Messages in this thread | | | Date | Mon, 25 Aug 2014 10:57:11 +0800 | From | Jason Wang <> | Subject | Re: [RFC 2/4] tuntap: Publish tuntap maximum number of queues as module_param |
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On 08/24/2014 07:14 PM, Michael S. Tsirkin wrote: > On Fri, Aug 22, 2014 at 07:52:22AM -0400, Pankaj Gupta wrote: >>> On 08/20/2014 07:17 PM, Michael S. Tsirkin wrote: >>>> On Wed, Aug 20, 2014 at 12:58:17PM +0200, Jiri Pirko wrote: >>>>>> Mon, Aug 18, 2014 at 03:37:18PM CEST, pagupta@redhat.com wrote: >>>>>>>> This patch publishes maximum number of tun/tap queues allocated as a >>>>>>>> read_only module parameter which a user space application like >>>>>>>> libvirt >>>>>>>> can make use of to limit maximum number of queues. Value of read_only >>>>>>>> module parameter can be writable only at module load time. If no >>>>>>>> value is set >>>>>>>> at module load time a default value 256 is used which is equal to >>>>>>>> maximum number >>>>>>>> of vCPUS allowed by KVM. >>>>>>>> >>>>>>>> Administrator can specify maximum number of queues only at the driver >>>>>>>> module load time. >>>>>>>> >>>>>>>> Signed-off-by: Pankaj Gupta <pagupta@redhat.com> >>>>>>>> --- >>>>>>>> drivers/net/tun.c | 13 +++++++++++-- >>>>>>>> 1 files changed, 11 insertions(+), 2 deletions(-) >>>>>>>> >>>>>>>> diff --git a/drivers/net/tun.c b/drivers/net/tun.c >>>>>>>> index acaaf67..1f518e2 100644 >>>>>>>> --- a/drivers/net/tun.c >>>>>>>> +++ b/drivers/net/tun.c >>>>>>>> @@ -119,6 +119,9 @@ struct tap_filter { >>>>>>>> >>>>>>>> #define TUN_FLOW_EXPIRE (3 * HZ) >>>>>>>> >>>>>>>> +static int max_tap_queues = MAX_TAP_QUEUES; >>>>>>>> +module_param(max_tap_queues, int, S_IRUGO); >>>>>> Please do not introduce new module paramaters. Please other ways to >>>>>> interchange values with userspace. >>>> I suggested this initially, but thinking more about it, I agree. >>>> >>>> It's a global limit (necessary to limit memory utilization by >>>> userspace), but it should be possible to change it >>>> after module load. >>> How about pass this limit through ifr during TUNSETIFF, then >>> alloc_netdev_mq() can use this limit. >> Any other ideas/comments from the experts. Or shall I re-repost other patches >> in the series except this patch until we agree on one. >> > It's kind of useless without a way for userspace to discover > how many queues it can create, no? >
We can implement ethtool_get_channels for tuntap. But I'm still not clear why this is necessary.
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