From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Andi Kleen <ak@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>,
benh@kernel.crashing.org, torvalds@osdl.org, akpm@osdl.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] page table iterators
Date: Sun, 20 Feb 2005 23:35:25 +1100 [thread overview]
Message-ID: <4218840D.6030203@yahoo.com.au> (raw)
In-Reply-To: <20050217235719.GB31591@wotan.suse.de>
Andi Kleen wrote:
> On Thu, Feb 17, 2005 at 03:30:31PM -0800, David S. Miller wrote:
>
>>On Fri, 18 Feb 2005 00:03:42 +0100
>>Andi Kleen <ak@suse.de> wrote:
>>
>>
>>>And to be honest we only have about 6 or 7 of these walkers
>>>in the whole kernel. And 90% of them are in memory.c
>>>While doing 4level I think I changed all of them around several
>>>times and it wasn't that big an issue. So it's not that we
>>>have a big pressing problem here...
>>
>>It's super error prone. A regression added by your edit of these
>
>
> Actually it was in Nick's code (PUD layer ;-). But I won't argue
> that my code didn't have bugs too...
>
>
I won't look back to see where the error came from :) But
yeah it is equally (if not more) likely to have come from
me. And it probably did happen because all the code is
slightly different and hard to understand.
>>walkers for the 4level changes was only discovered and fixed
>>yesterday by the ppc folks.
>>
>>I absolutely support any change which consolidates these things.
>
>
> The problem is just that these walker macros when they
> do all the lazy walking stuff will be quite complicated.
> And I don't really want another uaccess.h-like macro mess.
>
> Yes currently they look simple, but that will change.
>
But even in that case, it will still be better to have the
extra complexity once in the macro rather than throughout mm/
> Open coding is probably the smaller evil.
>
> And they're really not changed that often.
>
It is not so much a matter of changing, so much as having 10
slightly different implementations.
I think it should be easier to go from the iterators patch to
perhaps more complex iterators, or some open coding, etc etc.
rather than try to put a big complex pt walker on top of these
10 different open coded implementations.
But perhaps I'm missing something you're not - I'd need to see
the lazy walking code I guess.
Nick
next prev parent reply other threads:[~2005-02-20 12:35 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-17 13:53 [PATCH 1/2] optimise copy page range Nick Piggin
2005-02-17 14:03 ` [PATCH 2/2] page table iterators Nick Piggin
2005-02-17 15:56 ` Linus Torvalds
2005-02-17 16:13 ` Nick Piggin
2005-02-17 19:43 ` Andi Kleen
2005-02-17 22:49 ` Benjamin Herrenschmidt
2005-02-17 23:03 ` Andi Kleen
2005-02-17 23:21 ` Benjamin Herrenschmidt
2005-02-17 23:34 ` Andi Kleen
2005-02-17 23:30 ` David S. Miller
2005-02-17 23:57 ` Andi Kleen
2005-02-20 12:35 ` Nick Piggin [this message]
2005-02-21 6:35 ` Hugh Dickins
2005-02-21 6:40 ` Andrew Morton
2005-02-21 7:09 ` Benjamin Herrenschmidt
2005-02-21 8:09 ` Nick Piggin
2005-02-21 9:04 ` Nick Piggin
2005-02-22 9:54 ` Nick Piggin
2005-02-23 2:06 ` Hugh Dickins
2005-02-23 4:31 ` David S. Miller
2005-02-23 4:49 ` Nick Piggin
2005-02-23 4:57 ` David S. Miller
2005-02-23 5:23 ` Nick Piggin
2005-02-23 23:52 ` Nick Piggin
2005-02-24 0:00 ` David S. Miller
2005-02-24 5:12 ` Hugh Dickins
2005-02-24 5:59 ` Nick Piggin
2005-02-24 11:58 ` Hugh Dickins
2005-02-24 19:33 ` David S. Miller
2005-02-25 10:44 ` Andi Kleen
2005-02-24 21:59 ` Nick Piggin
2005-02-24 22:32 ` Hugh Dickins
2005-02-24 22:52 ` Nick Piggin
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