On 16.10.2019 16:02, Flavio Leitner wrote:
On Wed, 16 Oct 2019 15:46:15 +0200
Maxime Coquelin <maxime.coque...@redhat.com> wrote:
On 10/16/19 3:32 PM, Ilya Maximets wrote:
On 16.10.2019 13:13, Maxime Coquelin wrote:
On 10/15/19 8:59 PM, Flavio Leitner wrote:
The rte_vhost_dequeue_burst supports two ways of dequeuing data.
If the data fits into a buffer, then all data is copied and a
single linear buffer is returned. Otherwise it allocates
additional mbufs and chains them together to return a multiple
segments mbuf.
While that covers most use cases, it forces applications that
need to work with larger data sizes to support multiple segments
mbufs. The non-linear characteristic brings complexity and
performance implications to the application.
To resolve the issue, add support to attach external buffer
to a pktmbuf and let the host provide during registration if
attaching an external buffer to pktmbuf is supported and if
only linear buffer are supported.
Signed-off-by: Flavio Leitner <f...@sysclose.org>
---
doc/guides/prog_guide/vhost_lib.rst | 35 +++++++++
lib/librte_vhost/rte_vhost.h | 4 +
lib/librte_vhost/socket.c | 22 ++++++
lib/librte_vhost/vhost.c | 22 ++++++
lib/librte_vhost/vhost.h | 4 +
lib/librte_vhost/virtio_net.c | 109
++++++++++++++++++++++++---- 6 files changed, 182 insertions(+),
14 deletions(-)
- Changelog:
v5:
- fixed to destroy mutex if incompatible flags
v4:
- allow to use pktmbuf if there is exact space
- removed log message if the buffer is too big
- fixed the length to include align padding
- free allocated buf if shinfo fails
v3:
- prevent the new features to be used with zero copy
- fixed sizeof() usage
- fixed log msg indentation
- removed/replaced asserts
- used the correct virt2iova function
- fixed the patch's title
- OvS PoC code:
https://github.com/fleitner/ovs/tree/rte_malloc-v3
v2:
- Used rte_malloc() instead of another mempool as suggested
by Shahaf.
- Added the documentation section.
- Using driver registration to negotiate the features.
- OvS PoC code:
https://github.com/fleitner/ovs/commit/8fc197c40b1d4fda331686a7b919e9e2b670dda7
Applied to dpdk-next-virtio/master.
Thanks Maxime,
But can we return back the mbuf allocation failure message?
Good point, I missed it.
I mean:
diff --git a/lib/librte_vhost/virtio_net.c
b/lib/librte_vhost/virtio_net.c index 66f0c7206..f8af4e0b3 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -1354,8 +1354,11 @@ virtio_dev_pktmbuf_alloc(struct virtio_net
*dev, struct rte_mempool *mp,
{
struct rte_mbuf *pkt = rte_pktmbuf_alloc(mp);
- if (unlikely(pkt == NULL))
+ if (unlikely(pkt == NULL)) {
+ RTE_LOG(ERR, VHOST_DATA,
+ "Failed to allocate memory for mbuf.\n");
return NULL;
+ }
if (rte_pktmbuf_tailroom(pkt) >= data_len)
return pkt;
---
It's a hard failure that highlights some significant issues with
memory pool size or a mbuf leak.
I agree, we need this error message.
If it runs out of memory and there are many packets coming, then it
will flood the logs. Maybe we could use something to report in a more
moderated way, for example:
diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index da69ab1db..b1572b3a4 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -1354,8 +1354,14 @@ virtio_dev_pktmbuf_alloc(struct virtio_net *dev, struct
rte_mempool *mp,
{
struct rte_mbuf *pkt = rte_pktmbuf_alloc(mp);
- if (unlikely(pkt == NULL))
+ if (unlikely(pkt == NULL)) {
+ static int rate_lim = 0;
+
+ if (rate_lim++ % 1000 == 0)
+ RTE_LOG...
+
return NULL;
+ }
if (rte_pktmbuf_tailroom(pkt) >= data_len)
return pkt;
Or track this at mempool level and keep stats of failed requests and
report that in OvS. That would cover other points too.
OVS is already rete-limiting DPDK logs. Basically, I introduced this
functionality to limit exactly this message.
See: 9fd38f6867df ("netdev-dpdk: Limit rate of DPDK logs.")
Best regards, Ilya Maximets.
