU, while the new "tcp_lro_sort()" used 1.1% for LRO related sorting
as measured by Intel Vtune. The testing was done using a sysctl to
toggle between "qsort()" and "tcp_lro_sort()".
Differential Revision: https://reviews.freebsd.org/D6472
Sponsored by: Mellanox Technologies
Tested by: Netflix
Reviewed by: gallatin, rrs, sephe, transport
This is kinda critical to the performance when the CPU is slow and
network bandwidth is high, e.g. in the hypervisor.
Reviewed by: rrs, gallatin, Dexuan Cui <decui microsoft com>
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D5765
So that callers could react accordingly.
Reviewed by: gallatin (no objection)
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D5695
ACK aggregation limit is append count based, while the TCP data segment
aggregation limit is length based. Unless the network driver sets these
two limits, it's an NO-OP.
Reviewed by: adrian, gallatin (previous version), hselasky (previous version)
Approved by: adrian (mentor)
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D5185
- Add optimizing LRO wrapper which pre-sorts all incoming packets
according to the hash type and flowid. This prevents exhaustion of
the LRO entries due to too many connections at the same time.
Testing using a larger number of higher bandwidth TCP connections
showed that the incoming ACK packet aggregation rate increased from
~1.3:1 to almost 3:1. Another test showed that for a number of TCP
connections greater than 16 per hardware receive ring, where 8 TCP
connections was the LRO active entry limit, there was a significant
improvement in throughput due to being able to fully aggregate more
than 8 TCP stream. For very few very high bandwidth TCP streams, the
optimizing LRO wrapper will add CPU usage instead of reducing CPU
usage. This is expected. Network drivers which want to use the
optimizing LRO wrapper needs to call "tcp_lro_queue_mbuf()" instead
of "tcp_lro_rx()" and "tcp_lro_flush_all()" instead of
"tcp_lro_flush()". Further the LRO control structure must be
initialized using "tcp_lro_init_args()" passing a non-zero number
into the "lro_mbufs" argument.
- Make LRO statistics 64-bit. Previously 32-bit integers were used for
statistics which can be prone to wrap-around. Fix this while at it
and update all SYSCTL's which expose LRO statistics.
- Ensure all data is freed when destroying a LRO control structures,
especially leftover LRO entries.
- Reduce number of memory allocations needed when setting up a LRO
control structure by precomputing the total amount of memory needed.
- Add own memory allocation counter for LRO.
- Bump the FreeBSD version to force recompilation of all KLDs due to
change of the LRO control structure size.
Sponsored by: Mellanox Technologies
Reviewed by: gallatin, sbruno, rrs, gnn, transport
Tested by: Netflix
Differential Revision: https://reviews.freebsd.org/D4914
Add a last-modified timestamp to each LRO entry and provide an interface
to flush all inactive entries. Drivers decide when to flush and what
the inactivity threshold should be.
Network drivers that process an rx queue to completion can enter a
livelock type situation when the rate at which packets are received
reaches equilibrium with the rate at which the rx thread is processing
them. When this happens the final LRO flush (normally when the rx
routine is done) does not occur. Pure ACKs and segments with total
payload < 64K can get stuck in an LRO entry. Symptoms are that TCP
tx-mostly connections' performance falls off a cliff during heavy,
unrelated rx on the interface.
Flushing only inactive LRO entries works better than any of these
alternates that I tried:
- don't LRO pure ACKs
- flush _all_ LRO entries periodically (every 'x' microseconds or every
'y' descriptors)
- stop rx processing in the driver periodically and schedule remaining
work for later.
Reviewed by: andre
Significantly update tcp_lro for mostly two things:
1) introduce basic support for IPv6 without extension headers.
2) try hard to also get the incremental checksum updates right,
especially also in the IPv4 case for the IP and TCP header.
Move variables around for better locality, factor things out into
functions, allow checksum updates to be compiled out, ...
Leave a few comments on further things to look at in the future,
though that is not the full list.
Update drivers with appropriate #includes as needed for IPv6 data
type in LRO.
Sponsored by: The FreeBSD Foundation
Sponsored by: iXsystems
Reviewed by: gnn (as part of the whole)
MFC After: 3 days
