From: Grant Likely <grant.likely@secretlab.ca>
To: Milton Miller <miltonm@bga.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC 06/14] irq_domain/powerpc: Eliminate virq_is_host()
Date: Wed, 18 Jan 2012 14:25:55 -0700 [thread overview]
Message-ID: <20120118212555.GO4223@ponder.secretlab.ca> (raw)
In-Reply-To: <keep-irq-is-domain@mdm.bga.com>
Some more thoughts...
On Thu, Jan 12, 2012 at 04:17:58AM -0600, Milton Miller wrote:
> On Wed Jan 11 2012 about 15:24:34 EST, Grant Likely wrote:
> > There is only one user, and it is trivial to open-code.
>
> I added virq_is_host because I had planned to change how we find the
> host (domain) from a virq.
>
> Instead of storing a pointer in irq_desc (a pointer for every irq),
> I planned to use a NR_IRQ(+extra) bitmap per domain. This should be
> a win storage-wise when the number of irq controllers is less than the
> number of bits in a long.
>
> This would also convert scanning for a reverse map from walking every
> irqdesc to walking find_next_bit over the irqs assigned to the host.
>From my reading of the code, this should no long be a concern for
anything except the radix revmap. Only the radix revmap has the song
and dance about deferring allocation of the revmap. The linear map in
immediately allocated and should always be available for mapping.
The only exception I could imagine is a linear hwirq mapping for a
hwirq number higher than the size of the revmap, but I don't think
that the code supports. As you mention below, it should be possible
to remove the fallback to linear search entirely.
> Thus my rule was "code outside kernel/irq must not touch domain";
> both the contents and how it was associated were abstracted.
Good rule. I'll consider this.
> Other planned changes included splitting the reverse lookup into
> domain dependent pieces, creating the ida for sparse map at domain
> creation time (init irq is after radix_tree_init as its used by the
> current irq code) so we never fall back to linear search. Linear
> populated the reverse map as the irq was assigned, and changed to
> a seperate subtype if it mapped an irq above the map size.
I don't think it's worthwhile to handle corner cases like irq above
the map size in the linear map. If that actually happens, then the
driver should probably switch to the tree revmap.
>
> I thought some of the domains would be split into seperate files
> selected by Kconfig, at least the sparse tree.
I might do that, we'll see how the file looks when I'm done.
g.
prev parent reply other threads:[~2012-01-18 21:25 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-11 20:22 [RFC 0/14] Finish up irq_domain generalization Grant Likely
2012-01-11 20:22 ` [RFC 01/14] dt: Make irqdomain less verbose Grant Likely
2012-01-11 20:22 ` [RFC 02/14] irq_domain: Make irq_domain structure match powerpc's irq_host Grant Likely
2012-01-11 20:22 ` [RFC 03/14] irq_domain: convert microblaze from irq_host to irq_domain Grant Likely
2012-01-11 20:22 ` [RFC 04/14] irq_domain/powerpc: Use common irq_domain structure instead of irq_host Grant Likely
2012-01-11 20:22 ` [RFC 05/14] irq_domain/powerpc: eliminate irq_map; use irq_alloc_desc() instead Grant Likely
2012-01-11 20:22 ` [RFC 06/14] irq_domain/powerpc: Eliminate virq_is_host() Grant Likely
2012-01-11 20:22 ` [RFC 07/14] irq_domain: Move irq_domain code from powerpc to kernel/irq Grant Likely
2012-01-11 20:22 ` [RFC 08/14] irqdomain: remove NO_IRQ from irq domain code Grant Likely
2012-01-11 20:22 ` [RFC 09/14] irq_domain: Remove references to old irq_host names Grant Likely
2012-01-11 20:22 ` [RFC 10/14] irq_domain: Replace irq_alloc_host() with revmap-specific initializers Grant Likely
2012-01-11 20:22 ` [RFC 11/14] powerpc: Eliminate NO_IRQ usage Grant Likely
2013-07-25 21:58 ` Geert Uytterhoeven
2013-07-26 3:56 ` Grant Likely
2013-08-23 13:18 ` Geert Uytterhoeven
2013-08-23 13:22 ` Geert Uytterhoeven
2012-01-11 20:22 ` [RFC 12/14] irq_domain: Add support for base irq and hwirq in legacy mappings Grant Likely
2012-01-13 0:37 ` Rob Herring
2012-01-13 0:53 ` Grant Likely
2012-01-11 20:22 ` [RFC 13/14] irq_domain: Remove 'new' irq_domain in favour of the ppc one Grant Likely
2012-01-11 21:15 ` Rob Herring
2012-01-11 21:27 ` Grant Likely
2012-01-13 0:31 ` Rob Herring
2012-01-13 0:47 ` Grant Likely
2012-01-13 0:53 ` Rob Herring
2012-01-13 2:20 ` Grant Likely
2012-01-17 2:43 ` Michael Bohan
2012-01-17 3:42 ` Benjamin Herrenschmidt
2012-01-18 0:28 ` Grant Likely
2012-01-18 2:16 ` Benjamin Herrenschmidt
2012-01-11 20:22 ` [RFC 14/14] irq_domain: Remove irq_domain_add_simple() Grant Likely
2012-01-11 21:39 ` [RFC 0/14] Finish up irq_domain generalization Randy Dunlap
2012-01-11 20:50 ` Grant Likely
2012-01-11 21:23 ` Grant Likely
2012-01-11 22:48 ` Randy Dunlap
2012-01-12 10:17 ` [RFC 06/14] irq_domain/powerpc: Eliminate virq_is_host() Milton Miller
2012-01-18 0:38 ` Grant Likely
2012-01-18 21:25 ` Grant Likely [this message]
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