From: Nick Piggin <npiggin@suse.de>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Nick Piggin <npiggin@suse.de>,
Linux Memory Management <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Hugh Dickins <hugh@veritas.com>, Andrew Morton <akpm@osdl.org>,
Andrea Arcangeli <andrea@suse.de>,
David Miller <davem@davemloft.net>
Subject: Re: [patch 0/4] mm: de-skew page refcount
Date: Thu, 19 Jan 2006 15:00:39 +0100 [thread overview]
Message-ID: <20060119140039.GA958@wotan.suse.de> (raw)
In-Reply-To: <Pine.LNX.4.64.0601181122120.3240@g5.osdl.org>
On Wed, Jan 18, 2006 at 11:27:13AM -0800, Linus Torvalds wrote:
>
>
> On Wed, 18 Jan 2006, Nick Piggin wrote:
> >
> > > So I disagree with this patch series. It has real downsides. There's a
> > > reason we have the offset.
> >
> > Yes, there is a reason, I detailed it in the changelog and got rid of it.
>
> And I'm not applying it. I'd be crazy to replace good code by code that is
> objectively _worse_.
>
And you're not? Damn.
> The fact that you _document_ that it's worse doesn't make it any better.
>
> The places that you improve (in the other patches) seem to have nothing at
> all to do with the counter skew issue, so I don't see the point.
>
You know, I believe you're right. I needed the de-skewing patch for
something unrelated and it seemed that it opened the possibility for
the following optimisations (ie. because we no longer touch a page
after its refcount goes to zero).
But actually it doesn't matter that we might touch page_count, only
that we not clear PageLRU. So the enabler is simply moving the
TestClearPageLRU after the get_page_testone.
So I'll respin the patches without the de-skewing and the series
will become much smaller and neater.
> So let me repeat: WHY DID YOU MAKE THE CODE WORSE?
>
You've never bothered me about that until now...
Thanks for the feedback!
Nick
next prev parent reply other threads:[~2006-01-19 14:00 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-18 10:40 [patch 0/4] mm: de-skew page refcount Nick Piggin
2006-01-18 10:40 ` [patch 1/4] mm: page refcount use atomic primitives Nick Piggin
2006-01-18 10:40 ` [patch 2/4] mm: PageLRU no testset Nick Piggin
2006-01-19 17:48 ` Nikita Danilov
2006-01-19 18:10 ` Nick Piggin
2006-01-18 10:40 ` [patch 3/3] mm: PageActive " Nick Piggin
2006-01-18 14:13 ` Marcelo Tosatti
2006-01-19 14:50 ` Nick Piggin
2006-01-19 16:52 ` Marcelo Tosatti
2006-01-19 20:02 ` Nick Piggin
2006-01-19 21:41 ` Marcelo Tosatti
2006-01-18 10:41 ` [patch 4/4] mm: less atomic ops Nick Piggin
2006-01-18 16:38 ` [patch 0/4] mm: de-skew page refcount Linus Torvalds
2006-01-18 17:05 ` Nick Piggin
2006-01-18 19:27 ` Linus Torvalds
2006-01-19 14:00 ` Nick Piggin [this message]
2006-01-19 16:36 ` Linus Torvalds
2006-01-19 17:06 ` Nick Piggin
2006-01-19 17:27 ` Linus Torvalds
2006-01-19 17:38 ` Nick Piggin
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