qemu/block
Stefan Hajnoczi 84d61e5f36 virtio: use defer_call() in virtio_irqfd_notify()
virtio-blk and virtio-scsi invoke virtio_irqfd_notify() to send Used
Buffer Notifications from an IOThread. This involves an eventfd
write(2) syscall. Calling this repeatedly when completing multiple I/O
requests in a row is wasteful.

Use the defer_call() API to batch together virtio_irqfd_notify() calls
made during thread pool (aio=threads), Linux AIO (aio=native), and
io_uring (aio=io_uring) completion processing.

Behavior is unchanged for emulated devices that do not use
defer_call_begin()/defer_call_end() since defer_call() immediately
invokes the callback when called outside a
defer_call_begin()/defer_call_end() region.

fio rw=randread bs=4k iodepth=64 numjobs=8 IOPS increases by ~9% with a
single IOThread and 8 vCPUs. iodepth=1 decreases by ~1% but this could
be noise. Detailed performance data and configuration specifics are
available here:
https://gitlab.com/stefanha/virt-playbooks/-/tree/blk_io_plug-irqfd

This duplicates the BH that virtio-blk uses for batching. The next
commit will remove it.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230913200045.1024233-4-stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-10-31 15:42:14 +01:00
..
export block: Mark bdrv_first_blk() and bdrv_is_root_node() GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
monitor block: Mark bdrv_op_is_blocked() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
accounting.c block: add missed block_acct_setup with new block device init procedure 2022-09-30 18:42:34 +02:00
aio_task.c block/aio_task: assert max_busy_tasks is greater than 0 2021-10-05 18:56:41 +02:00
amend.c block: Mark BlockDriver callbacks for amend job GRAPH_RDLOCK 2023-05-10 14:16:54 +02:00
backup.c block: Mark bdrv_get_parent_name() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
blkdebug.c blkdebug: add missing coroutine_fn annotation 2023-04-25 13:17:28 +02:00
blkio.c util/defer-call: move defer_call() to util/ 2023-10-31 15:41:42 +01:00
blklogwrites.c block: Mark bdrv_unref_child() GRAPH_WRLOCK 2023-09-20 17:46:01 +02:00
blkreplay.c block: Mark bdrv_co_refresh_total_sectors() and callers GRAPH_RDLOCK 2023-02-23 19:49:33 +01:00
blkverify.c block: Mark bdrv_unref_child() GRAPH_WRLOCK 2023-09-20 17:46:01 +02:00
block-backend.c block: Mark bdrv_op_is_blocked() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
block-copy.c block: spelling fixes 2023-09-08 13:08:52 +03:00
block-gen.h block-coroutine-wrapper.py: support also basic return types 2022-12-15 16:07:43 +01:00
block-ram-registrar.c block: add BlockRAMRegistrar 2022-10-26 14:56:42 -04:00
bochs.c block: Mark bdrv_apply_auto_read_only() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
cloop.c block: Mark bdrv_apply_auto_read_only() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
commit.c block: Mark bdrv_op_is_blocked() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
copy-before-write.c block: convert more bdrv_is_allocated* and bdrv_block_status* calls to coroutine versions 2023-10-12 16:31:33 +02:00
copy-before-write.h block/copy-before-write.h: global state API + assertions 2022-03-04 18:18:25 +01:00
copy-on-read.c block: convert more bdrv_is_allocated* and bdrv_block_status* calls to coroutine versions 2023-10-12 16:31:33 +02:00
copy-on-read.h Clean up ill-advised or unusual header guards 2022-05-11 16:50:01 +02:00
coroutines.h nbd: Mark nbd_co_do_establish_connection() and callers GRAPH_RDLOCK 2023-05-10 14:16:53 +02:00
create.c block: Call .bdrv_co_create(_opts) unlocked 2023-05-19 19:12:12 +02:00
crypto.c block: Mark bdrv_amend_options() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
crypto.h nomaintainer: Fix Lesser GPL version number 2020-11-15 17:04:40 +01:00
curl.c block: Mark bdrv_apply_auto_read_only() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
dirty-bitmap.c block: Mark bdrv_*_dirty_bitmap() and callers GRAPH_RDLOCK 2023-02-23 19:49:32 +01:00
dmg-bz2.c Include qemu-common.h exactly where needed 2019-06-12 13:20:20 +02:00
dmg-lzfse.c block/dmg: Ignore C99 prototype declaration mismatch from <lzfse.h> 2023-03-30 15:03:36 +02:00
dmg.c block: Mark bdrv_apply_auto_read_only() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
dmg.h block/dmg: Declare a type definition for DMG uncompress function 2023-04-24 13:53:44 -04:00
file-posix.c Block patches 2023-09-21 09:05:10 -04:00
file-win32.c thread-pool: avoid passing the pool parameter every time 2023-04-25 13:17:28 +02:00
filter-compress.c block: remove has_variable_length from filters 2023-04-11 16:38:56 +02:00
gluster.c block: Mark bdrv_apply_auto_read_only() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
graph-lock.c block: Add assertion for bdrv_graph_wrlock() 2023-10-12 16:31:33 +02:00
io_uring.c virtio: use defer_call() in virtio_irqfd_notify() 2023-10-31 15:42:14 +01:00
io.c block: Mark bdrv_parent_cb_resize() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
iscsi-opts.c modules: add block module annotations 2021-07-09 18:20:27 +02:00
iscsi.c block: Mark bdrv_apply_auto_read_only() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
linux-aio.c virtio: use defer_call() in virtio_irqfd_notify() 2023-10-31 15:42:14 +01:00
meson.build util/defer-call: move defer_call() to util/ 2023-10-31 15:41:42 +01:00
mirror.c block: convert more bdrv_is_allocated* and bdrv_block_status* calls to coroutine versions 2023-10-12 16:31:33 +02:00
nbd.c block: Mark bdrv_apply_auto_read_only() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
nfs.c block: Mark bdrv_refresh_filename() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
null.c block: Convert bdrv_get_allocated_file_size() to co_wrapper 2023-02-01 16:52:32 +01:00
nvme.c util/defer-call: move defer_call() to util/ 2023-10-31 15:41:42 +01:00
parallels-ext.c include/block: Untangle inclusion loops 2023-01-20 07:24:28 +01:00
parallels.c migration: simplify blockers 2023-10-20 08:51:41 +02:00
parallels.h parallels: collect bitmap of used clusters at open 2023-09-21 08:47:34 +02:00
preallocate.c preallocate: Don't poll during permission updates 2023-09-20 17:46:00 +02:00
progress_meter.c coroutine: Clean up superfluous inclusion of qemu/lockable.h 2023-01-19 10:18:28 +01:00
qapi-sysemu.c block: Fix locking in media change monitor commands 2023-10-31 13:51:28 +01:00
qapi.c block: Mark bdrv_refresh_filename() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
qcow2-bitmap.c qcow2: Mark check_constraints_on_bitmap() GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
qcow2-cache.c qcow2: Mark qcow2_signal_corruption() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
qcow2-cluster.c qcow2: Mark qcow2_signal_corruption() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
qcow2-refcount.c qcow2: Mark qcow2_signal_corruption() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
qcow2-snapshot.c qcow2: mark various functions as coroutine_fn and GRAPH_RDLOCK 2023-04-25 13:17:28 +02:00
qcow2-threads.c thread-pool: avoid passing the pool parameter every time 2023-04-25 13:17:28 +02:00
qcow2.c qcow2: Mark qcow2_inactivate() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
qcow2.h qcow2: Mark qcow2_signal_corruption() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
qcow.c migration: simplify blockers 2023-10-20 08:51:41 +02:00
qed-check.c qed: mark more functions as coroutine_fns and GRAPH_RDLOCK 2023-06-28 09:46:20 +02:00
qed-cluster.c qed: protect table cache with CoMutex 2017-07-17 11:34:11 +08:00
qed-l2-cache.c osdep: Move memalign-related functions to their own header 2022-03-07 13:16:49 +00:00
qed-table.c block: use bdrv_co_debug_event in coroutine context 2023-06-28 09:46:34 +02:00
qed.c block: mark mixed functions that can suspend 2023-09-26 18:09:08 +02:00
qed.h block: Mark public read/write functions GRAPH_RDLOCK 2023-02-23 19:49:17 +01:00
quorum.c block: Mark bdrv_get_parent_name() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
raw-format.c block: Mark bdrv_refresh_filename() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
rbd.c block: Mark bdrv_apply_auto_read_only() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
replication.c block: Protect bs->children with graph_lock 2023-10-12 16:31:33 +02:00
reqlist.c block/reqlist: add reqlist_wait_all() 2022-03-07 09:33:30 +01:00
snapshot-access.c block: Make more BlockDriver definitions static 2023-09-08 17:03:09 +02:00
snapshot.c block: Mark bdrv_get_parent_name() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
ssh.c aio: remove aio_disable_external() API 2023-05-30 17:37:26 +02:00
stream.c block: convert more bdrv_is_allocated* and bdrv_block_status* calls to coroutine versions 2023-10-12 16:31:33 +02:00
throttle-groups.c block: mark mixed functions that can suspend 2023-09-26 18:09:08 +02:00
throttle.c block/throttle-groups: Use ThrottleDirection instread of bool is_write 2023-08-29 10:49:24 +02:00
trace-events nbd/client: Accept 64-bit block status chunks 2023-10-05 11:02:08 -05:00
trace.h trace: switch position of headers to what Meson requires 2020-08-21 06:18:24 -04:00
vdi.c migration: simplify blockers 2023-10-20 08:51:41 +02:00
vhdx-endian.c Include qemu-common.h exactly where needed 2019-06-12 13:20:20 +02:00
vhdx-log.c vhdx: mark more functions as coroutine_fns and GRAPH_RDLOCK 2023-06-28 09:46:30 +02:00
vhdx.c migration: simplify blockers 2023-10-20 08:51:41 +02:00
vhdx.h block: Mark bdrv_refresh_filename() and callers GRAPH_RDLOCK 2023-10-12 16:31:33 +02:00
vmdk.c migration: simplify blockers 2023-10-20 08:51:41 +02:00
vpc.c migration: simplify blockers 2023-10-20 08:51:41 +02:00
vvfat.c migration: simplify blockers 2023-10-20 08:51:41 +02:00
win32-aio.c aio: remove aio_disable_external() API 2023-05-30 17:37:26 +02:00
write-threshold.c include/block: Untangle inclusion loops 2023-01-20 07:24:28 +01:00