From: Pantelis Antoniou <panto@intracom•gr>
To: Benjamin Herrenschmidt <benh@kernel•crashing.org>
Cc: linux-ppc-embedded <linuxppc-embedded@ozlabs•org>
Subject: Re: [PATCH] 8xx: map_page() skip pinned region and tlbie debugging aid
Date: Fri, 01 Jul 2005 10:01:59 +0300 [thread overview]
Message-ID: <42C4EA67.4070601@intracom.gr> (raw)
In-Reply-To: <1120174169.31924.55.camel@gaston>
Benjamin Herrenschmidt wrote:
> On Thu, 2005-06-30 at 14:05 -0400, Dan Malek wrote:
>
>>On Jun 29, 2005, at 7:31 PM, Benjamin Herrenschmidt wrote:
>>
>>
>>> - The debate between Dan and me here is about the semantics of
>>>io_block_mapping().
>>
>>My point of discussion is this function needs to be much smarter than
>>simply allocating a virtual address space. We need to track the calls
>>so that we can "grow" previous spaces. A single io_block_mapping()
>>should not always allocate a new BAT, CAM or otherwise wired entry.
>>It has to know the alignment, size and amount of resource available.
>>For example, if an io_block_mapping() requests a 4M space, and it
>>isn't possible to wire such a size, we still need to keep track of that
>>such that a subsequent 4M request is combined into a space that
>>can be wired with an 8M entry. We need to make it smart enough
>>to coalesce the spaces to maximize the use of the available and
>>minimal mapping resources. If io_block_mapping() is just a simple
>>functions that decrements a pointer and sets a value in a register,
>>then you have already required the caller to know everything about
>>the mapping details, so why bother performing "hidden" arithmetic
>>that is likely to be known by the caller? If we are going to change
>>this
>
>
> Everyting ... but the virtual address, which is quite a bit :) My
> problem is really with virtual addresses beeing hard coded, which makes
> things complicated every time we try to do something with the kenrel
> virtual space. But ....
>
>
>>let's make it tru
>>y useful, so it understands the capabilities of the
>>processor, optimizes the resources, and keeps generic mapping
>>information so ioremap() doesn't care if it is mapped by BATs, CAMs,
>>or large pages.
>
>
> ... I do agree that making it even smarter so it can coalesce block
> mappings with the same attributes would be "interesting".
>
> Ben.
>
>
Let me pop in here.
My remote heap allocator has these properties, i.e. it can
coalesce adjucent areas if they are of the same "key".
Back to the depths which I now reside...
Regards
Pantelis
next prev parent reply other threads:[~2005-07-01 7:07 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-06-25 14:53 [PATCH] 8xx: map_page() skip pinned region and tlbie debugging aid Marcelo Tosatti
2005-06-25 22:24 ` Dan Malek
2005-06-26 14:30 ` Marcelo Tosatti
2005-06-27 13:39 ` Marcelo Tosatti
2005-06-27 20:46 ` Dan Malek
2005-06-28 6:30 ` Benjamin Herrenschmidt
2005-06-28 13:42 ` [PATCH] 8xx: get_mmu_context() for (very) FEW_CONTEXTS and KERNEL_PREEMPT race/starvation issue Guillaume Autran
2005-06-29 4:15 ` Benjamin Herrenschmidt
2005-06-29 15:32 ` Guillaume Autran
2005-06-29 15:54 ` Marcelo Tosatti
2005-06-29 21:25 ` Guillaume Autran
2005-06-29 17:00 ` Marcelo Tosatti
2005-06-29 23:26 ` Benjamin Herrenschmidt
2005-06-29 19:38 ` Marcelo Tosatti
2005-06-30 13:54 ` Guillaume Autran
2005-07-05 13:12 ` Guillaume Autran
2005-06-30 0:34 ` Eugene Surovegin
2005-06-29 23:24 ` Benjamin Herrenschmidt
2005-06-28 13:53 ` [PATCH] 8xx: map_page() skip pinned region and tlbie debugging aid Dan Malek
2005-06-28 23:47 ` Benjamin Herrenschmidt
2005-06-29 17:19 ` Marcelo Tosatti
2005-06-29 23:31 ` Benjamin Herrenschmidt
2005-06-30 18:05 ` Dan Malek
2005-06-30 23:29 ` Benjamin Herrenschmidt
2005-07-01 7:01 ` Pantelis Antoniou [this message]
2005-06-30 17:49 ` Dan Malek
2005-06-27 14:28 ` [PATCH] 8xx: tlbie debugging aid (try #2) Marcelo Tosatti
2005-06-27 20:18 ` Dan Malek
2005-06-27 14:56 ` Marcelo Tosatti
2005-06-27 20:53 ` Dan Malek
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