From: roopa <roopa@cumulusnetworks•com>
To: Thomas Graf <tgraf@suug•ch>
Cc: netdev@vger•kernel.org, jhs@mojatatu•com, davem@davemloft•net
Subject: Re: [PATCH net-next v3 1/2] rtnetlink: add new RTM_GETSTATS message to query stats
Date: Sat, 16 Apr 2016 18:50:16 -0700 [thread overview]
Message-ID: <5712EBD8.2060100@cumulusnetworks.com> (raw)
In-Reply-To: <20160416074910.GA2486@pox.localdomain>
On 4/16/16, 12:49 AM, Thomas Graf wrote:
> On 04/15/16 at 08:28pm, Roopa Prabhu wrote:
>> +static u16 rtnl_stats_calcit(struct sk_buff *skb, struct nlmsghdr *nlh)
>> +{
>> + struct net *net = sock_net(skb->sk);
>> + struct net_device *dev;
>> + u16 min_ifinfo_dump_size = 0;
>> + struct if_stats_msg *ifsm;
>> + u32 filter_mask;
>> +
>> + ifsm = nlmsg_data(nlh);
>> + filter_mask = ifsm->filter_mask;
>> +
>> + /* traverse the list of net devices and compute the minimum
>> + * buffer size based upon the filter mask.
>> + */
>> + list_for_each_entry(dev, &net->dev_base_head, dev_list) {
>> + min_ifinfo_dump_size = max_t(u16, min_ifinfo_dump_size,
>> + if_nlmsg_stats_size(dev,
>> + filter_mask));
>> + }
> Iterating over all net_devices in the namespace is quite an expensive
> operation and it would now be done twice.
>
> I understand that this code is taken over from rtnl_calcit() but there
> the cost is at least only paid if ext_filter_mask is actually set and
> the user opts into additional statistics.
>
> I wonder if we can reduce the cost for the stats interface as its
> purpose is to be minimal cost. I suggest we only add the loop once we
> have an extension which actually depends on it. We can then try and
> figure out to not require it.
ok, ack. Its not absolutely necessary right now with the one link filter stats
I am adding support for. We can bring it back later when we see a first instance
which makes it necessary.
In which case, I am going to trim down the series to absolute minimal.
just rtnl link stats64. I want to drop the ipv6 patch anyways.
With it I will also drop the general af stats handling. Will get it back when we get to the first
proper af stats implementation (hopefully mpls).
With this, the calcit for RTM_GETSTATS will be NULL, until we add the implementation for the other
stats attributes.
prev parent reply other threads:[~2016-04-17 1:50 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-16 3:28 [PATCH net-next v3 1/2] rtnetlink: add new RTM_GETSTATS message to query stats Roopa Prabhu
2016-04-16 7:49 ` Thomas Graf
2016-04-17 1:50 ` roopa [this message]
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