From: Jason Wang <jasowang@redhat.com>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
Jakub Kicinski <kuba@kernel.org>
Cc: virtualization@lists.linux-foundation.org,
Network Development <netdev@vger.kernel.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
Richard Cochran <richardcochran@gmail.com>
Subject: Re: [PATCH rfc 2/3] virtio-net: support receive timestamp
Date: Wed, 30 Dec 2020 16:44:17 +0800 [thread overview]
Message-ID: <10395a75-fb31-639f-40b2-d6fd60938247@redhat.com> (raw)
In-Reply-To: <CA+FuTSe630QvTRM-0fnz=B+QRfii=sbsb-Qp5tTc2zbMgxcQyw@mail.gmail.com>
On 2020/12/29 上午8:57, Willem de Bruijn wrote:
> On Mon, Dec 28, 2020 at 5:59 PM Jakub Kicinski <kuba@kernel.org> wrote:
>> On Mon, 28 Dec 2020 11:22:32 -0500 Willem de Bruijn wrote:
>>> From: Willem de Bruijn <willemb@google.com>
>>>
>>> Add optional PTP hardware timestamp offload for virtio-net.
>>>
>>> Accurate RTT measurement requires timestamps close to the wire.
>>> Introduce virtio feature VIRTIO_NET_F_RX_TSTAMP. If negotiated, the
>>> virtio-net header is expanded with room for a timestamp. A host may
>>> pass receive timestamps for all or some packets. A timestamp is valid
>>> if non-zero.
>>>
>>> The timestamp straddles (virtual) hardware domains. Like PTP, use
>>> international atomic time (CLOCK_TAI) as global clock base. It is
>>> guest responsibility to sync with host, e.g., through kvm-clock.
>> Would this not be confusing to some user space SW to have a NIC with
>> no PHC deliver HW stamps?
>>
>> I'd CC Richard on this, unless you already discussed with him offline.
> Thanks, good point. I should have included Richard.
>
> There is a well understood method for synchronizing guest and host
> clock in KVM using ptp_kvm. For virtual environments without NIC
> hardware offload, the when host timestamps in software, this suffices.
>
> Syncing host with NIC is assumed if the host advertises the feature
> and implements using real hardware timestamps.
Or it could be useful for virtio hardware when there's no KVM that
provides PTP.
Thanks
>
WARNING: multiple messages have this Message-ID (diff)
From: Jason Wang <jasowang@redhat.com>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
Jakub Kicinski <kuba@kernel.org>
Cc: Network Development <netdev@vger.kernel.org>,
Richard Cochran <richardcochran@gmail.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH rfc 2/3] virtio-net: support receive timestamp
Date: Wed, 30 Dec 2020 16:44:17 +0800 [thread overview]
Message-ID: <10395a75-fb31-639f-40b2-d6fd60938247@redhat.com> (raw)
In-Reply-To: <CA+FuTSe630QvTRM-0fnz=B+QRfii=sbsb-Qp5tTc2zbMgxcQyw@mail.gmail.com>
On 2020/12/29 上午8:57, Willem de Bruijn wrote:
> On Mon, Dec 28, 2020 at 5:59 PM Jakub Kicinski <kuba@kernel.org> wrote:
>> On Mon, 28 Dec 2020 11:22:32 -0500 Willem de Bruijn wrote:
>>> From: Willem de Bruijn <willemb@google.com>
>>>
>>> Add optional PTP hardware timestamp offload for virtio-net.
>>>
>>> Accurate RTT measurement requires timestamps close to the wire.
>>> Introduce virtio feature VIRTIO_NET_F_RX_TSTAMP. If negotiated, the
>>> virtio-net header is expanded with room for a timestamp. A host may
>>> pass receive timestamps for all or some packets. A timestamp is valid
>>> if non-zero.
>>>
>>> The timestamp straddles (virtual) hardware domains. Like PTP, use
>>> international atomic time (CLOCK_TAI) as global clock base. It is
>>> guest responsibility to sync with host, e.g., through kvm-clock.
>> Would this not be confusing to some user space SW to have a NIC with
>> no PHC deliver HW stamps?
>>
>> I'd CC Richard on this, unless you already discussed with him offline.
> Thanks, good point. I should have included Richard.
>
> There is a well understood method for synchronizing guest and host
> clock in KVM using ptp_kvm. For virtual environments without NIC
> hardware offload, the when host timestamps in software, this suffices.
>
> Syncing host with NIC is assumed if the host advertises the feature
> and implements using real hardware timestamps.
Or it could be useful for virtio hardware when there's no KVM that
provides PTP.
Thanks
>
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next prev parent reply other threads:[~2020-12-30 8:45 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-28 16:22 [PATCH rfc 0/3] virtio-net: add tx-hash, rx-tstamp and tx-tstamp Willem de Bruijn
2020-12-28 16:22 ` Willem de Bruijn
2020-12-28 16:22 ` [PATCH rfc 1/3] virtio-net: support transmit hash report Willem de Bruijn
2020-12-28 16:22 ` Willem de Bruijn
2020-12-28 16:28 ` Michael S. Tsirkin
2020-12-28 16:28 ` Michael S. Tsirkin
2020-12-28 16:47 ` Willem de Bruijn
2020-12-28 16:47 ` Willem de Bruijn
2020-12-28 17:22 ` Michael S. Tsirkin
2020-12-28 17:22 ` Michael S. Tsirkin
2020-12-29 1:19 ` Willem de Bruijn
2020-12-29 1:19 ` Willem de Bruijn
2020-12-28 21:36 ` Michael S. Tsirkin
2020-12-28 21:36 ` Michael S. Tsirkin
2020-12-29 1:23 ` Willem de Bruijn
2020-12-29 1:23 ` Willem de Bruijn
2020-12-28 16:22 ` [PATCH rfc 2/3] virtio-net: support receive timestamp Willem de Bruijn
2020-12-28 16:22 ` Willem de Bruijn
2020-12-28 17:28 ` Michael S. Tsirkin
2020-12-28 17:28 ` Michael S. Tsirkin
2020-12-28 19:30 ` Willem de Bruijn
2020-12-28 19:30 ` Willem de Bruijn
2020-12-28 21:32 ` Michael S. Tsirkin
2020-12-28 21:32 ` Michael S. Tsirkin
2020-12-29 1:05 ` Willem de Bruijn
2020-12-29 1:05 ` Willem de Bruijn
2020-12-29 9:17 ` Jason Wang
2020-12-29 9:17 ` Jason Wang
2020-12-29 14:20 ` Willem de Bruijn
2020-12-29 14:20 ` Willem de Bruijn
2020-12-30 8:38 ` Jason Wang
2020-12-30 8:38 ` Jason Wang
2020-12-28 22:59 ` Jakub Kicinski
2020-12-29 0:57 ` Willem de Bruijn
2020-12-29 0:57 ` Willem de Bruijn
2020-12-30 8:44 ` Jason Wang [this message]
2020-12-30 8:44 ` Jason Wang
2020-12-30 12:30 ` Richard Cochran
2021-02-02 13:05 ` kernel test robot
2021-02-02 13:05 ` kernel test robot
2021-02-02 13:05 ` kernel test robot
2021-02-02 14:08 ` Michael S. Tsirkin
2021-02-02 14:08 ` Michael S. Tsirkin
2021-02-02 22:17 ` Willem de Bruijn
2021-02-02 22:17 ` Willem de Bruijn
2021-02-02 23:02 ` Michael S. Tsirkin
2021-02-02 23:02 ` Michael S. Tsirkin
2021-02-02 23:43 ` Willem de Bruijn
2021-02-02 23:43 ` Willem de Bruijn
2020-12-28 16:22 ` [PATCH rfc 3/3] virtio-net: support transmit timestamp Willem de Bruijn
2020-12-28 16:22 ` Willem de Bruijn
2020-12-30 12:38 ` Richard Cochran
2020-12-30 15:25 ` Willem de Bruijn
2020-12-30 15:25 ` Willem de Bruijn
2021-02-02 13:47 ` kernel test robot
2021-02-02 13:47 ` kernel test robot
2021-02-02 13:47 ` kernel test robot
2020-12-28 17:29 ` [PATCH rfc 0/3] virtio-net: add tx-hash, rx-tstamp and tx-tstamp Michael S. Tsirkin
2020-12-28 17:29 ` Michael S. Tsirkin
2020-12-28 19:51 ` Willem de Bruijn
2020-12-28 19:51 ` Willem de Bruijn
2020-12-28 21:38 ` Michael S. Tsirkin
2020-12-28 21:38 ` Michael S. Tsirkin
2020-12-29 1:14 ` Willem de Bruijn
2020-12-29 1:14 ` Willem de Bruijn
2021-01-06 20:32 ` Willem de Bruijn
2021-01-06 20:32 ` Willem de Bruijn
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