Re: [PATCH net-next 1/1] hv_netvsc: Properly size the vrss queues

[David Miller]

From: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
Date: Tue, 26 May 2015 16:21:09 -0700

> The current algorithm for deciding on the number of VRSS channels is
> not optimal since we open up the min of number of CPUs online and the
> number of VRSS channels the host is offering. So on a 32 VCPU guest
> we could potentially open 32 VRSS subchannels. Experimentation has
> shown that it is best to limit the number of VRSS channels to the number
> of CPUs within a NUMA node. As part of this work introduce a module
> parameter to control the number of sub-channels we would open up as well.
> Here is the new algorithm for deciding on the number of sub-channels we
> would open up:
>         1) Pick the minimum of what the host is offering and what the driver
>            in the guest is specifying via the module parameter.
>         2) Pick the minimum of (1) and the numbers of CPUs in the NUMA
>            node the primary channel is bound to.
> 
> Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>

No new module parameters, sorry.

You will have to make it such that this can be changed at run time,
and use a generic run-time mechanism to configure this value that any
driver can use.

I will not accept: "this is not possible" or "this is too hard" as a
reason why you have to use a module parameter.

Settings that cannot be set at run time are painful for people who run
large scale operations where resetting entire systems to change a
setting is completely and utterly impractical.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/