On Wed, Jun 11, 2014 at 01:27:07PM -0500, Dave Chiluk wrote:
> On 06/11/2014 11:18 AM, Paul E. McKenney wrote:
> > On Wed, Jun 11, 2014 at 10:46:00AM -0500, David Chiluk wrote:
> >> Now think about what happens when a gateway goes down, the namespaces
> >> need to be migrated, or a new machine needs to be brought up to replace
> >> it. When we're talking about 3000 namespaces, the amount of time it
> >> takes simply to recreate the namespaces becomes very significant.
> >>
> >> The script is a stripped down example of what exactly is being done on
> >> the neutron gateway in order to create namespaces.
> >
> > Are the namespaces torn down and recreated one at a time, or is there some
> > syscall, ioctl(), or whatever that allows bulk tear down and recreating?
> >
> > Thanx, Paul
>
> In the normal running case, the namespaces are created one at a time, as
> new customers create a new set of VMs on the cloud.
>
> However, in the case of failover to a new neutron gateway the namespaces
> are created all at once using the ip command (more or less serially).
>
> As far as I know there is no syscall or ioctl that allows bulk tear down
> and recreation. if such a beast exists that might be helpful.
The solution might be to create such a beast. I might be able to shave
a bit of time off of this benchmark, but at the cost of significant
increases in RCU's CPU consumption. A bulk teardown/recreation API could
reduce the RCU grace-period overhead by several orders of magnitude by
having a single RCU grace period cover a few thousand changes.
This is why other bulk-change syscalls exist.
Just out of curiosity, what syscalls does the ip command use?
Thanx, Paul
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
