From: Jason Wang <jasowang@redhat.com>
To: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Cc: netdev@vger.kernel.org,
virtualization@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
mst@redhat.com
Subject: Re: [PATCH V2 4/6] vhost_net: determine whether or not to use zerocopy at one time
Date: Mon, 02 Sep 2013 11:15:14 +0800 [thread overview]
Message-ID: <522402C2.9000802@redhat.com> (raw)
In-Reply-To: <5220E606.8010008@cogentembedded.com>
On 08/31/2013 02:35 AM, Sergei Shtylyov wrote:
> Hello.
>
> On 08/30/2013 08:29 AM, Jason Wang wrote:
>
>> Currently, even if the packet length is smaller than
>> VHOST_GOODCOPY_LEN, if
>> upend_idx != done_idx we still set zcopy_used to true and rollback
>> this choice
>> later. This could be avoided by determine zerocopy once by checking all
>> conditions at one time before.
>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>> drivers/vhost/net.c | 46
>> +++++++++++++++++++---------------------------
>> 1 files changed, 19 insertions(+), 27 deletions(-)
>
>> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
>> index 8a6dd0d..ff60c2a 100644
>> --- a/drivers/vhost/net.c
>> +++ b/drivers/vhost/net.c
>> @@ -404,43 +404,35 @@ static void handle_tx(struct vhost_net *net)
>> iov_length(nvq->hdr, s), hdr_size);
>> break;
>> }
>> - zcopy_used = zcopy && (len >= VHOST_GOODCOPY_LEN ||
>> - nvq->upend_idx != nvq->done_idx);
>> +
>> + zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
>> + && (nvq->upend_idx + 1) % UIO_MAXIOV != nvq->done_idx
>> + && vhost_net_tx_select_zcopy(net);
>
> Could you leave && on a first of two lines, matching the previous
> style?
>
ok.
>>
>> /* use msg_control to pass vhost zerocopy ubuf info to skb */
>> if (zcopy_used) {
>> + struct ubuf_info *ubuf;
>> + ubuf = nvq->ubuf_info + nvq->upend_idx;
>> +
>> vq->heads[nvq->upend_idx].id = head;
> [...]
>> + vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
>> + ubuf->callback = vhost_zerocopy_callback;
>> + ubuf->ctx = nvq->ubufs;
>> + ubuf->desc = nvq->upend_idx;
>> + msg.msg_control = ubuf;
>> + msg.msg_controllen = sizeof(ubuf);
>
> 'sizeof(ubuf)' where 'ubuf' is a pointer? Are you sure it shouldn't
> be 'sizeof(*ubuf)'?
Yes, pointer is sufficiet. Vhost allocate an arrays of ubuf and
tun/macvtap just need a reference of it.
>
> WBR, Sergei
>
> --
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next prev parent reply other threads:[~2013-09-02 3:15 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-30 4:29 [PATCH V2 0/6] vhost code cleanup and minor enhancement Jason Wang
2013-08-30 4:29 ` [PATCH V2 1/6] vhost_net: make vhost_zerocopy_signal_used() returns void Jason Wang
2013-09-02 5:51 ` Michael S. Tsirkin
2013-09-02 6:29 ` Jason Wang
2013-08-30 4:29 ` [PATCH V2 2/6] vhost_net: use vhost_add_used_and_signal_n() in vhost_zerocopy_signal_used() Jason Wang
2013-09-02 5:50 ` Michael S. Tsirkin
2013-09-02 6:28 ` Jason Wang
2013-08-30 4:29 ` [PATCH V2 3/6] vhost: switch to use vhost_add_used_n() Jason Wang
2013-08-30 4:29 ` [PATCH V2 4/6] vhost_net: determine whether or not to use zerocopy at one time Jason Wang
2013-08-30 18:35 ` Sergei Shtylyov
2013-09-02 3:15 ` Jason Wang [this message]
2013-08-30 4:29 ` [PATCH V2 5/6] vhost_net: poll vhost queue after marking DMA is done Jason Wang
2013-08-30 16:44 ` Ben Hutchings
2013-09-02 3:06 ` Jason Wang
2014-02-12 7:38 ` Qin Chuanyu
[not found] ` <52FB24EA.3060001@huawei.com>
2014-02-12 10:06 ` Jason Wang
2014-02-12 16:01 ` Michael S. Tsirkin
2013-08-30 4:29 ` [PATCH V2 6/6] vhost_net: correctly limit the max pending buffers Jason Wang
2013-09-02 5:56 ` Michael S. Tsirkin
2013-09-02 6:30 ` Jason Wang
2013-09-02 8:37 ` Jason Wang
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