[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: [libvirt] [PATCH RFC 0/5] support cpu bandwidth in libvirt




On 06/15/2011 01:24 AM, Wen Congyang wrote:
> I need this feature immediately after CFS bandwidth patchset is merged into
> upstream kernel. So I prepare this patchset, and post it here for reviewing
> before CFS bandwidth is merged into upstream kernel.
> 
> quota is an optional attribute specified in microseconds not a percentage of period.
> 
> TODO:
> 1. quota should be in the range [1000, 18446744073709551(2^64/1000)] or less than 0.
>    But I only limit it less or equal than 2^64/1000. Does anyone have a better
>    way to limit quota?

What are the semantics of quota < 0, of quota == 0?  How are you storing
such a large signed integer in the kernel?  I will guess that any value
less than 0 means: no limit, and 0 means: no quota (ie. the cgroup
cannot run on the cpu).

I am not sure what the libvirt convention for dealing with a situation
like this is.  I think you have two options: 1) override an invalid
value (ie. 1) to represent the case (n < 0) or, 2) use a struct to
represent the quota:

struct _virCfsQuota {
    unsigned long long val;
    int unlimited;
};

When the quota is unlimited, .unlimited == 1 and val is undefined.
Otherwise, the quota is in val.


> 
> Wen Congyang (5):
>   cgroup: Implement cpu.cfs_period_us and cpu.cfs_quota_us tuning API
>   Update XML Schema for new entries
>   qemu: Implement period and quota tunable XML configuration and
>     parsing.
>   qemu: Implement cfs_period and cfs_quota's modification
>   doc: Add documentation for new cputune elements period and quota
> 
>  docs/formatdomain.html.in                       |   19 +++
>  docs/schemas/domain.rng                         |   25 ++++-
>  src/conf/domain_conf.c                          |   20 +++-
>  src/conf/domain_conf.h                          |    2 +
>  src/libvirt_private.syms                        |    4 +
>  src/qemu/qemu_cgroup.c                          |   43 +++++-
>  src/qemu/qemu_driver.c                          |  162 +++++++++++++++++++----
>  src/util/cgroup.c                               |   81 +++++++++++-
>  src/util/cgroup.h                               |    6 +
>  tests/qemuxml2argvdata/qemuxml2argv-cputune.xml |    2 +
>  10 files changed, 328 insertions(+), 36 deletions(-)

-- 
Adam Litke
IBM Linux Technology Center


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]