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From: Dario Faggioli <dfaggioli@suse.com>
To: "Jürgen Groß" <jgross@suse.com>, "Jan Beulich" <jbeulich@suse.com>
Cc: George Dunlap <george.dunlap@eu.citrix.com>,
	xen-devel@lists.xenproject.org, Meng Xu <mengxu@cis.upenn.edu>
Subject: Re: [Xen-devel] [PATCH 3/8] xen/sched: don't use irqsave locks in dumping functions
Date: Wed, 19 Feb 2020 16:47:54 +0100	[thread overview]
Message-ID: <c7177a105c0ffddf37e8db385e80720fee7078b4.camel@suse.com> (raw)
In-Reply-To: <5b7eee77-776b-1e5e-e25c-a783520748e1@suse.com>


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On Wed, 2020-02-19 at 16:02 +0100, Jürgen Groß wrote:
> On 19.02.20 15:27, Jan Beulich wrote:
> > On 13.02.2020 13:54, Juergen Gross wrote:
> > > All dumping functions invoked by the "runq" keyhandler are called
> > > with
> > > disabled interrupts,
> > 
> > Is this actually needed for anything? It means not servicing
> > interrupts for perhaps an extended period of time. Debug keys
> > aren't promised to be non-intrusive, but they also shouldn't
> > be more intrusive than really needed. Wouldn't it therefore
> > be better to keep locking as it is now, and instead make sure
> > interrupts get turned off elsewhere (if needed) for much
> > shorter periods of time?
> 
> Indeed this is the better option. I just checked the code and
> think blindly turning interrupts off is not needed.
> 
Well, yes... Assuming you are referring to the IRQ being disabled in
cpupool.c:dump_runq(), my impression is that we can get rid of that,
and leave the sched-specific code (more or less) as it is (for the sake
of runqueue lock irq-safety).

Regards
-- 
Dario Faggioli, Ph.D
http://about.me/dario.faggioli
Virtualization Software Engineer
SUSE Labs, SUSE https://www.suse.com/
-------------------------------------------------------------------
<<This happens because _I_ choose it to happen!>> (Raistlin Majere)


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  reply	other threads:[~2020-02-19 15:48 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-13 12:54 [Xen-devel] [PATCH 0/8] xen: don't let keyhandlers block indefinitely on locks Juergen Gross
2020-02-13 12:54 ` [Xen-devel] [PATCH 1/8] xen: make rangeset_printk() static Juergen Gross
2020-02-13 14:00   ` Jan Beulich
2020-02-13 12:54 ` [Xen-devel] [PATCH 2/8] xen: add using domlist_read_lock in keyhandlers Juergen Gross
2020-02-13 14:01   ` Jan Beulich
2020-02-13 14:09   ` George Dunlap
2020-02-18  5:42   ` Tian, Kevin
2020-02-13 12:54 ` [Xen-devel] [PATCH 3/8] xen/sched: don't use irqsave locks in dumping functions Juergen Gross
2020-02-19 12:40   ` Dario Faggioli
2020-02-19 14:27   ` Jan Beulich
2020-02-19 15:02     ` Jürgen Groß
2020-02-19 15:47       ` Dario Faggioli [this message]
2020-02-13 12:54 ` [Xen-devel] [PATCH 4/8] xen: add locks with timeouts for keyhandlers Juergen Gross
2020-03-05 15:25   ` Jan Beulich
2020-03-06  8:08     ` Jürgen Groß
2020-03-06  8:15       ` Jürgen Groß
2020-02-13 12:54 ` [Xen-devel] [PATCH 5/8] xen/sched: use keyhandler locks when dumping data to console Juergen Gross
2020-02-19 14:31   ` Dario Faggioli
2020-02-19 15:09     ` Jürgen Groß
2020-02-13 12:54 ` [Xen-devel] [PATCH 6/8] xen/common: " Juergen Gross
2020-02-13 12:54 ` [Xen-devel] [PATCH 7/8] xen/drivers: " Juergen Gross
2020-02-13 12:54 ` [Xen-devel] [PATCH 8/8] xen/x86: " Juergen Gross
2020-02-13 18:38 ` [Xen-devel] [PATCH 0/8] xen: don't let keyhandlers block indefinitely on locks Andrew Cooper
2020-02-14  6:05   ` Jürgen Groß
2020-02-14  9:37   ` Jan Beulich
2020-02-19 12:14     ` Julien Grall

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