Re: [PATCH v2 00/17] xen: support per-cpupool scheduling granularity

[Jürgen Groß <jgross@xxxxxxxx>]

On 05.12.20 00:53, Andrew Cooper wrote:
> On 01/12/2020 08:21, Juergen Gross wrote:
> > Support scheduling granularity per cpupool. Setting the granularity is
> > done via hypfs, which needed to gain dynamical entries for that
> > purpose.
> >
> > Apart from the hypfs related additional functionality the main change
> > for cpupools was the support for moving a domain to a new granularity,
> > as this requires to modify the scheduling unit/vcpu relationship.
> >
> > I have tried to do the hypfs modifications in a rather generic way in
> > order to be able to use the same infrastructure in other cases, too
> > (e.g. for per-domain entries).
> >
> > The complete series has been tested by creating cpupools with different
> > granularities and moving busy and idle domains between those.
> >
> > Changes in V2:
> > - Added several new patches, especially for some further cleanups in
> >    cpupool.c.
> > - Completely reworked the locking scheme with dynamical directories:
> >    locking of resources (cpupools in this series) is now done via new
> >    callbacks which are called when traversing the hypfs tree. This
> >    removes the need to add locking to each hypfs related cpupool
> >    function and it ensures data integrity across multiple callbacks.
> > - Reordered the first few patches in order to have already acked
> >    patches in pure cleanup patches first.
> > - Addressed several comments.
> >
> > Juergen Gross (17):
> >    xen/cpupool: add cpu to sched_res_mask when removing it from cpupool
> >    xen/cpupool: add missing bits for per-cpupool scheduling granularity
> >    xen/cpupool: sort included headers in cpupool.c
> >    xen/cpupool: switch cpupool id to unsigned
> >    xen/cpupool: switch cpupool list to normal list interface
> >    xen/cpupool: use ERR_PTR() for returning error cause from
> >      cpupool_create()
> >    xen/cpupool: support moving domain between cpupools with different
> >      granularity
> >    docs: fix hypfs path documentation
> >    xen/hypfs: move per-node function pointers into a dedicated struct
> >    xen/hypfs: pass real failure reason up from hypfs_get_entry()
> >    xen/hypfs: add getsize() and findentry() callbacks to hypfs_funcs
> >    xen/hypfs: add new enter() and exit() per node callbacks
> >    xen/hypfs: support dynamic hypfs nodes
> >    xen/hypfs: add support for id-based dynamic directories
> >    xen/cpupool: add cpupool directories
> >    xen/cpupool: add scheduling granularity entry to cpupool entries
> >    xen/cpupool: make per-cpupool sched-gran hypfs node writable
> Gitlab CI is fairly (but not completely) reliably hitting an failure in
> ARM randconfig against this series only.
>
> https://gitlab.com/xen-project/patchew/xen/-/pipelines/225445864 is one
> example.
>
> Error is:
>
> cpupool.c:102:12: error: 'sched_gran_get' defined but not used
> [-Werror=unused-function]
>    102 | static int sched_gran_get(const char *str, enum sched_gran *mode)
>        |            ^~~~~~~~~~~~~~
Ah, this is without CONFIG_HYPFS.

Will fix.


Juergen

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