This will be used to detect and fix incorrect setups which report
the same cluster ID for multiple L3 instances.
The arrangement of functions in this file is becoming a real problem.
Maybe we should move all this to cpu_topo for example, and better
distinguish OS-specific and generic code.
Once we've kept only the CPUs we want, the next step will be to form
groups and these ones are based on locality. Thus we'll have to sort by
locality. For now the locality is only inferred by the index. No grouping
is made at this point. For this we add the "cpu_reorder_by_locality"
function with a locality-based comparison function.
CPU selection will be performed by sorting CPUs according to
various criteria. For dumps however, that's really not convenient
and we'll need to reorder the CPUs according to their index only.
This is what the new function cpu_reorder_by_index() does. It's
called in thread_detect_count() before dumping the CPU topology.
A number of entries under /cpu/cpu%d only exist on certain kernel
versions, certain archs and/or with certain modules loaded. It's
pointless to insist on trying to read them all for all CPUs when
we've already verified they do not exist. Thus let's use stat()
the first time prior to checking some of them, and only try to
access them when they really exist. This almost completely
eliminates the large number of ENOENT that was visible in strace
during startup.
Cpufreq alone isn't a good metric on heterogenous CPUs because efficient
cores can reach almost as high frequencies as performant ones. Tests have
shown that majoring performance cores by 50% gives a pretty accurate
estimate of the performance to expect on modern CPUs, and that counting
+33% per extra SMT thread is reasonable as well. We don't have the info
about the core's quality, but using the presence of SMT is a reasonable
approach in this case, given that efficiency cores will not use it.
As an example, using one thread of each of the 8 P-cores of an intel
i9-14900k gives 395k rps for a corrected total capacity of 69.3k, using
the 16 E-cores gives 40.5k for a total capacity of 70.4k, and using both
threads of 6 P-cores gives 41.1k for a total capacity of 69.6k. Thus the
3 same scores deliver the same performance in various combinations.
The acpi_cppc method was found to take about 5ms per CPU on a 64-core
EPYC system, which is plain unacceptable as it delays the boot by half
a second. Let's use the less accurate cpufreq first, which should be
sufficient anyway since many systems do not have acpi_cppc. We'll only
fall back to acpi_cppc for systems without cpufreq. If it were to be
an issue over time, we could also automatically consider that all
threads of the same core or even of the same cluster run at the same
speed (when a cluster is known to be accurate).
When cpu_capacity is not present, let's try to check acpi_cppc's
nominal_perf which is similar and commonly found on servers, then
scaling_max_freq (though that last one may vary a bit between CPUs
depending on die quality). That variation is not a problem since
we can absorb a ~5% variation without issue.
It was verified on an i9-14900 featuring 5.7-P, 6.0-P and 4.4-E GHz
that P-cores were not reordered and that E cores were placed last.
It was also OK on a W3-2345 with 4.3 to 4.5GHz.
It's becoming difficult to see which CPUs are going to be kept/dropped.
Let's just skip all offline CPUs, and indicate "keep" in front of those
that are going to be used, and "----" in front of the excluded ones. It
is way more readable this way.
Also let's just drop the array entry number, since it's always the same
as the CPU number and is only an internal representation anyway.
Let's reimplement automatic binding to the first NUMA node when thread
count is not forced. It's the same thing as is already done in
check_config_validity() except that this time it's based on the
collected CPU information. The threads are automatically counted
and CPUs from non-first node(s) are evicted.
If no cpu-map is done and no cpu-policy could be enforced, we still need
to count the number of usable CPUs, assign them to all threads and set
the nbthread value accordingly.
This already handles the part that was done in check_config_validity()
via thread_cpus_enabled_at_boot.
By mutually refining the thread count and group count, we can try
to detect the most suitable setup for the current machine. Taskset
is implicitly handled correctly. tgroups automatically adapt to the
configured number of threads. cpu-map manages to limit tgroups to
the smallest supported value.
The thread-limit is enforced. Just like in cfgparse, if the thread
count was forced to a higher value, it's reduced and a warning is
emitted. But if it was not set, the thr_max value is bound to this
limit so that further calculations respect it.
We continue to default to the max number of available threads and 1
tgroup by default, with the limit. This normally allows to get rid
of that test in check_config_validity().
For now it's limited, it only supports "reset" to ask that any previous
"taskset" be ignored. The goal will be to later add more actions that
allow to symbolically define sets of cpus to bind to or to drop. This
also clears the cpu_mask_forced variable that is used to detect
that a taskset had been used.
During development, everything related to CPU binding and the CPU topology
is debugged using state dumps at various places, but it does make sense to
have a real command line option so that this remains usable in production
to help users figure why some CPUs are not used by default. Let's add
"-dc" for this. Since the list of global.tune.options values is almost
full and does not 100% match this option, let's add a new "tune.debug"
field for this.
For now the function refrains from detecting the CPU topology when a
restrictive taskset or cpu-map was already performed on the process,
and it's documented as such, the reason being that until we're able
to automatically create groups, better not change user settings. But
we'll need to be able to detect bound CPUs and to process them as
desired by the user, so we now need to move that detection into the
function itself. It changes nothing to the logic, just gives more
freedom to the function.
The function is not convenient because it doesn't allow us to undo the
startup changes, and depending on where it's being used, we don't know
whether the values read have already been altered (this is not the case
right now but it's going to evolve).
Let's just compute the status during cpu_detect_usable() and set a
variable accordingly. This way we'll always read the init value, and
if needed we can even afford to reset it. Also, placing it in cpu_topo.c
limits cross-file dependencies (e.g. threads without affinity etc).
With this patch we're also NUMA node IDs to each CPU when the info is
found. The code is highly inspired from the one in commit f5d48f8b3
("MEDIUM: cfgparse: numa detect topology on FreeBSD."), the difference
being that we're just setting the value in ha_cpu_topo[].
With this patch we're also assigning NUMA node IDs to each CPU when one
is found. The code is highly inspired from the one in commit b56a7c89a
("MEDIUM: cfgparse: detect numa and set affinity if needed") that already
did the job, except that it could be simplified since we're just collecting
info to fill the ha_cpu_topo[] array.
The sibling ID was not reported because it's not directly accessible
but we don't care, what matters is that we assign numbers to all the
threads we find using the same CPU so that some strategies permit to
allocate one thread at a time if we want to use few threads with max
performance.
This uses the publicly available information from /sys to figure the cache
and package arrangements between logical CPUs and fill ha_cpu_topo[], as
well as their SMT capabilities and relative capacity for those which expose
this. The functions clearly have to be OS-specific.
When possible, the offline CPUs are detected at boot and their OFFLINE
flag is set in the ha_cpu_topo[] array. When the detection is not
possible (e.g. not linux, /sys not mounted etc), we just mark none of
them as being offline, as we don't want to infer wrong info that could
hinder automatic CPU placement detection. When valid, we take this
opportunity for refining cpu_topo_lastcpu so that we don't need to
manipulate CPUs beyond this value.
On FreeBSD we can detect online CPUs at least by doing the bitwise-OR of
the CPUs of all domains, so we're using this and adding this detection
to ha_cpuset_detect_online(). If we find simpler later, we can always
rework it, but it's reasonably inexpensive since we only check existing
domains.
This adds a generic function ha_cpuset_detect_online() which for now
only supports linux via /sys. It fills a cpuset with the list of online
CPUs that were detected (or returns a failure).
The cpuset files are normally used only for cpu manipulations. It happens
that the initial CPU binding detection was initially placed there since
there was no better place, but in practice, being OS-specific, it should
really be in cpu-topo. This simplifies cpuset which doesn't need to know
about the OS anymore.
Now before trying to resolve the thread assignment to groups, we detect
which CPUs are not bound at boot so that we can mark them with
HA_CPU_F_EXCLUDED. This will be useful to better know on which CPUs we
can count later. Note that we purposely ignore cpu-map here as we
don't know how threads and groups will map to cpu-map entries, hence
which CPUs will really be used.
It's important to proceed this way so that when we have no info we
assume they're all available.
The new function cpu_dump_topology() will centralize most debugging
calls, and it can make efforts of not dumping some possibly irrelevant
fields (e.g. non-existing cache levels).
We don't want to constantly deal with as many CPUs as a cpuset can hold,
so let's first try to trim the value to what the system claims to support
via _SC_NPROCESSORS_CONF. It is obviously still subject to the limit of
the cpuset size though. The value is stored globally so that we can
reuse it elsewhere after initialization.
This structure will be used to store information about each CPU's
topology (package ID, L3 cache ID, NUMA node ID etc). This will be used
in conjunction with CPU affinity setting to try to perform a mostly
optimal binding between threads and CPU numbers by default. Since it
was noticed during tests that absolutely none of the many machines
tested reports different die numbers, the die_id is not stored.
Also, it was found along experiments that the cluster ID will be used
a lot, half of the time as a node-local identifier, and half of the
time as a global identifier. So let's store the two versions at once
(cl_gid, cl_lid).
Some flags are added to indicate causes of exclusion (offline, excluded
at boot, excluded by rules, ignored by policy).
let's just clean up the thread_cpus_enabled() code a little bit
by removing the OS-specific code and rely on ha_cpuset_detect_bound()
instead. On macos we continue to use sysconf() for now.
Negative IDs are very convenient to mean "not set", so let's just make
the cpuset API robust against this, especially with ha_cpuset_isset()
so that we don't have to manually add this check everywhere when a
value is not known.
Lots of collected data and observations aggregated into a single commit
so as not to lose them. Some parts below come from several commit
messages and are incremental.
Add captures and analysis of intel 14900 where it's not easy to draw
the line between the desired P and E cores.
The 14900 raises some questions (imagine a dual-die variant in multi-socket).
That's the start of an algorithmic distribution of performance cores into
thread groups.
cpu-map currently conflicts a lot with the choices after auto-detection
but it doesn't have to. The problem is the inability to configure the
threads for the whole process like taskset does. By offering this ability
we can also start to designate groups of CPUs symbolically (package, die,
ccx, cores, smt).
It can also be useful to exploit the info from cpuinfo that is not
available in /sys, such as the model number. At least on arm, higher
numbers indicate bigger cores and can be useful to distinguish cores
inside a cluster. It will not indicate big vs medium ones of the same
type (e.g. a78 3.0 vs 2.4 GHz) but can still be effective at identifying
the efficient ones.
In short, infos such as cluster ID not always reliable, and are
local to the package. die_id as well. die number is not reported
here but should definitely be used, as a higher priority than L3.
We're still missing a discriminant between the l3 and cluster number
in order to address heterogenous CPUs (e.g. intel 14900), though in
terms of locality that's currently done correctly.
CPU selection is also a full topic, and some thoughts were noted
regarding sorting by perf vs locality so as never to mix inter-
socket CPUs due to sorting.
The proposed cpu-selection cannot work as-is, because it acts both on
restriction and preference, and these two are not actions but a sequence.
First restrictions must be enforced, and second the remaining CPUs are
sorted according to the preferred criterion, and a number of threads are
selected.
Currently we refine the OS-exposed cluster number but it's not correct
as we can end up with something poorly numbered. We need to respect the
LLC in any case so let's explain the approach.
This is also needed in order to make the requested number of CPUs
appear. For now we don't reroute to the original sysconf() call so
we return -1,EINVAL for all other info.
A build warning is emitted with gcc-4.8 in tools.c since commit
e920d73f59 ("MINOR: tools: improve symbol resolution without dl_addr")
because the compiler doesn't see that <size> is necessarily initialized.
Let's just preset it.
This adds run_poll_loop, run_tasks_from_lists, process_runnable_tasks,
ha_dump_backtrace and cli_io_handler which are fairly common in
backtraces. This will be less relative symbols when dladdr is not
usable.
Let's have a macro that declares both the symbol and its name, it will
avoid the risk of introducing typos, and encourages adding more when
needed. The macro also takes an optional second argument to permit an
inline declaration of an extern symbol.
When dl_addr is not usable or fails, better fall back to the closest
symbol among the known ones instead of providing everything relative
to main. Most often, the location of the function will give some hints
about what it can be. Thus now we can emit fct+0xXXX in addition to
main+0xXXX or main-0xXXX. We keep a margin of +256kB maximum after a
function for a match, which is around the maximum size met in an object
file, otherwise it becomes pointless again.
Performing a diff on stats output before vs after commit 66152526
("MEDIUM: stats: convert counters to new column definition") revealed
that some metrics were not properly ported to to the new API. Namely,
"lbtot", "cli_abrt" and "srv_abrt" are now exposed on frontend and
listeners while it was not the case before.
Also, "hrsp_other" is exposed even when "mode http" wasn't set on the
proxy.
In this patch we restore original behavior by fixing the capabilities
and hide settings.
As this could be considered as a minor regression (looking at the commit
message it doesn't seem intended), better tag this as a bug. It should be
backported in 3.0 with 66152526.
This is a complementary patch to cf913c2f9 ("DOC: management: rename show
stats domain cli "dns" to "resolvers"). The doc still refered to the
legacy "dns" domain filter for stat command. Let's rename those occurences
to "resolvers".
It may be backported to all stable versions.
Since commit 8de8ed4f48 ("MEDIUM: connections: Allow taking over
connections from other tgroups.") we got this partially absurd
build warning when disabling threads:
src/backend.c: In function 'conn_backend_get':
src/backend.c:1371:27: warning: array subscript [0, 0] is outside array bounds of 'struct tgroup_info[1]' [-Warray-bounds]
The reason is that gcc sees that curtgid is not equal to tgid which is
defined as 1 in this case, thus it figures that tgroup_info[curtgid-1]
will be anything but zero and that doesn't fit. It is ridiculous as it
is a perfect case of dead code elimination which should not warrant a
warning. Nevertheless we know we don't need to do this when threads are
disabled and in this case there will not be more than 1 thread group, so
we can happily use that preliminary test to help the compiler eliminate
the dead condition and avoid spitting this warning.
No backport is needed.
The dladdr_lock that was added to avoid re-entering into dladdr is
conditioned by threads, but the way it's declared causes a build
warning if threads are disabled due to the insertion of a lone semi
colon in the variables block. Let's switch to __decl_thread_var()
for this.
This can be backported wherever commit eb41d768f9 ("MINOR: tools:
use only opportunistic symbols resolution") is backported. It relies
on these previous two commits:
bb4addabb7 ("MINOR: compiler: add a simple macro to concatenate resolved strings")
69ac4cd315 ("MINOR: compiler: add a new __decl_thread_var() macro to declare local variables")
__decl_thread() already exists but is more suited for struct members.
When using it in a variables block, it appends the final trailing
semi-colon which is a statement that ends the variable block. Better
clean this up and have one precisely for variable blocks. In this
case we can simply define an unused enum value that will consume the
semi-colon. That's what the new macro __decl_thread_var() does.
It's often useful to be able to concatenate strings after resolving
them (e.g. __FILE__, __LINE__ etc). Let's just have a CONCAT() macro
to do that, which calls _CONCAT() with the same arguments to make
sure the contents are resolved before being concatenated.
A bug was uncovered by the work on NUMA. It only triggers in the CI
with libmusl due to a race condition. What happens is that the call
to set_thread_cpu_affinity() is done very early in the polling loop,
and that it relies on ha_pthread[tid] instead of pthread_self(). The
problem is that ha_pthread[tid] is only set by the return from
pthread_create(), which might happen later depending on the number of
CPUs available to run the starting thread.
Let's just use pthread_self() here. ha_pthread[] is only used to send
signals between threads, there's no point in using it here.
This can be backported to 2.6.
Historically, log-forward proxy used to preserve host field from input
message as much as possible, and if syslog host wasn't provided
(rfc5424 '-' or bad rfc3164 or rfc5424 message) then "localhost" or "-"
would be used as host when outputting message using rfc3164 or rfc5424.
We change that behavior (which corresponds to "keep" host option), so that
log-forward now uses "fill" strategy as default: if the host is provided
in input message, it is preserved. However if it is missing and IP address
from sender is available, we use it.
