Re: [libvirt] [PATCH 2/2]blkio: change the minimum weight according to kernel version
-----Original Message-----
From: Eric Blake [mailto:eblake@redhat.com]
Sent: Wednesday, October 09, 2013 11:52 AM
To: Chen Hanxiao
Cc: libvir-list(a)redhat.com
Subject: Re: [libvirt] [PATCH 2/2]blkio: change the minimum weight according to
kernel version
On 10/08/2013 02:38 AM, Chen Hanxiao wrote:
> From: Chen Hanxiao <chenhanxiao(a)cn.fujitsu.com>
>
> kernel had changed the minimum weight of device blkio from
> 100 to 10 in commit df457f845e5449be2e7d96668791f789b3770ac7.
> So we should to use new blkio weight range after 2.6.39.
Why not do it unconditionally, and then just have graceful error
detection when on older kernels when the input is rejected by the kernel
as out of range? That would be feature-based instead of version-check
based, which makes it more reliable even if the feature of the kernel is
backported to something that uname reports as having an older version
number.
How about just add the range to the doc and tell users that the range was changed.
Since the kernel will check whether the value is valid or not,
how do you think we leave this to kernel and check the errno?
That means libvirt did not check the input value ranges, send it to kernel and catch the
error.
Then we could not care how kernel would change its range.
Thanks
>
> libvirt should follow kernel according to
> kernel version.
>
> Signed-off-by: Gao feng <gaofeng(a)cn.fujitsu.com>
> Signed-off-by: Chen Hanxiao <chenhanxiao(a)cn.fujitsu.com>
> ---
> src/util/vircgroup.c | 44 +++++++++++++++++++++++++++++++++-----------
> 1 file changed, 33 insertions(+), 11 deletions(-)
Incomplete. You also need to touch virsh.pod and probably
formatdomain.html.in to document the larger range, and mention that
different connections may have different ranges (due to different kernel
versions on the other ends of those two connections).
Thanks. I will add these in the next patch.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org