Comment 26 for bug 1717224

------- Comment From <email address hidden> 2017-11-10 14:39 EDT-------
(In reply to comment #31)
> Hi Scott,
> the howto is mixed for Desktop users, Server users and selective upgrades.
> For your case you only need the most simple case which would be:
>
> Essentially you want to:
>
> # Check - all other updates done (to clear the view)
> $ apt list --upgradable
> Listing... Done
>
> # Enable proposed for z on Server
> $ echo "deb http://ports.ubuntu.com/ubuntu-ports/ xenial-proposed main
> restricted universe multiverse" | sudo tee
> /etc/apt/sources.list.d/enable-proposed.list
> $ sudo apt update
> $ apt list --upgradable
> [...]
> linux-headers-generic/xenial-proposed 4.4.0.100.105 s390x [upgradable from:
> 4.4.0.98.103]
> linux-headers-virtual/xenial-proposed 4.4.0.100.105 s390x [upgradable from:
> 4.4.0.98.103]
> linux-image-virtual/xenial-proposed 4.4.0.100.105 s390x [upgradable from:
> 4.4.0.98.103]
>
> # Install just the kernels from proposed
> $ sudo apt install linux-generic
>
> No need to set apt prefs if you only do a selective install.
> If you'd do a global "sudo apt upgrade" you'd get all, but that is likely
> not what you want in your case. After you have done so you can just
> enable/disable the line in /etc/apt/sources.list.d/enable-proposed.list as
> needed.
>
> Hope that helps

Yes, your instructions were immensely useful, thanks for the explanation.

With the proposed fix applied, I am now able to start over 100 virtual guests, even with aio-max-nr set to 64K:

root@zm93k8:~# cat /proc/sys/fs/aio-max-nr
65535

root@zm93k8:/tmp# virsh list |grep running
86 zs93kag70041 running
87 zs93kag70042 running
88 zs93kag70055 running
89 zs93kag70056 running
90 zs93kag70057 running
91 zs93kag70058 running
92 zs93kag70059 running
93 zs93kag70060 running
94 zs93kag70061 running
95 zs93kag70062 running
96 zs93kag70063 running
97 zs93kag70064 running
98 zs93kag70065 running
99 zs93kag70066 running
100 zs93kag70067 running
101 zs93kag70068 running
102 zs93kag70069 running
103 zs93kag70070 running
104 zs93kag70071 running
105 zs93kag70072 running
106 zs93kag70073 running
107 zs93kag70074 running
108 zs93kag70075 running
109 zs93kag70077 running
110 zs93kag70078 running
111 zs93kag70079 running
112 zs93kag70080 running
113 zs93kag70081 running
114 zs93kag70082 running
115 zs93kag70083 running
116 zs93kag70084 running
117 zs93kag70085 running
118 zs93kag70086 running
119 zs93kag70087 running
120 zs93kag70088 running
121 zs93kag70089 running
122 zs93kag70090 running
123 zs93kag70091 running
124 zs93kag70092 running
125 zs93kag70093 running
126 zs93kag70094 running
127 zs93kag70095 running
128 zs93kag70096 running
129 zs93kag70097 running
130 zs93kag70098 running
131 zs93kag70099 running
132 zs93kag70100 running
133 zs93kag70101 running
134 zs93kag70102 running
135 zs93kag70103 running
136 zs93kag70104 running
137 zs93kag70105 running
138 zs93kag70106 running
139 zs93kag70107 running
140 zs93kag70108 running
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142 zs93kag70110 running
143 zs93kag70111 running
144 zs93kag70112 running
145 zs93kag70113 running
146 zs93kag70114 running
147 zs93kag70115 running
148 zs93kag70116 running
149 zs93kag70117 running
150 zs93kag70118 running
151 zs93kag70119 running
152 zs93kag70120 running
153 zs93kag70121 running
154 zs93kag70122 running
155 zs93kag70123 running
156 zs93kag70124 running
157 zs93kag70125 running
158 zs93kag70126 running
159 zs93kag70127 running
160 zs93kag70128 running
161 zs93kag70129 running
162 zs93kag70130 running
163 zs93kag70131 running
164 zs93kag70132 running
165 zs93kag70133 running
166 zs93kag70134 running
167 zs93kag70135 running
168 zs93kag70136 running
169 zs93kag70137 running
170 zs93kag70138 running
172 zs93kag70024 running
173 zs93kag70025 running
174 zs93kag70026 running
175 zs93kag70027 running
176 zs93kag70038 running
177 zs93kag70039 running
178 zs93kag70040 running
179 zs93kag70043 running
180 zs93kag70044 running
181 zs93kag70045 running
182 zs93kag70046 running
183 zs93kag70047 running
184 zs93kag70048 running
185 zs93kag70049 running
186 zs93kag70050 running
187 zs93kag70051 running
188 zs93kag70052 running
189 zs93kag70053 running
190 zs93kag70054 running
191 zs93kag70076 running
root@zm93k8:/tmp#

When will this fix be available to external customers? We will want to recommend it to our zKVM users. Thank you !