The following changes since commit 801f3db7564dcce8a37a70833c0abe40ec19f8ce:

Merge remote-tracking branch 'remotes/philmd/tags/kconfig-20210720' into staging (2021-07-20 19:30:28 +0100)

for you to fetch changes up to d7ddd0a1618a75b31dc308bb37365ce1da972154:

linux-aio: limit the batch size using `aio-max-batch` parameter (2021-07-21 13:47:50 +0100)

Stefano Garzarella (3):

iothread: generalize iothread_set_param/iothread_get_param

iothread: add aio-max-batch parameter

linux-aio: limit the batch size using `aio-max-batch` parameter

qapi/misc.json | 6 ++-

qapi/qom.json | 7 +++-

include/block/aio.h | 12 ++++++

include/sysemu/iothread.h | 3 ++

block/linux-aio.c | 9 ++++-

iothread.c | 82 ++++++++++++++++++++++++++++++++++-----

monitor/hmp-cmds.c | 2 +

util/aio-posix.c | 12 ++++++

util/aio-win32.c | 5 +++

util/async.c | 2 +

qemu-options.hx | 8 +++-

11 files changed, 134 insertions(+), 14 deletions(-)

The `aio-max-batch` parameter will be propagated to AIO engines

and it will be used to control the maximum number of queued requests.

When there are in queue a number of requests equal to `aio-max-batch`,

the engine invokes the system call to forward the requests to the kernel.

This parameter allows us to control the maximum batch size to reduce

the latency that requests might accumulate while queued in the AIO

engine queue.

If `aio-max-batch` is equal to 0 (default value), the AIO engine will

use its default maximum batch size value.

Message-id: 20210721094211.69853-3-sgarzare@redhat.com

qapi/misc.json | 6 ++++-

qapi/qom.json | 7 ++++-

include/block/aio.h | 12 +++++++++

include/sysemu/iothread.h | 3 +++

iothread.c | 55 +++++++++++++++++++++++++++++++++++----

monitor/hmp-cmds.c | 2 ++

util/aio-posix.c | 12 +++++++++

util/aio-win32.c | 5 ++++

util/async.c | 2 ++

qemu-options.hx | 8 ++++--

10 files changed, 103 insertions(+), 9 deletions(-)

*/

iothread_init_gcontext(iothread);

- aio_context_set_poll_params(iothread->ctx,

- iothread->poll_max_ns,

- iothread->poll_grow,

- iothread->poll_shrink,

- &local_error);

+ iothread_set_aio_context_params(iothread, &local_error);

if (local_error) {

error_propagate(errp, local_error);

aio_context_unref(iothread->ctx);

@@ -XXX,XX +XXX,XX @@ static PollParamInfo poll_grow_info = {

static PollParamInfo poll_shrink_info = {

+static PollParamInfo aio_max_batch_info = {

+ "aio-max-batch", offsetof(IOThread, aio_max_batch),

+};

static void iothread_get_param(Object *obj, Visitor *v,

UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);

@@ -XXX,XX +XXX,XX @@ static void iothread_class_init(ObjectClass *klass, void *class_data)

iothread_get_poll_param,

iothread_set_poll_param,

NULL, &poll_shrink_info);

+ object_class_property_add(klass, "aio-max-batch", "int",

+ iothread_get_aio_param,

+ iothread_set_aio_param,

+ NULL, &aio_max_batch_info);

}

static const TypeInfo iothread_info = {

@@ -XXX,XX +XXX,XX @@ static int query_one_iothread(Object *object, void *opaque)

info->poll_max_ns = iothread->poll_max_ns;

info->poll_grow = iothread->poll_grow;

info->poll_shrink = iothread->poll_shrink;

+ info->aio_max_batch = iothread->aio_max_batch;

QAPI_LIST_APPEND(*tail, info);

return 0;

diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c

index XXXXXXX..XXXXXXX 100644

--- a/monitor/hmp-cmds.c

+++ b/monitor/hmp-cmds.c

@@ -XXX,XX +XXX,XX @@ void hmp_info_iothreads(Monitor *mon, const QDict *qdict)

monitor_printf(mon, " poll-max-ns=%" PRId64 "\n", value->poll_max_ns);

monitor_printf(mon, " poll-grow=%" PRId64 "\n", value->poll_grow);

monitor_printf(mon, " poll-shrink=%" PRId64 "\n", value->poll_shrink);

+ monitor_printf(mon, " aio-max-batch=%" PRId64 "\n",

+ value->aio_max_batch);

}

qapi_free_IOThreadInfoList(info_list);

diff --git a/util/aio-posix.c b/util/aio-posix.c

index XXXXXXX..XXXXXXX 100644

--- a/util/aio-posix.c

+++ b/util/aio-posix.c

@@ -XXX,XX +XXX,XX @@ void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,

aio_notify(ctx);

}

+

+void aio_context_set_aio_params(AioContext *ctx, int64_t max_batch,

+ Error **errp)

+{

+ /*

+ * No thread synchronization here, it doesn't matter if an incorrect value

+ * is used once.

+ */

+ ctx->aio_max_batch = max_batch;

+

+ aio_notify(ctx);

+}

diff --git a/util/aio-win32.c b/util/aio-win32.c

index XXXXXXX..XXXXXXX 100644

--- a/util/aio-win32.c

+++ b/util/aio-win32.c

@@ -XXX,XX +XXX,XX @@ void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,

error_setg(errp, "AioContext polling is not implemented on Windows");

}

}

+

+void aio_context_set_aio_params(AioContext *ctx, int64_t max_batch,

+ Error **errp)

+{

+}

diff --git a/util/async.c b/util/async.c

index XXXXXXX..XXXXXXX 100644

--- a/util/async.c

+++ b/util/async.c

@@ -XXX,XX +XXX,XX @@ AioContext *aio_context_new(Error **errp)

ctx->poll_grow = 0;

ctx->poll_shrink = 0;

+ ctx->aio_max_batch = 0;

+

return ctx;

fail:

g_source_destroy(&ctx->source);

diff --git a/qemu-options.hx b/qemu-options.hx

index XXXXXXX..XXXXXXX 100644

--- a/qemu-options.hx

+++ b/qemu-options.hx

@@ -XXX,XX +XXX,XX @@ SRST

CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB

- ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink``

+ ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink,aio-max-batch=aio-max-batch``

Creates a dedicated event loop thread that devices can be

assigned to. This is known as an IOThread. By default device

emulation happens in vCPU threads or the main event loop thread.

@@ -XXX,XX +XXX,XX @@ SRST

the polling time when the algorithm detects it is spending too

long polling without encountering events.

- The polling parameters can be modified at run-time using the

+ The ``aio-max-batch`` parameter is the maximum number of requests

+ in a batch for the AIO engine, 0 means that the engine will use

+ its default.

+

+ The IOThread parameters can be modified at run-time using the

``qom-set`` command (where ``iothread1`` is the IOThread's

``id``):

Changes in preparation for next patches where we add a new

parameter not related to the poll mechanism.

Let's add two new generic functions (iothread_set_param and

iothread_get_param) that we use to set and get IOThread

parameters.

Message-id: 20210721094211.69853-2-sgarzare@redhat.com

iothread.c | 27 +++++++++++++++++++++++----

1 file changed, 23 insertions(+), 4 deletions(-)

@@ -XXX,XX +XXX,XX @@ static PollParamInfo poll_shrink_info = {

"poll-shrink", offsetof(IOThread, poll_shrink),

-static void iothread_get_poll_param(Object *obj, Visitor *v,

+static void iothread_get_param(Object *obj, Visitor *v,

@@ -XXX,XX +XXX,XX @@ static void iothread_get_poll_param(Object *obj, Visitor *v,

visit_type_int64(v, name, field, errp);

-static void iothread_set_poll_param(Object *obj, Visitor *v,

+static bool iothread_set_param(Object *obj, Visitor *v,

@@ -XXX,XX +XXX,XX @@ static void iothread_set_poll_param(Object *obj, Visitor *v,

int64_t value;

if (!visit_type_int64(v, name, &value, errp)) {

- return;

+ return false;