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From: Gerd Hoffmann <kraxel@suse.de>
To: Ian Pratt <m+Ian.Pratt@cl.cam.ac.uk>
Cc: Andrew Theurer <habanero@us.ibm.com>, xen-devel@lists.xensource.com
Subject: Re: [PATCH] turn off writable page tables
Date: Wed, 26 Jul 2006 10:18:03 +0200	[thread overview]
Message-ID: <44C7253B.9080906@suse.de> (raw)
In-Reply-To: <A95E2296287EAD4EB592B5DEEFCE0E9D572236@liverpoolst.ad.cl.cam.ac.uk>

  Hi,

> I'd like to make sure there's no 'dumb stuff' happening, and the
> writeable pagetables isn't being used erroneously where we don't expect
> it (hence crippling the scores), and that its actually functioning as
> intended i.e. that we get one fault to unhook, and then a fault causing
> a rehook once we move to the next page in the fork.
>    
> If you write a little test program that dirties a large chunk of memory
> just before the fork, we should see writeable pagetables winning easily.

Just an idea:  Any chance mm_pin() and mm_unpin() cause this?  The bulk
page table updates for the new process created by fork() are not seen by
xen anyway I think.  The first schedule of the new process triggers
pinning, i.e. r/o mapping and verification ...

cheers,

  Gerd

-- 
Gerd Hoffmann <kraxel@suse.de>
http://www.suse.de/~kraxel/julika-dora.jpeg

  parent reply	other threads:[~2006-07-26  8:18 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-07-25 22:41 [PATCH] turn off writable page tables Ian Pratt
2006-07-26  2:25 ` Andrew Theurer
2006-07-26  5:31   ` Jacob Gorm Hansen
2006-07-26  8:18 ` Gerd Hoffmann [this message]
2006-07-26  8:40   ` Keir Fraser
2006-07-26 21:10     ` Andrew Theurer
  -- strict thread matches above, loose matches on Subject: below --
2006-07-28 15:51 Ian Pratt
2006-07-28 16:31 ` Keir Fraser
2006-07-28 21:36   ` Zachary Amsden
2006-07-28 23:05     ` Andi Kleen
2006-07-28 23:10       ` Zachary Amsden
2006-07-31  9:14         ` Keir Fraser
2006-07-31  9:32           ` Zachary Amsden
2006-07-31  9:53             ` Keir Fraser
2006-07-31 19:56               ` Zachary Amsden
2006-07-31 22:07                 ` Keir Fraser
2006-07-31 22:40                   ` Zachary Amsden
2006-08-02  9:21                     ` Keir Fraser
2006-07-27 17:31 Ian Pratt
2006-07-28  8:55 ` Keir Fraser
2006-07-28 15:21   ` Andrew Theurer
     [not found] <E1G5sBV-0005eg-At@host-192-168-0-1-bcn-london>
2006-07-26 23:38 ` Joe Bonasera
2006-07-26 21:38 Ian Pratt
2006-07-27 14:43 ` Andrew Theurer
2006-07-27 15:30   ` Keir Fraser
2006-07-25 22:14 Andrew Theurer
2006-07-25 22:43 ` Nivedita Singhvi
2006-07-25 23:19   ` Andrew Theurer

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