On 06.03.2020 17:27, Paul Durrant wrote: >> -----Original Message----- >> From: Jan Beulich <jbeul...@suse.com> >> Sent: 06 March 2020 13:46 >> To: Paul Durrant <xadimg...@gmail.com> >> Cc: sstabell...@kernel.org; jul...@xen.org; volodymyr_babc...@epam.com; >> w...@xen.org; >> konrad.w...@oracle.com; andrew.coop...@citrix.com; ian.jack...@eu.citrix.com; >> george.dun...@citrix.com; xen-devel@lists.xenproject.org; 'David Woodhouse' >> <dw...@infradead.org> >> Subject: Re: [PATCH 2/2] domain: use PGC_extra domheap page for shared_info >> >> On 06.03.2020 14:41, Paul Durrant wrote: >>>> -----Original Message----- >>>> From: Jan Beulich <jbeul...@suse.com> >>>> Sent: 06 March 2020 13:36 >>>> To: Paul Durrant <xadimg...@gmail.com> >>>> Cc: sstabell...@kernel.org; jul...@xen.org; volodymyr_babc...@epam.com; >>>> w...@xen.org; >>>> konrad.w...@oracle.com; andrew.coop...@citrix.com; >>>> ian.jack...@eu.citrix.com; >>>> george.dun...@citrix.com; xen-devel@lists.xenproject.org; 'David >>>> Woodhouse' <dw...@infradead.org> >>>> Subject: Re: [PATCH 2/2] domain: use PGC_extra domheap page for shared_info >>>> >>>> On 06.03.2020 14:26, Paul Durrant wrote: >>>>>> From: Xen-devel <xen-devel-boun...@lists.xenproject.org> On Behalf Of >>>>>> Jan Beulich >>>>>> Sent: 06 March 2020 13:24 >>>>>> >>>>>> On 06.03.2020 14:13, Paul Durrant wrote: >>>>>>> My aim is to make the separation abundantly obvious by getting rid >>>>>>> of shared xenheap pages (for non-system domains at least) but I >>>>>>> can't do that before converting shared_info and grant shared/status >>>>>>> frames to domheap. >>>>>> >>>>>> Following David's various replies - instead of going this route of >>>>>> replacing the sharing of xenheap pages by different logic, the >>>>>> same ought to be achievable by making the backing allocations come >>>>>> from the correct pool? >>>>>> >>>>> >>>>> I still prefer the simplification of not having to clean up the >>>>> shared xenheap page list in domain_kill() so IMO it is still worth >>>>> it for that alone. >>>> >>>> I don't see anything very special with the cleaning up in >>>> domain_kill() / domain_relinquish_resources(). What I'd view as >>>> more desirable in this regard is the general fact of needing >>>> two lists. But you realize there's a downside to this as well? >>>> dump_pageframe_info() will reliably show _all_ Xen heap pages >>>> associated with a domain, but it will only ever show up to 10 >>>> pages on ->page_list for a domain that's not already being >>>> cleaned up. >>> >>> That's not much of a downside though I don't think. The xenheap >>> (or PGC_extra domheap pages) are 'special' and so info about >>> them ought to be available via an alternate dump function anyway >>> (and if not already, it can be added). >> >> Whatever you'd add, the logic would need to either traverse the >> entire ->page_list (can take very long) or have/use out of band >> information where such pages may have a record (fragile). >> > > But the shared xenheap pages in question are only shared info, or > grant table, so their information can be dumped separately. > I guess it makes more sense to add another patch into the series > to do explicit dump of shared_info and then exclude 'special' > pages from dump_pageframe_info().
Bu that's why I said "fragile" - new uses of such pages wouldn't automatically be picked up, whereas them all landing on xenpage_list made their dumping a reliable thing. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
