Re: [PATCH 0/8] tools/xenstored: add support for watch depth feature

[Juergen Gross <jgross@xxxxxxxx>]

Regarding the upcoming feature freeze, would it be possible to get some
feedback on this series?

I would really appreciate if at least the first 3 patches could make it
into 4.22, as this will avoid the need to bump the libxenstore minor
version in 4.23 again.


Juergen

On 13.03.26 08:47, Juergen Gross wrote:
> In order to reduce excessive number of watch events the watch depth
> feature has been defined, allowing the user to limit the number of
> node levels below the watched node to cause events.
>
> This series is implementing this feature for xenstored (including the
> PV and PVH stubdom variants).
>
> Possible users are:
>
> - xl/libxl: use domid information for the special @introduceDomain and
>    @releaseDomain watches, which will be available when using depth = 1
>
> - xenconsoled, like xl/libxl
>
> - any PV-device backends watching directories for added devices (no
>    watch events when any device specific node is modified)
>
> - any PV-device frontend and backend watching the "state" node of the
>    other side, in case the other side plays dirty games by building
>    large sub-trees beneath the "state" node
>
> This series has been tested with a modified xenstore-watch client.
> The modification will be sent as soon as the pending series of the
> xs-clients has been applied.
>
> Note that the watch depth series depends on the still pending series
> "tools: add support for per-domain xenstore quota".
>
> Juergen Gross (8):
>    tools/xenstored: allow domU to get own features
>    docs: clarify Xenstore watch depth feature
>    tools/libs/store: add support to use watches with a depth parameter
>    tools/xenstored: add depth information to watches
>    tools/xenstored: add depth handling to XS_WATCH
>    tools/xenstored: replace the fire_watches() exact parameter
>    tools/xenstored: expand special watch handling with depth feature
>    tools/xenstored: make XENSTORE_SERVER_FEATURE_WATCHDEPTH available
>
>   docs/man/xl.cfg.5.pod.in         |   6 ++
>   docs/misc/xenstore.txt           |  14 ++-
>   tools/include/xenstore.h         |  16 +++
>   tools/libs/store/libxenstore.map |   2 +
>   tools/libs/store/xs.c            | 116 ++++++++++++++++++----
>   tools/xenstored/core.c           |  15 ++-
>   tools/xenstored/domain.c         |  64 +++++++++---
>   tools/xenstored/domain.h         |   2 +
>   tools/xenstored/lu.c             |   3 +
>   tools/xenstored/transaction.c    |  14 +--
>   tools/xenstored/transaction.h    |   4 +-
>   tools/xenstored/watch.c          | 161 ++++++++++++++++++++++---------
>   tools/xenstored/watch.h          |  10 +-
>   xen/include/public/io/xs_wire.h  |   2 +
>   14 files changed, 328 insertions(+), 101 deletions(-)

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