Maxime,
The
OK. Thanks. I am forwarding this to Pierre as he has been working on
vhost-user.
I thought we were now using dpdk's vhost-user driver as of 17.01.
It is interesting how we haven't seen this in our csit testing and we
are testing multi-queue. Also will this manifest only on certain
revisions of Qemu/KVM?
--TFH
-------- Forwarded Message --------
Subject: [Bug 1422534] vdev->vq[i] .used_idx does not consider the
right value for vhostuser
Date: Wed, 08 Mar 2017 08:56:49 +0000
From: bugzi...@redhat.com
To: therb...@redhat.com
https://bugzilla.redhat.com/show_bug.cgi?id=1422534
--- Comment #27 from Maxime Coquelin <maxime.coque...@redhat.com> ---
Tom,
I had a look at mainline VPP:
$ build-root/scripts/version
17.04-rc0~382-ga0b34a7
Looking at 16.06 release, it seems to be a regression, as the vring struct is
not reset before getting last_avail_idx, only the enable bit is cleared:
case VHOST_USER_GET_VRING_BASE:
DBG_SOCK("if %d msg VHOST_USER_GET_VRING_BASE idx %d num %d",
vui->hw_if_index, msg.state.index, msg.state.num);
/* Spec says: Client must [...] stop ring upon receiving
VHOST_USER_GET_VRING_BASE. */
vui->vrings[msg.state.index].enabled = 0;
msg.state.num = vui->vrings[msg.state.index].last_avail_idx;
msg.flags |= 4;
msg.size = sizeof(msg.state);
break;
The regression seems to have been introduced by below commit, which landed into
v17.01 release:
$ git blame src/vnet/devices/virtio/vhost-user.c -L 1031
e21c5286 vnet/vnet/devices/virtio/vhost-user.c (Pierre Pfister 2016-09-21
08:04:59 +0100 1031) vhost_user_vring_close (vui, msg.state.index);
$ git show e21c5286
commit e21c52861d7c503bef7fc464f23bbc7891e150d7
Author: Pierre Pfister <ppfis...@cisco.com>
Date: Wed Sep 21 08:04:59 2016 +0100
vhost-user: multiqueue support
This patch adds multi-queue support to non-dpdk's vhost-user
driver.
Waiting for a unified way to manage threads, this patch
defines a way to assign threads to interfaces that is
specific to vhost.
Change-Id: I86298788b1a4e886c5431f187dc17175d12c7a8b
Signed-off-by: Pierre Pfister <ppfis...@cisco.com>
$ git tag --contains e21c5286
v17.01
v17.01-rc1
v17.01-rc2
v17.01.1
v17.04-rc0
We should invite Pierre Pfister from Cisco in the discussion,
as he might have some ideas on the fix to do.
I guess that reverting to just clearing the enabled bit is not the right fix.
Maybe the vring struct shouldn't be re-initialized in the close function,
but should be called directly when needed.
I'm attaching a debug patch to confirm the root cause if someone want to have a
try.
It is not intended to be the fix for this issue, and has not neither been
compiled nor tested.
Regards,
Maxime
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