> -----Original Message----- > From: Julien Grall <jul...@xen.org> > Sent: 20 April 2020 15:15 > To: p...@xen.org; 'Jan Beulich' <jbeul...@suse.com>; > xen-devel@lists.xenproject.org > Cc: 'Andrew Cooper' <andrew.coop...@citrix.com>; 'George Dunlap' > <george.dun...@citrix.com>; 'Ian > Jackson' <ian.jack...@eu.citrix.com>; 'Stefano Stabellini' > <sstabell...@kernel.org>; 'Wei Liu' > <w...@xen.org> > Subject: Re: [PATCH 0/3] xenoprof: XSA-313 follow-up > > Hi Paul, > > On 15/04/2020 09:50, Paul Durrant wrote: > >> -----Original Message----- > >> From: Jan Beulich <jbeul...@suse.com> > >> Sent: 15 April 2020 09:45 > >> To: xen-devel@lists.xenproject.org > >> Cc: Andrew Cooper <andrew.coop...@citrix.com>; George Dunlap > >> <george.dun...@citrix.com>; Ian > Jackson > >> <ian.jack...@eu.citrix.com>; Julien Grall <jul...@xen.org>; Stefano > >> Stabellini > >> <sstabell...@kernel.org>; Wei Liu <w...@xen.org>; Paul Durrant > >> <p...@xen.org> > >> Subject: [PATCH 0/3] xenoprof: XSA-313 follow-up > >> > >> Patch 1 was considered to become part of the XSA, but it was then > >> decided against. The other two are a little bit of cleanup, albeit > >> there's certainly far more room for tidying. Yet then again Paul, > >> in his mail from Mar 13, was asking whether we shouldn't drop > >> xenoprof altogether, at which point cleaning up the code would be > >> wasted effort. > >> > > > > That's still my opinion. This is a large chunk of (only passively > > maintained) code which I think is > of very limited value (since it relates to an old tool, and it only works for > PV domains). > > While there are no active user we are aware of, this is an example on > how to implement a profiler backend with Xen. So I would agree with > Andrew here. > > IIRC, the reason behind your request is it makes difficult for your > xenheap work. Am I correct? If so, do you have a thread explaining the > issues?
After shared info and grant table, it is the only other occurrence of a xenheap page shared with a non-system domain. Also, it cannot be trivially replaced with an 'extra' domheap page because its assignment changes. Thus a whole bunch of cleanup work that I was hoping to do (largely in domain_relinquish_resources and free_domheap_pages) is either ruled out, or would have to special-case this type of page. Also, I am unconvinced that PV guests are sufficiently common these days (apart from dom0) that profiling them is of any real use. Paul
