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[PATCH 1/3] file-posix: add `aio-max-batch` option
From: |
Stefano Garzarella |
Subject: |
[PATCH 1/3] file-posix: add `aio-max-batch` option |
Date: |
Thu, 23 Sep 2021 16:30:58 +0200 |
Commit d7ddd0a161 ("linux-aio: limit the batch size using
`aio-max-batch` parameter") added a way to limit the batch size
of Linux AIO backend for the entire AIO context.
The same AIO context can be shared by multiple devices, so
latency-sensitive devices may want to limit the batch size even
more to avoid increasing latency.
For this reason we add the `aio-max-batch` option to the file
backend, which will be used by the next commits to limit the size of
batches including requests generated by this device.
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
qapi/block-core.json | 5 +++++
block/file-posix.c | 9 +++++++++
2 files changed, 14 insertions(+)
diff --git a/qapi/block-core.json b/qapi/block-core.json
index c8ce1d9d5d..1a8ed325bc 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2851,6 +2851,10 @@
# for this device (default: none, forward the commands via SG_IO;
# since 2.11)
# @aio: AIO backend (default: threads) (since: 2.8)
+# @aio-max-batch: maximum number of requests in an AIO backend batch that
+# contains request from this block device. 0 means that the
+# AIO backend will handle it automatically.
+# (default:0, since 6.2)
# @locking: whether to enable file locking. If set to 'auto', only enable
# when Open File Descriptor (OFD) locking API is available
# (default: auto, since 2.10)
@@ -2879,6 +2883,7 @@
'*pr-manager': 'str',
'*locking': 'OnOffAuto',
'*aio': 'BlockdevAioOptions',
+ '*aio-max-batch': 'int',
'*drop-cache': {'type': 'bool',
'if': 'CONFIG_LINUX'},
'*x-check-cache-dropped': 'bool' },
diff --git a/block/file-posix.c b/block/file-posix.c
index d81e15efa4..da50e94034 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -150,6 +150,8 @@ typedef struct BDRVRawState {
uint64_t locked_perm;
uint64_t locked_shared_perm;
+ uint64_t aio_max_batch;
+
int perm_change_fd;
int perm_change_flags;
BDRVReopenState *reopen_state;
@@ -530,6 +532,11 @@ static QemuOptsList raw_runtime_opts = {
.type = QEMU_OPT_STRING,
.help = "host AIO implementation (threads, native, io_uring)",
},
+ {
+ .name = "aio-max-batch",
+ .type = QEMU_OPT_NUMBER,
+ .help = "AIO max batch size (0 = auto handled by AIO backend,
default: 0)",
+ },
{
.name = "locking",
.type = QEMU_OPT_STRING,
@@ -609,6 +616,8 @@ static int raw_open_common(BlockDriverState *bs, QDict
*options,
s->use_linux_io_uring = (aio == BLOCKDEV_AIO_OPTIONS_IO_URING);
#endif
+ s->aio_max_batch = qemu_opt_get_number(opts, "aio-max-batch", 0);
+
locking = qapi_enum_parse(&OnOffAuto_lookup,
qemu_opt_get(opts, "locking"),
ON_OFF_AUTO_AUTO, &local_err);
--
2.31.1