From: Linus Torvalds <torvalds@transmeta.com>
To: Andi Kleen <ak@muc.de>
Cc: Andrew Morton <andrewm@uow.edu.au>, linux-mm@kvack.org
Subject: Re: 3rd version of R/W mmap_sem patch available
Date: Tue, 20 Mar 2001 09:13:42 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.4.31.0103200911490.1605-100000@penguin.transmeta.com> (raw)
In-Reply-To: <20010320173349.A4839@fred.local>
On Tue, 20 Mar 2001, Andi Kleen wrote:
> >
> > I don't think it's worth it. We should have basically zero contention on
> > this lock now, and adding complexity to try to release it sounds like a
> > bad idea when the only way to make contention on it is (a) kswapd (only
> > when paging stuff out) and (b) multiple threads (only when taking
> > concurrent page faults).
>
> Isn't (b) a rather common case in multi threaded applications ?
Not if you're performance-sensitive, I bet. If you take so many pagefaults
that the page_table_lock ends up being a problem, you have _more_ problems
than that.
We'll see. I will certainly re-consider if it ends up being shown to be a
real problem. spinlock contention tends to be very easy to see on kernel
profiles, especially the way they're done on Linux/x86 (inline - so you
see evrey contention place separately).
Linus
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next prev parent reply other threads:[~2001-03-20 17:13 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Pine.LNX.4.33.0103191802330.2076-100000@mikeg.weiden.de>
2001-03-20 1:56 ` Rik van Riel
2001-03-19 22:46 ` Linus Torvalds
2001-03-20 2:46 ` Linus Torvalds
2001-03-20 4:15 ` Marcelo Tosatti
2001-03-20 6:07 ` Linus Torvalds
2001-03-20 4:29 ` Marcelo Tosatti
2001-03-20 6:36 ` Linus Torvalds
2001-03-20 7:03 ` Linus Torvalds
2001-03-20 8:19 ` Eric W. Biederman
2001-03-20 15:11 ` Andrew Morton
2001-03-20 15:15 ` Jeff Garzik
2001-03-20 15:16 ` Jeff Garzik
2001-03-20 15:31 ` Andrew Morton
2001-03-21 1:59 ` Eric W. Biederman
2001-03-20 16:08 ` Linus Torvalds
2001-03-20 16:33 ` Andi Kleen
2001-03-20 17:13 ` Linus Torvalds [this message]
2001-03-20 19:33 ` Rik van Riel
2001-03-20 22:51 ` Andrew Morton
2001-03-22 10:24 ` Andrew Morton
2001-03-25 14:53 ` [patch] pae-2.4.3-A4 Ingo Molnar
2001-03-25 16:33 ` Russell King
2001-03-25 18:07 ` Linus Torvalds
2001-03-25 18:51 ` Ingo Molnar
[not found] <3AB6C7C2.D1A49FEF@uow.edu.au>
[not found] ` <Pine.LNX.4.31.0103191932240.7210-100000@penguin.transmeta.com>
2001-03-20 12:38 ` 3rd version of R/W mmap_sem patch available Stephen C. Tweedie
2001-03-20 14:02 ` H. Peter Anvin
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