APPLIED Z: [SRU][Zesty][PATCH 0/1][v2]UBUNTU: SAUCE: Revert "vhost: cache used event for better performance"

[Stefan Bader]

On 01.09.2017 18:23, Joseph Salisbury wrote:
> BugLink: http://bugs.launchpad.net/bugs/1711251
> 
> == SRU Justification ==
> A vhost performance patch was introduced in the 4.10 kernel upstream, and 
> is currently included in the Zesty 4.10 kernel:
> 
> commit 809ecb9bca6a9424ccd392d67e368160f8b76c92
> Author: Jason Wang <jasowang at redhat.com>
> Date: Mon Dec 12 14:46:49 2016 +0800
> 
>     vhost: cache used event for better performance
> 
> However IBM recently hit a functional issue linked to this patch which 
> would cause random guests to lose their network connection under stress. 
> This is not architecture specific and more likely to be hit with high 
> network stress (i.e. lots of uperf instances).
> 
> The patch author has now reverted this patch upstream:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/vhost?id=8d65843c44269c21e95c98090d9bb4848d473853
> 
> Commit 809ecb9bca6a is reverted in mainline by commit 8d65843c44.   However, commit 8d65843c44 is not a clean cherry pick
> into Zesty, but a strait revert is clean.  This is because of a context diff in 
> vhost_notify(vhost_get_user was changed to vhose_get_avail by f88949138 in v4.11-rc1). 
> 
> == Fix ==
> Revert of upstream commit 809ecb9bca6a9424ccd392d67e368160f8b76c92.
> 
> == Test Case ==
> A test kernel was built with this revert and tested by the original bug reporter.
> The bug reporter states the test kernel resolved the bug.
> 
> 
> Joseph Salisbury (1):
>   Revert "vhost: cache used event for better performance"
> 
>  drivers/vhost/vhost.c | 28 ++++++----------------------
>  drivers/vhost/vhost.h |  3 ---
>  2 files changed, 6 insertions(+), 25 deletions(-)
> 
Applied v2 (with additional references and sob) to zesty master-next

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