From: David Woodhouse <dwmw2@infradead.org>
To: lord@sgi.com
Cc: linux-kernel@vger.rutgers.edu, linux-mm@kvack.org,
sct@redhat.com, riel@conectiva.com.br
Subject: Re: kmap_kiobuf()
Date: Wed, 28 Jun 2000 17:06:30 +0100 [thread overview]
Message-ID: <13214.962208390@cygnus.co.uk> (raw)
In-Reply-To: <200006281554.KAA19007@jen.americas.sgi.com>
lord@sgi.com said:
> I always knew it would go down like a ton of bricks, because of the
> TLB flushing costs. As soon as you have a multi-cpu box this operation
> gets expensive, the code could be changed to do lazy tlb flushes on
> unmapping the pages, but you still have the cost every time you set a
> mapping up.
Aha - is this why kmap uses a pre-allocated set of PTEs? I got about that
far before deciding I had no clue what was going on and giving up.
MM is not exactly my field - I just know I want to be able to lock down a
user's buffer and treat it as if it were in kernel-space, passing its
address to functions which expect kernel buffers.
--
dwmw2
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next prev parent reply other threads:[~2000-06-28 16:06 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-06-28 15:54 kmap_kiobuf() lord
2000-06-28 16:06 ` David Woodhouse [this message]
2000-06-28 16:24 ` kmap_kiobuf() Benjamin C.R. LaHaise
2000-06-28 18:07 ` kmap_kiobuf() Stephen C. Tweedie
2000-06-28 18:45 ` kmap_kiobuf() David Woodhouse
2000-06-29 9:09 ` kmap_kiobuf() Stephen C. Tweedie
2000-06-28 17:46 ` kmap_kiobuf() Stephen C. Tweedie
-- strict thread matches above, loose matches on Subject: below --
2000-06-28 20:16 kmap_kiobuf() lord
2000-06-28 21:22 ` kmap_kiobuf() Benjamin C.R. LaHaise
2000-06-29 9:34 ` kmap_kiobuf() Stephen C. Tweedie
2000-06-29 13:45 ` kmap_kiobuf() Steve Lord
2000-06-28 16:52 kmap_kiobuf() lord
2000-06-28 18:06 ` kmap_kiobuf() Stephen C. Tweedie
2000-06-28 19:06 ` kmap_kiobuf() Manfred Spraul
2000-06-28 21:05 ` kmap_kiobuf() Andi Kleen
2000-06-28 15:41 kmap_kiobuf() David Woodhouse
2000-06-28 17:44 ` kmap_kiobuf() Stephen C. Tweedie
2000-06-29 10:52 ` kmap_kiobuf() Stephen C. Tweedie
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