Re: [Xen-devel] [PATCH 0/3] libxl: domain destroy fixes

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, Mar 25, 2015 at 02:08:33PM -0600, Jim Fehlig wrote:
> This small series of patches fixes some issues wrt domain destroy in
> the libxl driver.  The primary motivation for this work is to
> prevent locking the virDomainObj during long running destroy operations
> on large memory domains.
> 
> Patch 1 moves job acquisition from libxlDomainStart to it's callers so
> they have more control over when the job is acquired.  Patch 2 fixes a
> few spots where we never acquired a job during domain destroy.  Patch 3
> contains the interesting change, where the virDomainObj is unlocked
> during the long-running destroy operation.
> 
> This series wraps up my work to improve parallel OpenStack Tempest runs
> against the libxl driver.  With libvirt.git master + this series + a
> patched libxl [1], I've successfully run a reproducer that was hitting
> the same issues encountered by Tempest.
> 
> [1] libxl commits from xen.git: 93699882d, f1335f0d, 4783c99a, 1c91d6fba,
> and 188e9c54.  I'll contact the stable branch maintainers and ask them
> to include these commits in the next Xen 4.4.x and 4.5.x releases.
> 
> Jim Fehlig (3):
>   libxl: Move job acquisition in libxlDomainStart to callers
>   libxl: acquire a job when destroying a domain
>   libxl: drop virDomainObj lock when destroying a domain

I am no expert at this- but I dug through the code to understand how
the job and locking is done and now I am more comfortable with it.

Since I am new to this I went through all of the the callsites (which used
the job now) from the driver to make sure that there are no chained calls
(one function calling another which also uses a mutex or job locking).

I only found one culprit (libxlDomainAutoCoreDump being called from
 libxlDomainShutdownThread).

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

> 
>  src/libxl/libxl_domain.c | 77 +++++++++++++++++++----------------------------
>  src/libxl/libxl_domain.h |  4 ---
>  src/libxl/libxl_driver.c | 78 
> ++++++++++++++++++++++++++++++++++++------------
>  3 files changed, 89 insertions(+), 70 deletions(-)
> 
> -- 
> 1.8.4.5
> 
> 
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