These flags indicate whether the call is made to fill a bind or a server
line, or even just send/recv calls (like logs or dns). Some special cases
are made for outgoing FDs (e.g. pipes for logs) or socket FDs (e.g external
listeners), and there's a distinction between stream or dgram usage that's
expected to significantly help str2sa_range() proceed appropriately with
the input information. For now they are not used yet.
It's the receiver's FD that's inherited from the parent process, not
the listener's so the flag must move to the receiver so that appropriate
actions can be taken.
Some socket settings used to be retrieved via the listener and the
bind_conf. Now instead we use the receiver and its settings whenever
appropriate. This will simplify the removal of the dependency on the
listener.
The netns is common to all listeners/receivers and is used to bind the
listening socket so it must be in the receiver settings and not in the
listener. This removes some yet another set of unnecessary loops.
The interface is common to all listeners/receivers and is used to bind
the listening socket so it must be in the receiver settings and not in
the listener. This removes some unnecessary loops.
Now we don't limit ourselves to listeners found in proxies nor peers
anymore, we're instead scanning all known FDs for those marked with
".exported=1". Just doing so has significantly simplified the code,
and will later allow to yield while sending FDs if desired.
When it comes to retrieving a possible namespace name or interface
name, for now this is only performed on listeners since these are the
only ones carrying such info. Once this moves somewhere else, we'll
be able to also pass these info for UDP receivers for example, with
only tiny changes.
During a reload operation, we used to send listener options associated
with each passed file descriptor. These were passed as binary contents
for the size of the "options" field in the struct listener. This means
that any flag value change or field size change would be problematic,
the former failing to properly grab certain options, the latter possibly
causing permanent failures during this operation.
Since these two previous commits:
MINOR: reload: determine the foreing binding status from the socket
BUG/MINOR: reload: detect the OS's v6only status before choosing an old socket
we don't need this anymore as the values are determined from the file
descriptor itself.
Let's just turn the previous 32 bits to vestigal space, send them as
zeroes and ignore them on receipt. The only possible side effect is if
someone would want to roll back from a 2.3 to 2.2 or earlier, such options
might be ignored during this reload. But other forthcoming changes might
make this fail as well anyway so that's not a reason for keeping this
behavior.
The FD takeover operation might have certain impacts explaining
unexpected activities, so it's important to report such a counter
there. We thus count the number of times a thread has stolen an
FD from another thread.
DEBUG_FD was added by commit 38e8a1c in 2.2-dev, and "show fd" was
slightly modified to still allow to print orphaned/closed FDs if their
count is non-null. But bypassing the existing test made it possible
to dereference fdt.owner which can be null. Let's adjust the condition
to avoid this.
No backport is needed.
When DEBUG_FD is set at build time, we'll keep a counter of per-FD events
in the fdtab. This counter is reported in "show fd" even for closed FDs if
not zero. The purpose is to help spot situations where an apparently closed
FD continues to be reported in loops, or where some events are dismissed.
Fix the semicolon escaping which must be handled in the master CLI,
the commands were wrongly splitted and could be forwarded partially to
the target CLI.
The master CLI must not do the escaping since it forwards the commands
to another CLI. It should be able to split into words by taking care of
the escaping, but must not remove the forwarded backslashes.
This fix do the same thing as the previous patch applied to the
cli_parse_request() function, by taking care of the escaping during the
word split, but it also remove the part which was removing the
backslashes from the forwarded command.
It was not possible to escape spaces over the CLI, making impossible the
insertion of new ACL entries with spaces from the CLI.
This patch fixes the escaping of spaces over the CLI.
It is now possible to launch "add acl agents.acl My\ User\ Agent" over
the CLI.
Could be backported in all stable branches.
Should fix issue #400.
This one was confusingly called, I thought it was the cumulated number
of streams but it's the number of calls to process_stream(). Let's make
this clearer.
empty_rq and long_rq are per-loop so it makes sense to group them
together with the loop count. In addition since ctxsw and tasksw
apply in the context of these counters, let's move them as well.
More precisely the difference between wake_tasks and long_rq should
roughly correspond to the number of inter-task messages. Visually
it's much easier to spot ratios of wakeup causes now.
We have poll_drop, poll_dead and poll_skip which are confusingly named
like their poll_io and poll_exp counterparts except that they are not
per poll() call but per-fd. This patch renames them to poll_drop_fd(),
poll_dead_fd() and poll_skip_fd() for this reason.
The "show activity" output mentions a number of indicators to explain
wake up reasons but doesn't have the number of times poll() sees some
I/O. And given that multiple events can happen simultaneously, it's
not always possible to deduce this metric by subtracting.
This patch adds a new "poll_io" counter that allows one to see how
often poll() returns with at least one active FD. This should help
detect stuck events and measure various ratios of poll sub-metrics.
Since 2.1-dev2, with commit 305d5ab46 ("MAJOR: fd: Get rid of the fd cache.")
we don't have the fd_lock anymore and as such its acitvity counter is always
zero. Let's remove it from the struct and from "show activity" output, as
there are already plenty of indicators to look at.
The cache line comment in the struct activity was updated to reflect
reality as it looks like another one already got removed in the past.
Getting rid of this warning is cleaner solved using a 'fall through' comment,
because it clarifies intent to a human reader.
This patch adjust a few places that cause -Wimplicit-fallthrough to trigger:
- Fix typos in the comment.
- Remove redundant 'no break' that trips up gcc from comment.
- Move the comment out of the block when the 'case' is completely surrounded
by braces.
- Add comments where I could determine that the fall through was intentional.
Changes tested on
gcc (Debian 9.3.0-13) 9.3.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
using
make -j4 all TARGET=linux-glibc USE_OPENSSL=1 USE_LUA=1 USE_ZLIB=1 USE_PCRE2=1 USE_PCRE2_JIT=1 USE_GETADDRINFO=1
This patch fixes all the leftovers from the include cleanup campaign. There
were not that many (~400 entries in ~150 files) but it was definitely worth
doing it as it revealed a few duplicates.
Most of the files dealing with error reports have to include log.h in order
to access ha_alert(), ha_warning() etc. But while these functions don't
depend on anything, log.h depends on a lot of stuff because it deals with
log-formats and samples. As a result it's impossible not to embark long
dependencies when using ha_warning() or qfprintf().
This patch moves these low-level functions to errors.h, which already
defines the error codes used at the same places. About half of the users
of log.h could be adjusted, sometimes revealing other issues such as
missing tools.h. Interestingly the total preprocessed size shrunk by
4%.
There's no point splitting the file in two since only cfgparse uses the
types defined there. A few call places were updated and cleaned up. All
of them were in C files which register keywords.
There is nothing left in common/ now so this directory must not be used
anymore.
This one was not easy because it was embarking many includes with it,
which other files would automatically find. At least global.h, arg.h
and tools.h were identified. 93 total locations were identified, 8
additional includes had to be added.
In the rare files where it was possible to finalize the sorting of
includes by adjusting only one or two extra lines, it was done. But
all files would need to be rechecked and cleaned up now.
It was the last set of files in types/ and proto/ and these directories
must not be reused anymore.
extern struct dict server_name_dict was moved from the type file to the
main file. A handful of inlined functions were moved at the bottom of
the file. Call places were updated to use server-t.h when relevant, or
to simply drop the entry when not needed.
The files remained mostly unchanged since they were OK. However, half of
the users didn't need to include them, and about as many actually needed
to have it and used to find functions like srv_currently_usable() through
a long chain that broke when moving the file.
This one is particularly difficult to split because it provides all the
functions used to manipulate a proxy state and to retrieve names or IDs
for error reporting, and as such, it was included in 73 files (down to
68 after cleanup). It would deserve a small cleanup though the cut points
are not obvious at the moment given the number of structs involved in
the struct proxy itself.
The current state of the logging is a real mess. The main problem is
that almost all files include log.h just in order to have access to
the alert/warning functions like ha_alert() etc, and don't care about
logs. But log.h also deals with real logging as well as log-format and
depends on stream.h and various other things. As such it forces a few
heavy files like stream.h to be loaded early and to hide missing
dependencies depending where it's loaded. Among the missing ones is
syslog.h which was often automatically included resulting in no less
than 3 users missing it.
Among 76 users, only 5 could be removed, and probably 70 don't need the
full set of dependencies.
A good approach would consist in splitting that file in 3 parts:
- one for error output ("errors" ?).
- one for log_format processing
- and one for actual logging.
Almost no change except moving the cli_kw struct definition after the
defines. Almost all users had both types&proto included, which is not
surprizing since this code is old and it used to be the norm a decade
ago. These places were cleaned.
Just some minor reordering, and the usual cleanup of call places for
those which didn't need it. We don't include the whole tools.h into
stats-t anymore but just tools-t.h.
The type file was slightly tidied. The cli-specific APPCTX_CLI_ST1_* flag
definitions were moved to cli.h. The type file was adjusted to include
buf-t.h and not the huge buf.h. A few call places were fixed because they
did not need this include.
Initially it looked like this could have been placed into auth.h or
stats.h but it's not the case as it's what makes the link between them
and the HTTP layer. However the file needed to be split in two. Quite
a number of call places were dropped because these were mostly leftovers
from the early days where the stats and cli were packed together.
The cfg_peers external declaration was moved to the main file instead
of the type one. A few types were still missing from the proto, causing
warnings in the functions prototypes (proxy, stick_table).
All includes that were not absolutely necessary were removed because
checks.h happens to very often be part of dependency loops. A warning
was added about this in check-t.h. The fields, enums and structs were
a bit tidied because it's particularly tedious to find anything there.
It would make sense to split this in two or more files (at least
extract tcp-checks).
The file was renamed to the singular because it was one of the rare
exceptions to have an "s" appended to its name compared to the struct
name.
The TASK_IS_TASKLET() macro was moved to the proto file instead of the
type one. The proto part was a bit reordered to remove a number of ugly
forward declaration of static inline functions. About a tens of C and H
files had their dependency dropped since they were not using anything
from task.h.
global.h was one of the messiest files, it has accumulated tons of
implicit dependencies and declares many globals that make almost all
other file include it. It managed to silence a dependency loop between
server.h and proxy.h by being well placed to pre-define the required
structs, forcing struct proxy and struct server to be forward-declared
in a significant number of files.
It was split in to, one which is the global struct definition and the
few macros and flags, and the rest containing the functions prototypes.
The UNIX_MAX_PATH definition was moved to compat.h.
This one is particularly tricky to move because everyone uses it
and it depends on a lot of other types. For example it cannot include
arg-t.h and must absolutely only rely on forward declarations to avoid
dependency loops between vars -> sample_data -> arg. In order to address
this one, it would be nice to split the sample_data part out of sample.h.
It was moved as-is, except for extern declaration of pattern_reference.
A few C files used to include it but didn't need it anymore after having
been split apart so this was cleaned.
One function prototype makes reference to struct mworker_proc which was
not defined there but in global.h instead. This definition, along with
the PROC_O_* fields were moved to mworker-t.h instead.
A few includes were missing in each file. A definition of
struct polled_mask was moved to fd-t.h. The MAX_POLLERS macro was
moved to defaults.h
Stdio used to be silently inherited from whatever path but it's needed
for list_pollers() which takes a FILE* and which can thus not be
forward-declared.
And also rename standard.c to tools.c. The original split between
tools.h and standard.h dates from version 1.3-dev and was mostly an
accident. This patch moves the files back to what they were expected
to be, and takes care of not changing anything else. However this
time tools.h was split between functions and types, because it contains
a small number of commonly used macros and structures (e.g. name_desc)
which in turn cause the massive list of includes of tools.h to conflict
with the callers.
They remain the ugliest files of the whole project and definitely need
to be cleaned and split apart. A few types are defined there only for
functions provided there, and some parts are even OS-specific and should
move somewhere else, such as the symbol resolution code.
The protocol.h files are pretty low in the dependency and (sadly) used
by some files from common/. Almost nothing was changed except lifting a
few comments.
This moves types/activity.h to haproxy/activity-t.h and
proto/activity.h to haproxy/activity.h.
The macros defining the bit field values for the profiling variable
were moved to the type file to be more future-proof.
This is the beginning of the move and cleanup of memory.h. This first
step only extracts type definitions and basic macros that are needed
by the files which reference a pool. They're moved to pool-t.h (since
"pool" is more obvious than "memory" when looking for pool-related
stuff). 3 files which didn't need to include the whole memory.h were
updated.
types/freq_ctr.h was moved to haproxy/freq_ctr-t.h and proto/freq_ctr.h
was moved to haproxy/freq_ctr.h. Files were updated accordingly, no other
change was applied.
This one is included almost everywhere and used to rely on a few other
.h that are not needed (unistd, stdlib, standard.h). It could possibly
make sense to split it into multiple parts to distinguish operations
performed on timers and the internal time accounting, but at this point
it does not appear much important.
Half of the users of this include only need the type definitions and
not the manipulation macros nor the inline functions. Moves the various
types into mini-clist-t.h makes the files cleaner. The other one had all
its includes grouped at the top. A few files continued to reference it
without using it and were cleaned.
In addition it was about time that we'd rename that file, it's not
"mini" anymore and contains a bit more than just circular lists.
This one used to be stored into debug.h but the debug tools got larger
and require a lot of other includes, which can't use BUG_ON() anymore
because of this. It does not make sense and instead this macro should
be placed into the lower includes and given its omnipresence, the best
solution is to create a new bug.h with the few surrounding macros needed
to trigger bugs and place assertions anywhere.
Another benefit is that it won't be required to add include <debug.h>
anymore to use BUG_ON, it will automatically be covered by api.h. No
less than 32 occurrences were dropped.
The FSM_PRINTF macro was dropped since not used at all anymore (probably
since 1.6 or so).
All files that were including one of the following include files have
been updated to only include haproxy/api.h or haproxy/api-t.h once instead:
- common/config.h
- common/compat.h
- common/compiler.h
- common/defaults.h
- common/initcall.h
- common/tools.h
The choice is simple: if the file only requires type definitions, it includes
api-t.h, otherwise it includes the full api.h.
In addition, in these files, explicit includes for inttypes.h and limits.h
were dropped since these are now covered by api.h and api-t.h.
No other change was performed, given that this patch is large and
affects 201 files. At least one (tools.h) was already freestanding and
didn't get the new one added.
A few fields, including a generic list entry, were added to the CLI context
by commit 300decc8d9 ("MINOR: cli: extend the CLI context with a list and
two offsets"). It turns out that the list entry (l0) is solely used to
consult rings and that the generic ring_write() code is restricted to a
consumer on the CLI due to this, which was not the initial intent. Let's
make it a general purpose wait_entry field that is properly initialized
during appctx_init(). This will allow any applet to wait on a ring, not
just the CLI.
Since the fix 5fd3b28 ("BUG/MEDIUM: cli: _getsocks must send the peers
sockets") for bug #443. The code which sends the socket for the peers
and the proxies is duplicated. This patch move this code in a separated
function.
This bug prevents to reload HAProxy when you have both the seamless
reload (-x / expose-fd listeners) and the peers.
Indeed the _getsocks command does not send the FDs of the peers
listeners, so if no reuseport is possible during the bind, the new
process will fail to bind and exits.
With this feature, it is not possible to fallback on the SIGTTOU method
if we didn't receive all the sockets, because you can't close() the
sockets of the new process without closing those of the previous
process, they are the same.
Should fix bug #443.
Must be backported as far as 1.8.
When trying to start HAProxy with the master CLI and more than one
program in the configuration, it refuses to start with:
[ALERT] 013/132926 (1378) : parsing [cur--1:0] : proxy 'MASTER', another server named 'cur--1' was already defined at line 0, please use distinct names.
[ALERT] 013/132926 (1378) : Fatal errors found in configuration.
The problem is that haproxy tries to create a server for the MASTER
proxy but only the worker are supposed to be in the server list.
Fix issue #446.
Must be backported as far as 2.0.
We use it half times for the global_listener_queue and half times
for a proxy's queue and this requires the callers to take care of
these. Let's split it in two versions, the current one working only
on the global queue and another one dedicated to proxies for the
per-proxy queues. This cleans up quite a bit of code.
The io_release() callback of the cli_kw is supposed to be used to clean
what an io_handler() has made. It is called once the work in the IO
handler is finished, or when the connection was aborted by the client.
This patch fixes a bug where the io_release callback was called even
when the parse() callback failed. Which means that the io_release() could
called even if the io_handler() was not called.
Should be backported in every versions that have a cli_kw->release().
(as far as 1.7)
Some commands like the debug ones are not enabled by default but can be
useful on some production environments. In order to avoid the temptation
of using them incorrectly, let's introduce an "expert" mode for a CLI
connection, which allows some commands to appear and be used. It is
enabled by command "expert-mode on" which is not listed by default.
Instead of using the same type for regular linked lists and "autolocked"
linked lists, use a separate type, "struct mt_list", for the autolocked one,
and introduce a set of macros, similar to the LIST_* macros, with the
MT_ prefix.
When we use the same entry for both regular list and autolocked list, as
is done for the "list" field in struct connection, we know have to explicitely
cast it to struct mt_list when using MT_ macros.
Since commit 7ac0e35f2 in 1.9-dev1 ("MAJOR: fd: compute the new fd polling
state out of the fd lock") we've started to update the FD POLLED bit a
bit more aggressively. Lately with the removal of the FD cache, this bit
is always equal to the ACTIVE bit. There's no point continuing to watch
it and update it anymore, all it does is create confusion and complicate
the code. One interesting side effect is that it now becomes visible that
all fd_*_{send,recv}() operations systematically call updt_fd_polling(),
except fd_cant_recv()/fd_cant_send() which never saw it change.
Some CLI parsers are currently abusing the CLI context types such as
pointers to stuff longs into them by lack of room. But the context is
80 bytes while cli is only 48, thus there's some room left. This patch
adds a list element and two size_t usable as various offsets. The list
element is initialized.
There were 221 places where a status message or an error message were built
to be returned on the CLI. All of them were replaced to use cli_err(),
cli_msg(), cli_dynerr() or cli_dynmsg() depending on what was expected.
This removed a lot of duplicated code because most of the times, 4 lines
are replaced by a single, safer one.
Right now we used to have extremely inconsistent states to report output,
one is CLI_ST_PRINT which prints constant message cli->msg with the
assigned severity, and CLI_ST_PRINT_FREE which prints dynamically
allocated cli->err with severity LOG_ERR, and nothing in between,
eventhough it's useful to be able to report dynamically allocated
messages as well as constant error messages.
This patch adds two extra states, which are not particularly well named
given the constraints imposed by existing ones. One is CLI_ST_PRINT_ERR
which prints a constant error message. The other one is CLI_ST_PRINT_DYN
which prints a dynamically allocated message. By doing so we maintain
the compatibility with current code.
It is important to keep in mind that we cannot pre-initialize pointers
and automatically detect what message type it is based on the assigned
fields, because the CLI's context is in a union shared with all other
users, thus unused fields contain anything upon return. This is why we
have no choice but using 4 states. Keeping the two fields <msg> and
<err> remains useful because one is const and not the other one, and
this catches may copy-paste mistakes. It's just that <err> is pretty
confusing here, it should be renamed.
Now that the architecture was changed so that attempts to receive/send data
always come from the upper layers, instead of them only trying to do so when
the lower layer let them know they could try, we can finally get rid of the
fd cache. We don't really need it anymore, and removing it gives us a small
performance boost.
When forcing the outgoing address of a connection, till now we used to
allocate this outgoing connection and set the address into it, then set
SF_ADDR_SET. With connection reuse this causes a whole lot of issues and
difficulties in the code.
Thanks to the previous changes, it is now possible to store the target
address into the stream instead, and copy the address from the stream to
the connection when initializing the connection. assign_server_address()
does this and as a result SF_ADDR_SET now reflects the presence of the
target address in the stream, not in the connection. The http_proxy mode,
the peers and the master's CLI now use the same mechanism. For now the
existing connection code was not removed to limit the amount of tricky
changes, but the allocated connection is not used anymore.
This change also revealed a latent issue that we've been having around
option http_proxy : the address was set in the connection but neither the
SF_ADDR_SET nor the SF_ASSIGNED flags were set. It looks like the connection
could establish only due to the fact that it existed with a non-null
destination address.
When using a level lower than admin on the master CLI, a \n is output
before the response, this is caused by the response of the "operator" or
"user" that are sent before the actual command.
To fix this problem we introduce the flag APPCTX_CLI_ST1_NOLF which ask
a command response to not be followed by the final \n.
This patch made a special case with the command operator and user
followed by a - so they are not followed by \n.
This patch must be backported to 2.0 and 1.9.
Since commit 829bd471 ("MEDIUM: stream: rearrange the events to remove
the loop"), the pipelining in the master CLI does not work anymore.
Indeed when doing:
echo "@1 show info; @2 show info; @3 show info" | socat /tmp/haproxy.master -
the CLI will only show the response of the first command.
When debugging we can observe that the command is sent, but the client
closes the connection before receiving the response.
The problem is that the flag CF_READ_NULL is not cleared when we
reiniate the flags of the response and we rely on this flag to close.
Must be backported in 2.0
As reported in GH issue #109 and in discourse issue
https://discourse.haproxy.org/t/haproxy-returns-408-or-504-error-when-timeout-client-value-is-every-25d
the time parser doesn't error on overflows nor underflows. This is a
recurring problem which additionally has the bad taste of taking a long
time before hitting the user.
This patch makes parse_time_err() return special error codes for overflows
and underflows, and adds the control in the call places to report suitable
errors depending on the requested unit. In practice, underflows are almost
never returned as the parsing function takes care of rounding values up,
so this might possibly happen on 64-bit overflows returning exactly zero
after rounding though. It is not really possible to cut the patch into
pieces as it changes the function's API, hence all callers.
Tests were run on about every relevant part (cookie maxlife/maxidle,
server inter, stats timeout, timeout*, cli's set timeout command,
tcp-request/response inspect-delay).
Haproxy is designed to be able to continue to run even under very low
memory conditions. However this can sometimes have a serious impact on
performance that it hard to diagnose. Let's report counters of failed
pool and buffer allocations per thread in show activity.
Most of the time we find ourselves adding per-thread fields to observe
activity, so let's compute these on the fly and display them. Now the
output shows "field: total [ thr0 thr1 ... thrn ]".
The unused fd_del and fd_skip were being abused during debugging sessions
as general purpose event counters. With their removal, let's officially
have dedicated counters for such use cases. These counters are called
"ctr0".."ctr2" and are listed at the end when DEBUG_DEV is set.
We still have quite a number of build macros which are mapped 1:1 to a
USE_something setting in the makefile but which have a different name.
This patch cleans this up by renaming them to use the USE_something
one, allowing to clean up the makefile and make it more obvious when
reading the code what build option needs to be added.
The following renames were done :
ENABLE_POLL -> USE_POLL
ENABLE_EPOLL -> USE_EPOLL
ENABLE_KQUEUE -> USE_KQUEUE
ENABLE_EVPORTS -> USE_EVPORTS
TPROXY -> USE_TPROXY
NETFILTER -> USE_NETFILTER
NEED_CRYPT_H -> USE_CRYPT_H
CONFIG_HAP_CRYPT -> USE_LIBCRYPT
CONFIG_HAP_NS -> DUSE_NS
CONFIG_HAP_LINUX_SPLICE -> USE_LINUX_SPLICE
CONFIG_HAP_LINUX_TPROXY -> USE_LINUX_TPROXY
CONFIG_HAP_LINUX_VSYSCALL -> USE_LINUX_VSYSCALL
Both the config and gdb report thread IDs starting at 1, so better do the
same in "show activity" to limit confusion. We also display the full
permitted range.
This could be backported to 1.9 since it was present there.
It's always a pain to have to stuff lots of #ifdef USE_OPENSSL around
ssl headers, it even results in some of them appearing in a random order
and multiple times just to benefit form an existing ifdef block. Let's
make these headers safe for inclusion when USE_OPENSSL is not defined,
they now perform the test themselves and do nothing if USE_OPENSSL is
not defined. This allows to remove no less than 8 such ifdef blocks
and make include blocks more readable.
They were all check to comply with the advertised openssl version. Now
that libressl doesn't pretend to be a more recent openssl anymore, we
can simply rely on the regular openssl version tests without having to
deal with exceptions for libressl.
Most tests on OPENSSL_VERSION_NUMBER have become complex and break all
the time because this number is fake for some derivatives like LibreSSL.
This patch creates a new macro, HA_OPENSSL_VERSION_NUMBER, which will
carry the real openssl version defining the compatibility level, and
this version will be adjusted depending on the variants.
SSL_SESSION_get0_id_context is introduced in LibreSSL-2.7.0
async operations are not supported by LibreSSL
early data is not supported by LibreSSL
packet_length is removed from SSL struct in LibreSSL
It's not logical to report context switch rates per thread in show activity
because everything else is a counter and it's not even possible to compare
values. Let's only report counts. Further, this simplifies the scheduler's
code.
It's particularly useful to spot runaway tasks to see this. The context
switch rate covers all tasklet calls (tasks and I/O handlers) while the
task wakeups only covers tasks picked from the run queue to be executed.
High values there will indicate either an intense traffic or a bug that
mades a task go wild.
