Re: [libvirt][PATCH v4 0/3] introduce 'restrictive' mode in numatune

> -----Original Message----- > From: Martin Kletzander <mkletzan(a)redhat.com&gt; > Sent: Thursday, March 25, 2021 4:46 AM > To: Daniel P. Berrangé <berrange(a)redhat.com&gt; > Cc: Zhong, Luyao <luyao.zhong(a)intel.com>; libvir-list(a)redhat.com > Subject: Re: [libvirt][PATCH v4 0/3] introduce 'restrictive' mode in numatune > > On Tue, Mar 23, 2021 at 09:48:02AM +0000, Daniel P. Berrangé wrote: > >On Tue, Mar 23, 2021 at 10:59:02AM +0800, Luyao Zhong wrote: > >> Before this patch set, numatune only has three memory modes: > >> static, interleave and prefered. These memory policies are ultimately > >> set by mbind() system call. > >> > >> Memory policy could be 'hard coded' into the kernel, but none of > >> above policies fit our requirment under this case. mbind() support > >> default memory policy, but it requires a NULL nodemask. So obviously > >> setting allowed memory nodes is cgroups' mission under this case. > >> So we introduce a new option for mode in numatune named 'restrictive'. > >> > >> <numatune> > >> <memory mode="restrictive" nodeset="1-4,^3"/> > >> <memnode cellid="0" mode="restrictive" nodeset="1"/> > >> <memnode cellid="2" mode="restrictive" nodeset="2"/> </numatune> > > > >'restrictive' is rather a wierd name and doesn't really tell me what > >the memory policy is going to be. As far as I can tell from the > >patches, it seems this causes us to not set any memory alllocation > >policy at all. IOW, we're using some undefined host default policy. > > > >Given this I think we should be calling it either "none" or "default" > > > > I was against "default" because having such option possible, but the actual > default being different sounds stupid. Similarly "none" sounds like no > restrictions are applied or that it is the same as if nothing was specified. It is > funny to imagine the situation when I am explaining to someone how to achieve > this solution: > > "The default is 'strict', you need to explicitly set it to 'default'." > > or > > "What setting did you use?" > "None" > "As in no mode or in mode='none'?" > > As I said before, please come up with any name, but not these that are IMHO > actually more confusing. > Hi Daniel and Martin, thanks for your reply, just as Martin said current default mode is "strict", so "default" was deprecated at the beginning when I proposed this change. And actually we have cgroups restricting the memory resource so could we call this a "none" mode? I still don't have a better name. ☹

> > > >Regards, > >Daniel > >-- > >|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| > >|: https://libvirt.org -o- https://fstop138.berrange.com :| > >|: https://entangle-photo.org -o- > https://www.instagram.com/dberrange :| > >