Hi yunhong, I agree with you of the taking I/O bandwidth as a resource, but it may be not so easy to implement. Your another thinking about the launch time may be not so terrible, only the first boot it will be affected.
2014-02-17 Wangpan 发件人:yunhong jiang <yunhong.ji...@linux.intel.com> 发送时间:2014-02-15 08:21 主题:Re: [openstack-dev] [nova] Should we limit the disk IO bandwidth in copy_image while creating new instance? 收件人:"OpenStack Development Mailing List (not for usage questions)"<openstack-dev@lists.openstack.org> 抄送: On Fri, 2014-02-14 at 10:22 +0100, Sylvain Bauza wrote: > Instead of limitating the consumed bandwidth by proposiong a > configuration flag (yet another one, and which default value to be > set ?), I would propose to only decrease the niceness of the process > itself, so that other processes would get first the I/O access. > That's not perfect I assume, but that's a quick workaround limitating > the frustration. > > > -Sylvain > Decrease goodness is good for a short term, Some small concerns are, will that cause long launch time if the host is I/O intensive? And if launch time is billed also, then not fair for the new instance also. I think the ideal world is I/O QoS like through cgroup, take I/O bandwidth as a resource, and take the copy_image as an consumption of the I/O bandwidth resource. Thanks --jyh > > 2014-02-14 4:52 GMT+01:00 Wangpan <hzwang...@corp.netease.com>: > Currently nova doesn't limit the disk IO bandwidth in > copy_image() method while creating a new instance, so the > other instances on this host may be affected by this high disk > IO consuming operation, and some time-sensitive business(e.g > RDS instance with heartbeat) may be switched between master > and slave. > > So can we use the `rsync --bwlimit=${bandwidth} src dst` > command instead of `cp src dst` while copy_image in > create_image() of libvirt driver, the remote image copy > operation also can be limited by `rsync --bwlimit= > ${bandwidth}` or `scp -l=${bandwidth}`, this parameter > ${bandwidth} can be a new configuration in nova.conf which > allow cloud admin to config it, it's default value is 0 which > means no limitation, then the instances on this host will be > not affected while a new instance with not cached image is > creating. > > the example codes: > nova/virt/libvit/utils.py: > diff --git a/nova/virt/libvirt/utils.py > b/nova/virt/libvirt/utils.py > index e926d3d..5d7c935 100644 > --- a/nova/virt/libvirt/utils.py > +++ b/nova/virt/libvirt/utils.py > @@ -473,7 +473,10 @@ def copy_image(src, dest, host=None): > # sparse files. I.E. holes will not be written to > DEST, > # rather recreated efficiently. In addition, since > # coreutils 8.11, holes can be read efficiently too. > - execute('cp', src, dest) > + if CONF.mbps_in_copy_image > 0: > + execute('rsync', '--bwlimit=%s' % > CONF.mbps_in_copy_image * 1024, src, dest) > + else: > + execute('cp', src, dest) > else: > dest = "%s:%s" % (host, dest) > # Try rsync first as that can compress and create > sparse dest files. > @@ -484,11 +487,22 @@ def copy_image(src, dest, host=None): > # Do a relatively light weight test first, so > that we > # can fall back to scp, without having run out of > space > # on the destination for example. > - execute('rsync', '--sparse', '--compress', > '--dry-run', src, dest) > + if CONF.mbps_in_copy_image > 0: > + execute('rsync', '--sparse', '--compress', > '--dry-run', > + '--bwlimit=%s' % > CONF.mbps_in_copy_image * 1024, src, dest) > + else: > + execute('rsync', '--sparse', '--compress', > '--dry-run', src, dest) > except processutils.ProcessExecutionError: > - execute('scp', src, dest) > + if CONF.mbps_in_copy_image > 0: > + execute('scp', '-l', '%s' % > CONF.mbps_in_copy_image * 1024 * 8, src, dest) > + else: > + execute('scp', src, dest) > else: > - execute('rsync', '--sparse', '--compress', src, > dest) > + if CONF.mbps_in_copy_image > 0: > + execute('rsync', '--sparse', '--compress', > + '--bwlimit=%s' % > CONF.mbps_in_copy_image * 1024, src, dest) > + else: > + execute('rsync', '--sparse', '--compress', > src, dest) > > > 2014-02-14 > > ______________________________________________________________ > Wangpan > > _______________________________________________ > OpenStack-dev mailing list > OpenStack-dev@lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > > > > _______________________________________________ > OpenStack-dev mailing list > OpenStack-dev@lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
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