netdev - Re: [PATCH net-next] virtio_net: ethtool tx napi configuration

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Fri, 28 Sep 2018 07:39:57 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Network Development <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>, caleb.raitto@...il.com,
        "Michael S. Tsirkin" <mst@...hat.com>,
        "Jon Olson (Google Drive)" <jonolson@...gle.com>,
        Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net-next] virtio_net: ethtool tx napi configuration



On 2018年09月27日 21:53, Willem de Bruijn wrote:
> On Thu, Sep 27, 2018 at 4:51 AM Jason Wang <jasowang@...hat.com> wrote:
>>
>>
>> On 2018年09月14日 12:46, Willem de Bruijn wrote:
>>>> I'm not sure I get this. If we don't enable tx napi, we tend to delay TX
>>>> interrupt if we found the ring is about to full to avoid interrupt
>>>> storm, so we're probably ok in this case.
>>> I'm only concerned about the transition state when converting from
>>> napi to no-napi when the queue is stopped and tx interrupt disabled.
>>>
>>> With napi mode the interrupt is only disabled if napi is scheduled,
>>> in which case it will eventually reenable the interrupt. But when
>>> switching to no-napi mode in this state no progress will be made.
>>>
>>> But it seems this cannot happen. When converting to no-napi
>>> mode, set_coalesce waits for napi to complete in napi_disable.
>>> So the interrupt should always start enabled when transitioning
>>> into no-napi mode.
>> An update, I meet a hang in napi_disalbe(). But it's hard to be
>> reproduced. I tend to choose a easy way like V1 that only allow the
>> switching when device is down.
> I agree.
>
>> I will post the patch after a vacation. (or you can post if it was
>> urgent for you).
> If you have time to review and add your signed-off-by, I can post it.
> It's a pretty small diff at this point.
>
> But no rush, we can also wait until after your vacation.

Then let me post it after the vacation.

>
> I also need to look at a patch to toggle LRO using ethtool, btw.

Interesting, we've already did something similar during XDP. The 
GUEST_TSO_XXX part may need some private flags I believe.

Thanks