From: Jesse Brandeburg <jesse.brandeburg@intel.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
<linux-kernel@vger.kernel.org>, John <jw@nuclearfallout.net>
Subject: Re: [PATCH] irq: revert non-working patch to affinity defaults
Date: Fri, 3 Apr 2015 17:13:36 -0700 [thread overview]
Message-ID: <20150403171336.000075f2@unknown> (raw)
In-Reply-To: <20150403065557.GA12815@gmail.com>
On Fri, 3 Apr 2015 08:55:57 +0200
Ingo Molnar <mingo@kernel.org> wrote:
> So the original commit also has the problem that it unnecessary
> drops/retakes the descriptor lock:
>
> > irq_put_desc_unlock(desc, flags);
> > - /* set the initial affinity to prevent every interrupt being on CPU0 */
> > - if (m)
> > - __irq_set_affinity(irq, m, false);
>
>
> i.e. why not just call into irq_set_affinity_locked() while we still
> have the descriptor locked?
I had tried that but it didn't help much. I also tried kzalloc a new
descriptor like the proc functionality does, and that changes the
behavior a little, but doesn't fix it AFAICS.
> Now this is just a small annoyance that should not really matter - it
> would be nice to figure out the real reason for why the irqs move back
> to CPU#0.
>
> In theory the same could happen to 'irqbalanced' as well, if it calls
> shortly after an irq was registered - so this is not a bug we want to
> ignore.
Let me know if I can do something to help, the IRQ code is a bit of a
steep learning curve, so the chances of me fixing it are small.
> Also, worst case we are back to where v3.19 was, right? So could we
> try to analyze this a bit more?
Yes, 3.19 shipped with this issue. Again, let me know if I can help.
Thanks,
Jesse
next prev parent reply other threads:[~2015-04-04 0:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-03 0:50 [PATCH] irq: revert non-working patch to affinity defaults Jesse Brandeburg
2015-04-03 6:55 ` Ingo Molnar
2015-04-04 0:13 ` Jesse Brandeburg [this message]
2015-04-04 9:34 ` Ingo Molnar
2015-04-04 9:51 ` John
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