Daniel P. Berrangé <berrange@redhat.com> pointed out that the coroutine
pool size heuristic is very conservative. Instead of halving
max_map_count, he suggested reserving 5,000 mappings for non-coroutine
users based on observations of guests he has access to.
Fixes: 86a637e481 ("coroutine: cap per-thread local pool size")
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-id: 20240320181232.1464819-1-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The coroutine pool implementation can hit the Linux vm.max_map_count
limit, causing QEMU to abort with "failed to allocate memory for stack"
or "failed to set up stack guard page" during coroutine creation.
This happens because per-thread pools can grow to tens of thousands of
coroutines. Each coroutine causes 2 virtual memory areas to be created.
Eventually vm.max_map_count is reached and memory-related syscalls fail.
The per-thread pool sizes are non-uniform and depend on past coroutine
usage in each thread, so it's possible for one thread to have a large
pool while another thread's pool is empty.
Switch to a new coroutine pool implementation with a global pool that
grows to a maximum number of coroutines and per-thread local pools that
are capped at hardcoded small number of coroutines.
This approach does not leave large numbers of coroutines pooled in a
thread that may not use them again. In order to perform well it
amortizes the cost of global pool accesses by working in batches of
coroutines instead of individual coroutines.
The global pool is a list. Threads donate batches of coroutines to when
they have too many and take batches from when they have too few:
.-----------------------------------.
| Batch 1 | Batch 2 | Batch 3 | ... | global_pool
`-----------------------------------'
Each thread has up to 2 batches of coroutines:
.-------------------.
| Batch 1 | Batch 2 | per-thread local_pool (maximum 2 batches)
`-------------------'
The goal of this change is to reduce the excessive number of pooled
coroutines that cause QEMU to abort when vm.max_map_count is reached
without losing the performance of an adequately sized coroutine pool.
Here are virtio-blk disk I/O benchmark results:
RW BLKSIZE IODEPTH OLD NEW CHANGE
randread 4k 1 113725 117451 +3.3%
randread 4k 8 192968 198510 +2.9%
randread 4k 16 207138 209429 +1.1%
randread 4k 32 212399 215145 +1.3%
randread 4k 64 218319 221277 +1.4%
randread 128k 1 17587 17535 -0.3%
randread 128k 8 17614 17616 +0.0%
randread 128k 16 17608 17609 +0.0%
randread 128k 32 17552 17553 +0.0%
randread 128k 64 17484 17484 +0.0%
See files/{fio.sh,test.xml.j2} for the benchmark configuration:
https://gitlab.com/stefanha/virt-playbooks/-/tree/coroutine-pool-fix-sizing
Buglink: https://issues.redhat.com/browse/RHEL-28947
Reported-by: Sanjay Rao <srao@redhat.com>
Reported-by: Boaz Ben Shabat <bbenshab@redhat.com>
Reported-by: Joe Mario <jmario@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20240318183429.1039340-1-stefanha@redhat.com>
touch_all_pages() can return early, before creating threads. In this case,
however, it leaks the MemsetContext that it has allocated at the
beginning of the function.
Reported by Coverity as CID 1534922.
Fixes: 04accf43df ("oslib-posix: initialize backend memory objects in parallel", 2024-02-06)
Reviewed-by: Mark Kanda <mark.kanda@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
SocketAddress branch @fd is documented in enum SocketAddressType,
unlike the other branches. That's because the branch's type is String
from common.json.
Use a local copy of String, so we can put the documentation in the
usual place.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240205074709.3613229-14-armbru@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
make vm-build-freebsd fails with:
ld: error: undefined symbol: inotify_init1
>>> referenced by filemonitor-inotify.c:183 (../src/util/filemonitor-inotify.c:183)
>>> util_filemonitor-inotify.c.o:(qemu_file_monitor_new) in archive libqemuutil.a
On FreeBSD the inotify functions are defined in libinotify.so. Add it
to the dependencies.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20240206002344.12372-5-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
QEMU initializes preallocated backend memory as the objects are parsed from
the command line. This is not optimal in some cases (e.g. memory spanning
multiple NUMA nodes) because the memory objects are initialized in series.
Allow the initialization to occur in parallel (asynchronously). In order to
ensure optimal thread placement, asynchronous initialization requires prealloc
context threads to be in use.
Signed-off-by: Mark Kanda <mark.kanda@oracle.com>
Message-ID: <20240131165327.3154970-2-mark.kanda@oracle.com>
Tested-by: Mario Casquero <mcasquer@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
This commit was created with scripts/clean-includes:
./scripts/clean-includes --git misc net/af-xdp.c plugins/*.c audio/pwaudio.c util/userfaultfd.c
All .c should include qemu/osdep.h first. The script performs three
related cleanups:
* Ensure .c files include qemu/osdep.h first.
* Including it in a .h is redundant, since the .c already includes
it. Drop such inclusions.
* Likewise, including headers qemu/osdep.h includes is redundant.
Drop these, too.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Conversion of docs/devel/qapi-code-gen.txt to ReST left several
dangling references behind. Fix them to point to
docs/devel/qapi-code-gen.rst.
Fixes: f7aa076dbd (docs: convert qapi-code-gen.txt to ReST)
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240120095327.666239-4-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
These rather complex functions have never been used since they've been
introduced in 2012, so looks like they are not really useful for QEMU.
And since the static normalize_uri_path() function is also only used by
uri_resolve(), we can remove that function now, too.
Reviewed-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: "Daniel P. Berrangé" <berrange@redhat.com>
Message-ID: <20240123182247.432642-3-thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Coroutine may be pooled even after COROUTINE_TERMINATE if
CONFIG_COROUTINE_POOL is enabled and fake stack should be saved in
such a case to keep AddressSanitizerUseAfterReturn working. Even worse,
I'm seeing stack corruption without fake stack being saved.
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20240117-asan-v2-1-26f9e1ea6e72@daynix.com>
uintptr_t, or unsigned long which is equivalent on Linux I32LP64 systems,
is an unsigned type and there is no need to further cast to __u64 which is
another unsigned integer type; widening casts from unsigned integers
zero-extend the value.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The Big QEMU Lock (BQL) has many names and they are confusing. The
actual QemuMutex variable is called qemu_global_mutex but it's commonly
referred to as the BQL in discussions and some code comments. The
locking APIs, however, are called qemu_mutex_lock_iothread() and
qemu_mutex_unlock_iothread().
The "iothread" name is historic and comes from when the main thread was
split into into KVM vcpu threads and the "iothread" (now called the main
loop thread). I have contributed to the confusion myself by introducing
a separate --object iothread, a separate concept unrelated to the BQL.
The "iothread" name is no longer appropriate for the BQL. Rename the
locking APIs to:
- void bql_lock(void)
- void bql_unlock(void)
- bool bql_locked(void)
There are more APIs with "iothread" in their names. Subsequent patches
will rename them. There are also comments and documentation that will be
updated in later patches.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Fabiano Rosas <farosas@suse.de>
Acked-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Acked-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-id: 20240102153529.486531-2-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
aio_context_set_aio_params() doesn't use its undocumented
Error** argument. Remove it to simplify.
Note this removes a use of "unchecked Error**" in
iothread_set_aio_context_params().
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20231120171806.19361-1-philmd@linaro.org>
Stefan Hajnoczi
Paolo Bonzini
Steve SistareandPeter Xu
Markus Armbruster
Peter Maydell
Ilya LeoshkevichandThomas Huth
Mark KandaandDavid Hildenbrand
Akihiko OdakiandStefan Hajnoczi
Philippe Mathieu-Daudé
Natanael CopaandRichard Henderson
