xemu/docs
Paolo Bonzini 0ceb849bd3 AioContext: speed up aio_notify
In many cases, the call to event_notifier_set in aio_notify is unnecessary.
In particular, if we are executing aio_dispatch, or if aio_poll is not
blocking, we know that we will soon get to the next loop iteration (if
necessary); the thread that hosts the AioContext's event loop does not
need any nudging.

The patch includes a Promela formal model that shows that this really
works and does not need any further complication such as generation
counts.  It needs a memory barrier though.

The generation counts are not needed because any change to
ctx->dispatching after the memory barrier is okay for aio_notify.
If it changes from zero to one, it is the right thing to skip
event_notifier_set.  If it changes from one to zero, the
event_notifier_set is unnecessary but harmless.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-07-09 15:50:11 +02:00
..
qmp qapi: Change back sector-count to sectors-count in quorum QAPI events. 2014-07-01 10:15:34 +02:00
specs vhost-user: typo fixups 2014-06-29 19:39:41 +03:00
aio_notify.promela AioContext: speed up aio_notify 2014-07-09 15:50:11 +02:00
atomics.txt add a header file for atomic operations 2013-07-04 17:42:49 +02:00
blkverify.txt blkverify: Add block driver for verifying I/O 2010-09-21 17:00:53 +02:00
bootindex.txt Typo, spelling and grammatical fixes 2013-04-12 14:33:20 +02:00
ccid.txt libcacard: improve documentation 2014-06-10 07:44:01 +02:00
ich9-ehci-uhci.cfg usb: update documentation 2011-07-08 11:25:56 +02:00
libcacard.txt libcacard: Spelling and grammar fixes in documentation 2012-03-08 15:22:11 +00:00
live-block-ops.txt docs: describe live block operations 2012-01-26 14:49:18 +01:00
memory.txt docs/memory.txt: Fix document on MMIO operations 2014-05-07 21:00:44 +04:00
migration.txt savevm: Remove all the unneeded version_minimum_id_old (rest) 2014-05-14 15:24:51 +02:00
multiseat.txt docs/multiseat.txt: add note about spice 2014-06-04 08:40:42 +02:00
q35-chipset.cfg q35: Add PCIe switch to example q35 configuration 2013-08-21 12:39:15 +03:00
qapi-code-gen.txt qapi script: clean up in scripts 2014-06-27 09:27:56 -04:00
qdev-device-use.txt docs: Fix qdev-device-use.txt typo in -chardev serial, path=COM<NUM> 2011-09-09 09:43:17 +01:00
qemupciserial.inf Docs: Introduce multiport serial support in qemupciserial.inf. 2014-03-12 10:33:23 +01:00
rdma.txt rdma: rename 'x-rdma' => 'rdma' 2014-02-25 14:30:28 +01:00
spice-port-fqdn.txt docs: add spice-port-fqdn.txt 2012-12-17 14:01:41 +01:00
tracing.txt trace: Multi-backend tracing 2014-06-09 15:43:40 +02:00
usb2.txt usb: update docs for bus name change 2013-04-03 11:39:43 +02:00
usb-storage.txt Fix typos and misspellings 2013-03-22 13:25:07 +01:00
virtio-balloon-stats.txt virtio-balloon: return empty data when no stats are available 2014-05-25 12:46:58 +03:00
vnc-ledstate-Pseudo-encoding.txt doc: document the Pseudo-encoding of LED state 2013-04-29 08:28:51 -05:00
writing-qmp-commands.txt qmp hmp: Consistently name Error * objects err, and not errp 2014-05-08 14:20:00 -04:00
xbzrle.txt Add XBZRLE documentation 2012-08-08 13:51:11 +02:00
xen-save-devices-state.txt Introduce "xen-save-devices-state" 2012-03-19 18:21:00 +00:00