From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: Maxime Coquelin <maxime.coquelin@redhat.com>
Cc: huawei.xie@intel.com, dev@dpdk.org, vkaplans@redhat.com, mst@redhat.com
Subject: Re: [dpdk-dev] [RFC] vhost: Add indirect descriptors support to the TX path
Date: Wed, 21 Sep 2016 10:41:13 +0800 [thread overview]
Message-ID: <20160921024113.GB23158@yliu-dev.sh.intel.com> (raw)
In-Reply-To: <e175edeb-87bf-56b8-9fc5-75783ea7be97@redhat.com>
On Fri, Aug 05, 2016 at 02:18:42PM +0200, Maxime Coquelin wrote:
>
>
> On 08/03/2016 04:03 PM, Yuanhan Liu wrote:
> >On Tue, Jul 12, 2016 at 04:32:12PM +0200, Maxime Coquelin wrote:
> >>Indirect descriptors are usually supported by virtio-net devices,
> >>allowing to dispatch a large number of large requests.
> >>
> >>When the virtio device sends a packet using indirect descriptors,
> >>only one slot is used in the ring, even for large packets.
> >>
> >>Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> >>---
> >>I have a two questions regarding the implementation of this feature:
> >>
> >>1. Should I add a check to ensure the indirect feature is supported
> >>(i.e. the negociation succeeded) when having an indirect desc?
> >>
> >>2. Should I check in copy_desc_to_mbuf() that we don't have a nested
> >>indirect descriptor?
> >>
> >>Both these sanity checks are recommended from the virtio spec, but
> >>since it is to be done in the hot path, it may introduce some
> >>performance penalties.
> >>
> >>Note that the first check is not done in the Kernel vhost driver, whereas
> >>the second one is.
> >
> >I think we could firstly follow the Linux kernel implementation.
> OK, I can do that in the v2.
FYI, I'm waiting for it.
--yliu
prev parent reply other threads:[~2016-09-21 2:40 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-12 14:32 Maxime Coquelin
2016-08-03 14:03 ` Yuanhan Liu
2016-08-05 12:18 ` Maxime Coquelin
2016-09-21 2:41 ` Yuanhan Liu [this message]
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