Most of the functions designed to read a counter over a period go through
the same complex loop and only differ in the way they use the returned
values, so it was worth implementing all this into freq_ctr_total() which
returns the total number of events over a period so that the caller can
finish its operation using a divide or a remaining time calculation. As
a special case, read_freq_ctr_period() doesn't take pending events but
requires to enable an anti-flapping correction at very low frequencies.
Thus the function implements it when pend<0.
Thanks to this function it will be possible to reimplement the other ones
as inline and merge the per-second ones with the arbitrary period ones
without always adding the cost of a 64 bit divide.
This variable almost never changes and is read a lot in time-critical
sections. threads_want_rdv_mask is read very often as well in
thread_harmless_end() and is almost never changed (only when someone
uses thread_isolate()). Let's move both to read_mostly.
This one only contains the list of per-thread kqueue FDs, and is used
a lot during updates. Let's mark it read_mostly to avoid false sharing
of FDs placed at the extremities.
This one only contains the list of per-thread epoll FDs, and is used
a lot during updates. Let's mark it read_mostly to avoid false sharing
of FDs placed at the extremities.
Some pointer to arrays such as fdtab, fdinfo, polled_mask etc are never
written to at run time but are used a lot. fdtab accesses appear a lot in
perf top because ha_used_fds is in the same cache line and is modified
all the time. This patch moves all these read-mostly variables to the
read_mostly section when defined. This way their cache lines will be
able to remain in shared state in all CPU caches.
Some variables are mostly read (mostly pointers) but they tend to be
merged with other ones in the same cache line, slowing their access down
in multi-thread setups. This patch declares an empty, aligned variable
in a section called "read_mostly". This will force a cache-line alignment
on this section so that any variable declared in it will be certain to
avoid false sharing with other ones. The section will be eliminated at
link time if not used.
A __read_mostly attribute was added to compiler.h to ease use of this
section.
HA_SECTION() is used as an attribute to force a section name. This is
required because OSX prepends "__DATA, " in front of the declaration.
HA_SECTION_START() and HA_SECTION_STOP() are used as post-attribute on
variable declaration to designate the section start/end (needed only on
OSX, empty on others).
For platforms with an obsolete linker, all macros are left empty. It would
possibly still work on some of them but this will not be needed anyway.
Due to length restrictions on OSX the initcall sections are called "i_"
there while they're called "init_" on other OSes. However the start and
end of sections are still called "__start_init_" and "__stop_init_",
which forces to have distinct code between the OSes. Let's switch everyone
to "i_" and rename the symbols accordingly.
The trace() function is convenient to avoid calling trace() when traces
are not enabled, but there starts to be some callers which place complex
expressions in their trace calls, which results in all of them to be
evaluated before being passed as arguments to the trace() function. This
needlessly wastes precious CPU cycles.
Let's change the function for a macro, so that the arguments are now only
evaluated when the surce has traces enabled. However having a generic
macro being called "trace()" can easily cause conflicts with innocent
code so we rename it "_trace".
Just doing this has resulted in a 2.5% increase of the HTTP/1 request rate.
Interestingly, all arrays used to declare patterns were read-write while
only hard-coded. Let's mark them const so that they move from data to
rodata and don't risk to experience false sharing.
Now travis should only run on cron, on non-amd64, with a configuration that
only has the standard features enabled. This should reduce the number of
valuable build minutes consumed while providing as much value as possible.
In mux_pt_io_cb(), if a connection error or a shutdown is detected, the mux
is destroyed. Thus we must be careful to not use it in a trace message once
destroyed.
No backport needed. This patch should fix the issue #1220.
As for the other muxes, traces are now supported in the pt mux. All parts of
the multiplexer is covered by these traces. Events are splitted by
categories (connection, stream, rx and tx).
In traces, the first argument is always a connection. So it is easy to get
the mux context (conn->ctx). The second argument is always a conn-stream and
mau be NUUL. The third one is a buffer and it may also be NULL. Depending on
the context it is the request or the response. In all cases it is owned by a
channel. Finally, the fourth argument is an integer value. Its meaning
depends on the calling context.
Released version 2.4-dev16 with the following main changes :
- CLEANUP: dev/flags: remove useless test in the stdin number parser
- MINOR: No longer rely on deprecated sample fetches for predefined ACLs
- MINOR: acl: Add HTTP_2.0 predefined macro
- BUG/MINOR: hlua: Detect end of request when reading data for an HTTP applet
- BUG/MINOR: tools: fix parsing "us" unit for timers
- MINOR: server/bind: add support of new prefixes for addresses.
- MINOR: log: register config file and line number on log servers.
- MEDIUM: log: support tcp or stream addresses on log lines.
- BUG/MEDIUM: log: fix config parse error logging on stdout/stderr or any raw fd
- CLEANUP: fd: remove FD_POLL_DATA and FD_POLL_STICKY
- MEDIUM: fd: prepare FD_POLL_* to move to bits 8-15
- MEDIUM: fd: merge fdtab[].ev and state for FD_EV_* and FD_POLL_* into state
- MINOR: fd: move .linger_risk into fdtab[].state
- MINOR: fd: move .cloned into fdtab[].state
- MINOR: fd: move .initialized into fdtab[].state
- MINOR: fd: move .et_possible into fdtab[].state
- MINOR: fd: move .exported into fdtab[].state
- MINOR: fd: implement an exclusive syscall bit to remove the ugly "log" lock
- MINOR: cli/show-fd: slightly reorganize the FD status flags
- MINOR: atomic/arm64: detect and use builtins for the double-word CAS
- CLEANUP: atomic: add an explicit _FETCH variant for add/sub/and/or
- CLEANUP: atomic: make all standard add/or/and/sub operations return void
- CLEANUP: atomic: add a fetch-and-xxx variant for common operations
- CLEANUP: atomic: add HA_ATOMIC_INC/DEC for unit increments
- CLEANUP: atomic/tree-wide: replace single increments/decrements with inc/dec
- CLEANUP: atomic: use the __atomic variant of BTS/BTR on modern compilers
- MINOR: atomic: implement native BTS/BTR for x86
- MINOR: ist: Add `istappend(struct ist, char)`
- MINOR: ist: Add `istshift(struct ist*)`
- MINOR: ist: Add `istsplit(struct ist*, char)`
- BUG/MAJOR: fd: switch temp values to uint in fd_stop_both()
- MINOR: opentracing: register config file and line number on log servers
- MEDIUM: resolvers: add support of tcp address on nameserver line.
- MINOR: ist: Rename istappend() to __istappend()
- CLEANUP: htx: Make http_get_stline take a `const struct`
- CLEANUP: ist: Remove unused `count` argument from `ist2str*`
- CLEANUP: Remove useless malloc() casts
This argument is not being used inside the function (and the functions
themselves are unused as well) and not documented. Its purpose is not clear.
Just remove it.
This patch re-works configuration parsing, it removes the "server"
lines from "resolvers" sections introduced in commit 56fc5d9eb:
MEDIUM: resolvers: add supports of TCP nameservers in resolvers.
It also extends the nameserver lines to support stream server
addresses such as:
resolvers
nameserver localhost tcp@127.0.0.1:53
Doing so, a part of nameserver's init code was factorized in
function 'parse_resolvers' and removed from 'post_parse_resolvers'.
In commit 9533a7038 new parameters have been added to the declaration
of function parse_logsrv().
This patch should be backported to all branches where the OpenTracing
filter is located.
With latest commit f50906519 ("MEDIUM: fd: merge fdtab[].ev and state
for FD_EV_* and FD_POLL_* into state") one occurrence of a pair of
chars was missed in fd_stop_both(), resulting in the operation to
fail if the upper flags were set. Interestingly it managed to fail
2 tests in all setups in the CI while all used to work fine on my
local machines. Probably that the reason is that the chars had enough
room above them for the CAS to fail then refill "old" overwriting the
upper parts of the stack, and that thanks to this the subsequent tests
worked. With ASAN being used on lots of tests, it very likely caught
it but used to only report failed tests with no more info.
No backport is needed, as this was never released nor backported.
The current BTS/BTR operations on x86 are ugly because they rely on a
CAS, so they may be unfair and take time to converge. Fortunately,
where they are currently used (mostly FDs) the contention is expected
to be rare (mostly listeners). But this also limits their use to such
few low-load cases.
On x86 there is a set of BTS/BTR instructions which help for this,
but before the FD's state migrated to 32 bits there was little use of
them since they do not exist in 8 bits.
Now at least it makes sense to use them, at the very least in order
to significantly reduce the code size (one BTS instead of a CMPXCHG
loop). The implementation relies on modern gcc's ability to return
condition flags and limit code inflation and register spilling. The
fall back is retained on the old implementation for all other situations
(inappropriate target size or non-capable compiler). The code shrank
by 1.6 kB on the fast path.
As expected, for now on up to 4 threads there is no measurable difference
of performance.
Probably due to the result of an old copy-paste, HA_ATOMIC_BTS/BTR were
still implemented using the __sync_* builtins instead of the more
modern __atomic_* which allow to specify the memory model. Let's update
this to use the newer there and also implement the relaxed variants
(which are not used for now).
This patch replaces roughly all occurrences of an HA_ATOMIC_ADD(&foo, 1)
or HA_ATOMIC_SUB(&foo, 1) with the equivalent HA_ATOMIC_INC(&foo) and
HA_ATOMIC_DEC(&foo) respectively. These are 507 changes over 45 files.
Most ADD/SUB callers use them for a single unit (e.g. refcounts) and
it's a pain to always pass ",1". Let's add them to simplify the API.
However we currently don't add any return value. If needed in the future
better report zero/non-zero than a real value for the sake of efficiency
at the instruction level.
The fetch_and_xxx variant is often missing for add/sub/and/or. In fact
it was only provided for ADD under the name XADD which corresponds to
the x86 instruction name. But for destructive operations like AND and
OR it's missing even more as it's not possible to know the value before
modifying it.
This patch explicitly adds HA_ATOMIC_FETCH_{OR,AND,ADD,SUB} which
cover these standard operations, and renames XADD to FETCH_ADD (there
were only 6 call places).
In the future, backport of fixes involving such operations could simply
remap FETCH_ADD(x) to XADD(x), FETCH_SUB(x) to XADD(-x), and for the
OR/AND if needed, these could possibly be done using BTS/BTR.
It's worth noting that xchg could have been renamed to fetch_and_store()
but xchg already has well understood semantics and it wasn't needed to
go further.
In order to make sure these ones will not be used anymore in an expression,
let's make them always void. New callers will now be forced to use the
explicit _FETCH variant if required.
Currently our atomic ops return a value but it's never known whether
the fetch is done before or after the operation, which causes some
confusion each time the value is desired. Let's create an explicit
variant of these operations suffixed with _FETCH to explicitly mention
that the fetch occurs after the operation, and make use of it at the
few call places.
Gcc 10.2 implements outline atomics on aarch64. The replace all inline
atomic ops with a function call that checks if the machine supports LSE
atomics. This comes with a small cost but allows modern machines to scale
much better than with the old LL/SC ones even when built for full 8.0
compatibility.
This patch enables the use of the __atomic_compare_exchange() builtin
for the double-word CAS when detected as available instead of using the
hand-written LL/SC version. The extra cost is negligible because we do
very few DWCAS operations (essentially FD migrations and shared pools)
so the cost is low but under high contention it can still be beneficial.
As expected no performance difference was measured in either direction
on 4-core machines with this change.
This could be backported to 2.3 if it was shown that FD migrations were
representing a significant source of contention, but for now it does
not appear to be needed.
Slightly reorder the status flags to better match their order in the
"state" field, and also decode the "shut" state which is particularly
useful and already part of this field.
There is a function called fd_write_frag_line() that's essentially used
by loggers and that is used to write an atomic message line over a file
descriptor using writev(). However a lock is required around the writev()
call to prevent messages from multiple threads from being interleaved.
Till now a SPIN_TRYLOCK was used on a dedicated lock that was common to
all FDs. This is quite not pretty as if there are multiple output pipes
to collect logs, there will be quite some contention. Now that there
are empty flags left in the FD state and that we can finally use atomic
ops on them, let's add a flag to indicate the FD is locked for exclusive
access by a syscall. At least the locking will now be on an FD basis and
not the whole process, so we can remove the log_lock.
No need to keep this flag apart any more, let's merge it into the global
state. The bit was not cleared in fd_insert() because the only user is
the function used to create and atomically send a log message to a pipe
FD, which never registers the fd. Here we clear it nevertheless for the
sake of clarity.
Note that with an extra cleaning pass we could have a bit number
here and simply use a BTS to test and set it.
No need to keep this flag apart any more, let's merge it into the global
state. The CLI's output state was extended to 6 digits and the linger/cloned
flags moved inside the parenthesis.
For a long time we've had fdtab[].ev and fdtab[].state which contain two
arbitrary sets of information, one is mostly the configuration plus some
shutdown reports and the other one is the latest polling status report
which also contains some sticky error and shutdown reports.
These ones used to be stored into distinct chars, complicating certain
operations and not even allowing to clearly see concurrent accesses (e.g.
fd_delete_orphan() would set the state to zero while fd_insert() would
only set the event to zero).
This patch creates a single uint with the two sets in it, still delimited
at the byte level for better readability. The original FD_EV_* values
remained at the lowest bit levels as they are also known by their bit
value. The next step will consist in merging the remaining bits into it.
The whole bits are now cleared both in fd_insert() and _fd_delete_orphan()
because after a complete check, it is certain that in both cases these
functions are the only ones touching these areas. Indeed, for
_fd_delete_orphan(), the thread_mask has already been zeroed before a
poller can call fd_update_event() which would touch the state, so it
is certain that _fd_delete_orphan() is alone. Regarding fd_insert(),
only one thread will get an FD at any moment, and it as this FD has
already been released by _fd_delete_orphan() by definition it is certain
that previous users have definitely stopped touching it.
Strictly speaking there's no need for clearing the state again in
fd_insert() but it's cheap and will remove some doubts during some
troubleshooting sessions.
In preparation of merging FD_POLL* and FD_EV*, this only changes the
value of FD_POLL_* to use bits 8-15 (the second byte). The size of the
field has been temporarily extended to 32 bits already, as well as
the temporary variables that carry the new composite value inside
fd_update_events(). The resulting fdtab entry becomes temporarily
unaligned. All places making access to .ev or FD_POLL_* were carefully
inspected to make sure they were safe regarding this change. Only one
temporary update was needed for the "show fd" code. The code was only
slightly inflated at this step.
The former was not used and the second was used only as a positive mask
of the flags to keep instead of having the flags that are updated. Both
were removed in favor of a new FD_POLL_UPDT_MASK that only mentions the
updated flags. This will ease merging of state and ev later.
The regression was introduced by commit previous commit 94aab06:
MEDIUM: log: support tcp or stream addresses on log lines.
This previous patch tries to retrieve the used protocol parsing
the address using the str2sa_range function but forgets that
the raw file descriptor adresses don't specify a protocol
and str2sa_range probes an error.
This patch re-work the str2sa_range function to stop
probing error if an authorized RAW_FD address is parsed
whereas the caller request also a protocol.
It also modify the code of parse_logsrv to switch on stream
logservers only if a protocol was detected.
Willy Tarreau
Tim Duesterhus
Christopher Faulet
Emeric Brun
Miroslav Zagorac