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authorStefan Hajnoczi <stefanha@redhat.com>2020-05-11 19:36:30 +0100
committerStefan Hajnoczi <stefanha@redhat.com>2020-05-18 18:16:00 +0100
commitba607ca8bff4d2c2062902f8355657c865ac7c29 (patch)
treede002f3ab22e267501feb4b691e51c22662b1753
parentde137e44f75d9868f5b548638081850f6ac771f2 (diff)
downloadqemu-arm-ba607ca8bff4d2c2062902f8355657c865ac7c29.tar.gz
aio-posix: disable fdmon-io_uring when GSource is used
The glib event loop does not call fdmon_io_uring_wait() so fd handlers waiting to be submitted build up in the list. There is no benefit is using io_uring when the glib GSource is being used, so disable it instead of implementing a more complex fix. This fixes a memory leak where AioHandlers would build up and increasing amounts of CPU time were spent iterating them in aio_pending(). The symptom is that guests become slow when QEMU is built with io_uring support. Buglink: https://bugs.launchpad.net/qemu/+bug/1877716 Fixes: 73fd282e7b6dd4e4ea1c3bbb3d302c8db51e4ccf ("aio-posix: add io_uring fd monitoring implementation") Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Tested-by: Oleksandr Natalenko <oleksandr@redhat.com> Message-id: 20200511183630.279750-3-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-rw-r--r--include/block/aio.h3
-rw-r--r--util/aio-posix.c12
-rw-r--r--util/aio-win32.c4
-rw-r--r--util/async.c1
4 files changed, 20 insertions, 0 deletions
diff --git a/include/block/aio.h b/include/block/aio.h
index 62ed954344..b2f703fa3f 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -701,6 +701,9 @@ void aio_context_setup(AioContext *ctx);
*/
void aio_context_destroy(AioContext *ctx);
+/* Used internally, do not call outside AioContext code */
+void aio_context_use_g_source(AioContext *ctx);
+
/**
* aio_context_set_poll_params:
* @ctx: the aio context
diff --git a/util/aio-posix.c b/util/aio-posix.c
index 8af334ab19..1b2a3af65b 100644
--- a/util/aio-posix.c
+++ b/util/aio-posix.c
@@ -682,6 +682,18 @@ void aio_context_destroy(AioContext *ctx)
aio_free_deleted_handlers(ctx);
}
+void aio_context_use_g_source(AioContext *ctx)
+{
+ /*
+ * Disable io_uring when the glib main loop is used because it doesn't
+ * support mixed glib/aio_poll() usage. It relies on aio_poll() being
+ * called regularly so that changes to the monitored file descriptors are
+ * submitted, otherwise a list of pending fd handlers builds up.
+ */
+ fdmon_io_uring_destroy(ctx);
+ aio_free_deleted_handlers(ctx);
+}
+
void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
int64_t grow, int64_t shrink, Error **errp)
{
diff --git a/util/aio-win32.c b/util/aio-win32.c
index 729d533faf..953c56ab48 100644
--- a/util/aio-win32.c
+++ b/util/aio-win32.c
@@ -414,6 +414,10 @@ void aio_context_destroy(AioContext *ctx)
{
}
+void aio_context_use_g_source(AioContext *ctx)
+{
+}
+
void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
int64_t grow, int64_t shrink, Error **errp)
{
diff --git a/util/async.c b/util/async.c
index 3165a28f2f..1319eee3bc 100644
--- a/util/async.c
+++ b/util/async.c
@@ -362,6 +362,7 @@ static GSourceFuncs aio_source_funcs = {
GSource *aio_get_g_source(AioContext *ctx)
{
+ aio_context_use_g_source(ctx);
g_source_ref(&ctx->source);
return &ctx->source;
}