From: Benjamin LaHaise <bcrl@redhat.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Tony.P.Lee@nokia.com, linux-kernel@vger.kernel.org
Subject: Re: mprotect() api overhead.
Date: Sun, 24 Mar 2002 23:19:29 -0500 [thread overview]
Message-ID: <20020324231928.A20764@redhat.com> (raw)
In-Reply-To: <4D7B558499107545BB45044C63822DDE3A2047@mvebe001.NOE.Nokia.com> <E16ob93-00019V-00@the-village.bc.nu>
On Sat, Mar 23, 2002 at 02:20:37AM +0000, Alan Cox wrote:
> > As for SMP case, for my application, it is less an issue, since
> > when user call my API in the .so, the mprotect (or that HP=20
> > 7 instructions) will open access to the share memory for them
> > regardless which CPU they are coming from. If other thread
>
> That still requires cross processor synchronization - so it will still
> take the same hit
It's actually an instruction on ia64, so the overhead is fairly low
(similar to a cache miss). That said, Linux doesn't have the ability
to share portions of page tables between processes at present, so it
doesn't matter.
-ben
next prev parent reply other threads:[~2002-03-25 4:19 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-03-23 1:59 mprotect() api overhead Tony.P.Lee
2002-03-23 2:20 ` Alan Cox
2002-03-25 4:19 ` Benjamin LaHaise [this message]
-- strict thread matches above, loose matches on Subject: below --
2002-04-06 4:13 Pete Zaitcev
2002-03-22 23:09 Tony.P.Lee
2002-03-22 22:10 Tony.P.Lee
2002-03-22 22:57 ` Andrew Morton
2002-03-23 1:03 ` Alan Cox
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