'event-loop-base' provides basic property handling for all 'AioContext'
based event loops. So let's define a new 'MainLoopClass' that inherits
from it. This will permit tweaking the main loop's properties through
qapi as well as through the command line using the '-object' keyword[1].
Only one instance of 'MainLoopClass' might be created at any time.
'EventLoopBaseClass' learns a new callback, 'can_be_deleted()' so as to
mark 'MainLoop' as non-deletable.
[1] For example:
-object main-loop,id=main-loop,aio-max-batch=<value>
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-id: 20220425075723.20019-3-nsaenzju@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This reverts commit b1c0734905. (We
wanted to do so once the 7.1 tree opens, which has happened. The issue
reported in https://gitlab.com/qemu-project/qemu/-/issues/945 should be
fixed by the preceding patches.)
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220427114057.36651-4-hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
These assertions are very useful for developers to find bugs, and so
they have indeed pointed us towards bugs already. For users, it is not
so useful to find these bugs. We should probably not enable them in
releases until we are sufficiently certain that they will not fire
during normal operation, unless something is going seriously wrong.
For example, we have received a bug report that you cannot add an NBD
server on a BDS in an I/O thread with `-incoming defer`. I am sure this
is a real bug that needs investigation, but we do not really have that
time right now, so close to release, and so I would rather disable the
assertions to get time to investigate such reports.
(I am just putting the link as "buglink" below, not "closes", because
disabling the assertion will not fix the likely underlying bug.)
Buglink: https://gitlab.com/qemu-project/qemu/-/issues/945
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220329093545.52114-1-hreitz@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Righ now, IO_CODE and IO_OR_GS_CODE are nop, as there isn't
really a way to check that a function is only called in I/O.
On the other side, we can use qemu_in_main_thread() to check if
we are in the main loop.
The usage of macros makes easy to extend them in the future without
making changes in all callers. They will also visually help understanding
in which category each function is, without looking at the header.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-3-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
When invoked from the main loop, this function is the same
as qemu_mutex_iothread_locked, and returns true if the BQL is held.
When invoked from iothreads or tests, it returns true only
if the current AioContext is the Main Loop.
This essentially just extends qemu_mutex_iothread_locked to work
also in unit tests or other users like storage-daemon, that run
in the Main Loop but end up using the implementation in
stubs/iothread-lock.c.
Using qemu_mutex_iothread_locked in unit tests defaults to false
because they use the implementation in stubs/iothread-lock,
making all assertions added in next patches fail despite the
AioContext is still the main loop.
See the comment in the function header for more information.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-2-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
It can be difficult to debug issues with BHs in production environments.
Although BHs can usually be identified by looking up their ->cb()
function pointer, this requires debug information for the program. It is
also not possible to print human-readable diagnostics about BHs because
they have no identifier.
This patch adds a name to each BH. The name is not unique per instance
but differentiates between cb() functions, which is usually enough. It's
done by changing aio_bh_new() and friends to macros that stringify cb.
The next patch will use the name field when reporting leaked BHs.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210414200247.917496-2-stefanha@redhat.com>
qemu_add_child_watch is not called anywhere since commit 2bdb920ece
("slirp: simplify fork_exec()", 2019-01-14), remove it.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20200827175520.32355-1-sw@weilnetz.de>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
move the vcpu throttling functionality into its own module.
This functionality is not specific to any accelerator,
and it is used currently by migration to slow down guests to try to
have migrations converge, and by the cocoa MacOS UI to throttle speed.
cpu-throttle contains the controls to adjust and inspect throttle
settings, start (set) and stop vcpu throttling, and the throttling
function itself that is run periodically on vcpus to make them take a nap.
Execution of the throttling function on all vcpus is triggered by a timer,
registered at module initialization.
No functionality change.
Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Message-Id: <20200629093504.3228-3-cfontana@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Introduce a wrapper function to wait on condition for
the main loop mutex. This function atomically releases
the main loop mutex and causes the calling thread to
block on the condition. This wrapper is required because
qemu_global_mutex is a static variable.
Signed-off-by: Aravinda Prasad <arawinda.p@gmail.com>
Signed-off-by: Ganesh Goudar <ganeshgr@linux.ibm.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <20200130184423.20519-2-ganeshgr@linux.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Remove hard-coded dependency on slirp in main-loop, and use a "poll"
notifier instead. The notifier is registered per slirp instance.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
The BQL is acquired via qemu_mutex_lock_iothread(), which makes
the profiler assign the associated wait time (i.e. most of
BQL wait time) entirely to that function. This loses the original
call site information, which does not help diagnose BQL contention.
Fix it by tracking the callers explicitly.
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20180602085259.17853-1-stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Remove the useless is_external argument. Since the iohandler
AioContext is never used for block devices, aio_disable_external
is never called on it. This lets us remove stubs/iohandler.c.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Commit 49cf57281b (vl: delay thread initialization after daemonization)
makes the global mutex is taken after daemonization instead before
daemonization by qemu_init_main_loop().
Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Message-Id: <1480566640-27264-2-git-send-email-baiyaowei@cmss.chinamobile.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In practice the entry argument is always known at creation time, and
it is confusing that sometimes qemu_coroutine_enter is used with a
non-NULL argument to re-enter a coroutine (this happens in
block/sheepdog.c and tests/test-coroutine.c). So pass the opaque value
at creation time, for consistency with e.g. aio_bh_new.
Mostly done with the following semantic patch:
@ entry1 @
expression entry, arg, co;
@@
- co = qemu_coroutine_create(entry);
+ co = qemu_coroutine_create(entry, arg);
...
- qemu_coroutine_enter(co, arg);
+ qemu_coroutine_enter(co);
@ entry2 @
expression entry, arg;
identifier co;
@@
- Coroutine *co = qemu_coroutine_create(entry);
+ Coroutine *co = qemu_coroutine_create(entry, arg);
...
- qemu_coroutine_enter(co, arg);
+ qemu_coroutine_enter(co);
@ entry3 @
expression entry, arg;
@@
- qemu_coroutine_enter(qemu_coroutine_create(entry), arg);
+ qemu_coroutine_enter(qemu_coroutine_create(entry, arg));
@ reentry @
expression co;
@@
- qemu_coroutine_enter(co, NULL);
+ qemu_coroutine_enter(co);
except for the aforementioned few places where the semantic patch
stumbled (as expected) and for test_co_queue, which would otherwise
produce an uninitialized variable warning.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
iohandler.c shares the same interface with aio, but with duplicated
code. It's better to rebase iohandler, also because that aio is a
more friendly interface to multi-threads.
Create a global AioContext instance and let its GSource handle the
iohandler events.
Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <1441596538-4412-1-git-send-email-famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This function will be used to avoid recursive locking of the iothread lock
whenever address_space_rw/ld*/st* are called with the BQL held, which is
almost always the case.
Tracking whether the iothread is owned is very cheap (just use a TLS
variable) but requires some care because now the lock must always be
taken with qemu_mutex_lock_iothread(). Previously this wasn't the case.
Outside TCG mode this is not a problem. In TCG mode, we need to be
careful and avoid the "prod out of compiled code" step if already
in a VCPU thread. This is easily done with a check on current_cpu,
i.e. qemu_in_vcpu_thread().
Hopefully, multithreaded TCG will get rid of the whole logic to kick
VCPUs whenever an I/O event occurs!
Cc: Frederic Konrad <fred.konrad@greensocs.com>
Message-Id: <1434646046-27150-3-git-send-email-pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
All users are converted to qemu_set_fd_handler now, drop
qemu_set_fd_handler2 and IOHandlerRecord.fd_read_poll.
Signed-off-by: Fam Zheng <famz@redhat.com>
Message-id: 1433400324-7358-9-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
On a system with a low limit of open files the initialization
of the event notifier could fail and QEMU exits without printing any
error information to the user.
The problem can be easily reproduced by enforcing a low limit of open
files and start QEMU with enough I/O threads to hit this limit.
The same problem raises, without the creation of I/O threads, while
QEMU initializes the main event loop by enforcing an even lower limit of
open files.
This commit adds an error message on failure:
# qemu [...] -object iothread,id=iothread0 -object iothread,id=iothread1
qemu: Failed to initialize event notifier: Too many open files in system
Signed-off-by: Chrysostomos Nanakos <cnanakos@grnet.gr>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
It is very useful to get the main loop AioContext, which is a static
variable in main-loop.c.
I'm not sure whether qemu_get_aio_context() will be necessary in the
future once devices focus on using their own AioContext instead of the
main loop AioContext, but for now it allows us to refactor code to
support multiple AioContext while actually passing the main loop
AioContext.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Convert iohandler_select_fill() and iohandler_select_poll() to use
GPollFD instead of rfds/wfds/xfds.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-id: 1361356113-11049-7-git-send-email-stefanha@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Nicolas Saenz Julienne
Hanna Reitz
Philippe Mathieu-Daudé
Emanuele Giuseppe Esposito
Stefan Hajnoczi
Paolo Bonzini
Stefan Weil
Claudio Fontana
Aravinda Prasad
Marc-André Lureau
Emilio G. Cota
Peter Maydell
Yaowei Bai
Markus Armbruster
Fam Zheng
Chrysostomos Nanakos