From: "Wu, Feng" <feng.wu@intel.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: "george.dunlap@eu.citrix.com" <george.dunlap@eu.citrix.com>,
"andrew.cooper3@citrix.com" <andrew.cooper3@citrix.com>,
"dario.faggioli@citrix.com" <dario.faggioli@citrix.com>,
"Wu, Feng" <feng.wu@intel.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
Subject: Re: [PATCH v4 2/6] VMX: Properly handle pi when all the assigned devices are removed
Date: Thu, 29 Sep 2016 03:08:16 +0000 [thread overview]
Message-ID: <E959C4978C3B6342920538CF579893F019881A55@SHSMSX104.ccr.corp.intel.com> (raw)
In-Reply-To: <57EBAEE90200007800113370@prv-mh.provo.novell.com>
> >>
> >> So you continue using pausing, and I continue to miss the argumentation
> >> of why you can't do without (even if previously the discussion was for
> >> patch 4, but it obviously applies here as well).
> >
> > I think this case is slightly different. Here we need to call
> > vmx_pi_list_cleanup()
> > to remove the vCPU from the blocking list if it is on the list. However, this
> > can be happened when vmx_vcpu_block() is called, hence we might incorrectly
> > add the vcpu to the blocking list while the last device is detached from the
> domain.
> > In fact, v2 gave some trick methods to handle this, and that was considered as
> > hard to maintain, so George suggested to use pause/unpause for this case,
> and I
> > also think it is easy and acceptable consider that devices detaching is not a
> > frequent action.
>
> Note how I said "I continue to miss the argumentation of why you
> can't do without" - I'm not opposed to pausing getting used here, but
> it needs to be at least briefly explained in the commit message. That's
> among other things so that (see that other thread) people can't later
> come and say "Hey, pausing is done in all sorts of situations, why
> won't you let me add some more pausing?"
Fair enough, I will elaborate a bit more on it.
Thanks,
Feng
>
> Jan
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next prev parent reply other threads:[~2016-09-29 3:08 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-21 2:37 [PATCH v4 0/6] VMX: Properly handle pi descriptor and per-cpu blocking list Feng Wu
2016-09-21 2:37 ` [PATCH v4 1/6] VMX: Statically assign two PI hooks Feng Wu
2016-09-26 11:37 ` Jan Beulich
2016-09-26 12:09 ` Jan Beulich
2016-09-28 6:48 ` Wu, Feng
2016-09-28 9:38 ` Jan Beulich
2016-10-09 8:30 ` Wu, Feng
2016-10-10 7:26 ` Jan Beulich
2016-09-21 2:37 ` [PATCH v4 2/6] VMX: Properly handle pi when all the assigned devices are removed Feng Wu
2016-09-26 11:46 ` Jan Beulich
2016-09-28 6:50 ` Wu, Feng
2016-09-28 9:52 ` Jan Beulich
2016-09-29 3:08 ` Wu, Feng [this message]
2016-09-21 2:37 ` [PATCH v4 3/6] VMX: Cleanup PI per-cpu blocking list when vcpu is destroyed Feng Wu
2016-09-21 2:37 ` [PATCH v4 4/6] VMX: Make sure PI is in proper state before install the hooks Feng Wu
2016-09-26 12:45 ` Jan Beulich
2016-09-28 6:50 ` Wu, Feng
2016-09-21 2:37 ` [PATCH v4 5/6] VT-d: No need to set irq affinity for posted format IRTE Feng Wu
2016-09-26 12:58 ` Jan Beulich
2016-09-28 6:51 ` Wu, Feng
2016-09-28 9:58 ` Jan Beulich
2016-10-09 5:35 ` Wu, Feng
2016-10-10 7:02 ` Jan Beulich
2016-10-10 22:55 ` Wu, Feng
2016-09-21 2:37 ` [PATCH v4 6/6] VMX: Fixup PI descritpor when cpu is offline Feng Wu
2016-09-26 13:03 ` Jan Beulich
2016-09-28 6:53 ` Wu, Feng
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