On 19.12.2019 12:06, Durrant, Paul wrote: >> -----Original Message----- >> From: Andrew Cooper <andrew.coop...@citrix.com> >> Sent: 19 December 2019 10:52 >> To: Durrant, Paul <pdurr...@amazon.com>; xen-devel@lists.xenproject.org >> Cc: Wei Liu <w...@xen.org>; Jan Beulich <jbeul...@suse.com>; Roger Pau Monné >> <roger....@citrix.com> >> Subject: Re: [Xen-devel] [PATCH] x86/save: reserve HVM save record numbers >> that have been consumed... >> >> On 19/12/2019 08:52, Durrant, Paul wrote: >>>> -----Original Message----- >>>> From: Xen-devel <xen-devel-boun...@lists.xenproject.org> On Behalf Of >>>> Andrew Cooper >>>> Sent: 18 December 2019 19:45 >>>> To: Durrant, Paul <pdurr...@amazon.com>; xen-devel@lists.xenproject.org >>>> Cc: Wei Liu <w...@xen.org>; Jan Beulich <jbeul...@suse.com>; Roger Pau >> Monné >>>> <roger....@citrix.com> >>>> Subject: Re: [Xen-devel] [PATCH] x86/save: reserve HVM save record >> numbers >>>> that have been consumed... >>>> >>>> On 18/12/2019 16:09, Paul Durrant wrote: >>>>> ...for patches not (yet) upstream. >>>>> >>>>> This patch is simply reserving save record number space to avoid the >>>>> risk of clashes between existent downstream changes made by Amazon and >>>>> future upstream changes which may be incompatible. >>>>> >>>>> Signed-off-by: Paul Durrant <pdurr...@amazon.com> >>>> Is this "you've already used some of these", or you plan to? >>> Already used in code that has been deployed, although I have left some >> headroom because I know there is code in development which is using new >> ones. >>> >>> Where records can be upstreamed in a way that is compatible with >> downstream use, we will keep the existing number. If incompatible changes >> are necessary to get the code upstream then we will have to use a new >> number and maintain downstream compatibility patches. >> >> Every bump to this number is more wasted memory in Xen. > > How much more memory?
It is, btw, not just memory, but also a higher number of loop iterations. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
