[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [RFC PATCH 1/3] xl: replace vcpu-set --ignore-host with --ignore-warn



On 07/19/2013 04:48 PM, Konrad Rzeszutek Wilk wrote:
When Xen 4.3 was released we had a discussion whether we should
allow the vcpu-set command to allow the user to set more than
physical CPUs for a guest. The author brought up:
  - Xend used to do it,
  - If a user wants to do it, let them do it,
  - The original author of the change did not realize the
    side-effect his patch caused this and had no intention of changing it.
  - The user can already boot a massively overcommitted guest by
    having a large 'vcpus=' value in the guest config and we allow
    that.

Since we were close to the release we added --ignore-host parameter
as a mechanism for a user to still set more vCPUs that the physical
machine as a stop-gate.

This patch removes said option and adds the --ignore-warn option.
By default the user is allowed to set as many vCPUs as they would like.
We will print out a warning if the value is higher than the physical
CPU count. The --ignore-warn will silence said warning.

I think this is a good change in general, but I don't think the name is quite right. You're not ignoring the warnings, you're turning them off. Maybe make the function argument "warn", and the option "--no-warn"?

+    host_cpu = libxl_get_max_cpus(ctx);
+    if (max_vcpus > host_cpu && !ignore_warn) {
+        fprintf(stderr, "WARNING: You are overcommmitting! You have %d" \
+                " physical CPUs and want %d vCPUs! Continuing, use" \
+                " --ignore-warn to silence this.\n", host_cpu, max_vcpus);
      }

This is relatively minor, but you might as well keep the same basic structure here, and only call libxl_get_max_cpus() if warn is set.

 -George


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel


 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.