From: Jan Beulich <jbeulich@suse.com>
To: "Jürgen Groß" <jgross@suse.com>
Cc: George Dunlap <george.dunlap@eu.citrix.com>,
xen-devel@lists.xenproject.org,
Dario Faggioli <dfaggioli@suse.com>
Subject: Re: [Xen-devel] [PATCH v2] xen/sched: add some diagnostic info in the run queue keyhandler
Date: Tue, 11 Feb 2020 18:04:10 +0100 [thread overview]
Message-ID: <464d4f4c-a7eb-d081-71f1-55f40de9bd9f@suse.com> (raw)
In-Reply-To: <a3aae1ec-0830-0d65-a53b-338e27fade95@suse.com>
On 11.02.2020 17:54, Jürgen Groß wrote:
> On 11.02.20 17:46, Jan Beulich wrote:
>> On 11.02.2020 14:10, Jürgen Groß wrote:
>>> On 11.02.20 14:01, Jan Beulich wrote:
>>>> On 11.02.2020 13:27, Juergen Gross wrote:
>>>>> When dumping the run queue information add some more data regarding
>>>>> current and (if known) previous vcpu for each physical cpu.
>>>>>
>>>>> With core scheduling activated the printed data will be e.g.:
>>>>>
>>>>> (XEN) CPUs info:
>>>>> (XEN) CPU[00] current=d[IDLE]v0, curr=d[IDLE]v0, prev=NULL
>>>>> (XEN) CPU[01] current=d[IDLE]v1
>>>>> (XEN) CPU[02] current=d[IDLE]v2, curr=d[IDLE]v2, prev=NULL
>>>>> (XEN) CPU[03] current=d[IDLE]v3
>>>>>
>>>>> Signed-off-by: Juergen Gross <jgross@suse.com>
>>>>> ---
>>>>> V2: add proper locking
>>>>
>>>> "Proper" is ambiguous in the context of dumping functions. In a
>>>> number of places we use try-lock, to avoid the dumping hanging
>>>> on something else monopolizing the lock. I'd like to suggest to
>>>> do so here, too.
>>>
>>> All the scheduler related dumping functions are using the "real" locks.
>>> So using trylock in this single case wouldn't help at all. Additionally
>>> using trylock only would make a crash during dumping the data more
>>> probable, so I'm not sure we want that.
>>
>> Why would it make a crash more likely? If you can't get the lock,
>> you'd simply skip dumping.
>
> Ah, okay, then I misunderstood your intention.
>
> I still think that this should be done not only in one place, but in a
> more general fashion. I'd rather give up only after some time trying
> (1 millisecond per default?) and apply the same scheme to all dumping
> functions.
>
> I can have a try for such a series if you agree on taking a more general
> approach.
Getting behavior consistent across key handlers would of course
be very nice.
Jan
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next prev parent reply other threads:[~2020-02-11 17:04 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-11 12:27 [Xen-devel] [PATCH v2] xen/sched: add some diagnostic info in the run queue keyhandler Juergen Gross
2020-02-11 13:01 ` Jan Beulich
2020-02-11 13:10 ` Jürgen Groß
2020-02-11 16:46 ` Jan Beulich
2020-02-11 16:54 ` Jürgen Groß
2020-02-11 17:04 ` Jan Beulich [this message]
2020-02-20 9:57 ` Dario Faggioli
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