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From 06583ce33fab2976157461ac4503d6f8eeb59e75 Mon Sep 17 00:00:00 2001
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From: Hanna Reitz <hreitz@redhat.com>
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Date: Fri, 4 Feb 2022 12:10:12 +0100
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Subject: [PATCH 8/8] iotests/281: Let NBD connection yield in iothread
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RH-Author: Hanna Reitz <hreitz@redhat.com>
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RH-MergeRequest: 74: block/nbd: Handle AioContext changes
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RH-Commit: [6/6] 632b9ef5177a80d1c0c00121e1acc37272076d3e (hreitz/qemu-kvm-c-9-s)
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RH-Bugzilla: 2033626
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Acked-by: Eric Blake <eblake@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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Put an NBD block device into an I/O thread, and then read data from it,
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hoping that the NBD connection will yield during that read. When it
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does, the coroutine must be reentered in the block device's I/O thread,
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which will only happen if the NBD block driver attaches the connection's
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QIOChannel to the new AioContext. It did not do that after 4ddb5d2fde
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("block/nbd: drop connection_co") and prior to "block/nbd: Move s->ioc
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on AioContext change", which would cause an assertion failure.
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To improve our chances of yielding, the NBD server is throttled to
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reading 64 kB/s, and the NBD client reads 128 kB, so it should yield at
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some point.
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Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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Signed-off-by: Hanna Reitz <hreitz@redhat.com>
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Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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(cherry picked from commit 8cfbe929e8c26050f0a4580a1606a370a947d4ce)
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Signed-off-by: Hanna Reitz <hreitz@redhat.com>
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---
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tests/qemu-iotests/281 | 28 +++++++++++++++++++++++++---
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tests/qemu-iotests/281.out | 4 ++--
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2 files changed, 27 insertions(+), 5 deletions(-)
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diff --git a/tests/qemu-iotests/281 b/tests/qemu-iotests/281
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index 13c588be75..b2ead7f388 100755
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--- a/tests/qemu-iotests/281
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+++ b/tests/qemu-iotests/281
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@@ -253,8 +253,9 @@ class TestYieldingAndTimers(iotests.QMPTestCase):
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self.create_nbd_export()
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# Simple VM with an NBD block device connected to the NBD export
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- # provided by the QSD
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+ # provided by the QSD, and an (initially unused) iothread
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self.vm = iotests.VM()
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+ self.vm.add_object('iothread,id=iothr')
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self.vm.add_blockdev('nbd,node-name=nbd,server.type=unix,' +
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f'server.path={self.sock},export=exp,' +
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'reconnect-delay=1')
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@@ -293,19 +294,40 @@ class TestYieldingAndTimers(iotests.QMPTestCase):
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# thus not see the error, and so the test will pass.)
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time.sleep(2)
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+ def test_yield_in_iothread(self):
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+ # Move the NBD node to the I/O thread; the NBD block driver should
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+ # attach the connection's QIOChannel to that thread's AioContext, too
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+ result = self.vm.qmp('x-blockdev-set-iothread',
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+ node_name='nbd', iothread='iothr')
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+ self.assert_qmp(result, 'return', {})
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+
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+ # Do some I/O that will be throttled by the QSD, so that the network
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+ # connection hopefully will yield here. When it is resumed, it must
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+ # then be resumed in the I/O thread's AioContext.
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+ result = self.vm.qmp('human-monitor-command',
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+ command_line='qemu-io nbd "read 0 128K"')
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+ self.assert_qmp(result, 'return', '')
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+
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def create_nbd_export(self):
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assert self.qsd is None
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- # Simple NBD export of a null-co BDS
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+ # Export a throttled null-co BDS: Reads are throttled (max 64 kB/s),
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+ # writes are not.
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self.qsd = QemuStorageDaemon(
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+ '--object',
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+ 'throttle-group,id=thrgr,x-bps-read=65536,x-bps-read-max=65536',
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+
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'--blockdev',
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'null-co,node-name=null,read-zeroes=true',
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+ '--blockdev',
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+ 'throttle,node-name=thr,file=null,throttle-group=thrgr',
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+
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'--nbd-server',
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f'addr.type=unix,addr.path={self.sock}',
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'--export',
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- 'nbd,id=exp,node-name=null,name=exp,writable=true'
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+ 'nbd,id=exp,node-name=thr,name=exp,writable=true'
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)
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def stop_nbd_export(self):
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diff --git a/tests/qemu-iotests/281.out b/tests/qemu-iotests/281.out
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index 914e3737bd..3f8a935a08 100644
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--- a/tests/qemu-iotests/281.out
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+++ b/tests/qemu-iotests/281.out
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@@ -1,5 +1,5 @@
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-.....
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+......
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----------------------------------------------------------------------
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-Ran 5 tests
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+Ran 6 tests
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OK
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--
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2.27.0
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