From mboxrd@z Thu Jan  1 00:00:00 1970
From: Anthony Liguori <anthony@codemonkey.ws>
Subject: Re: kvm userspace: ksm support
Date: Tue, 28 Jul 2009 20:27:18 -0500
Message-ID: <4A6FA576.6020806@codemonkey.ws>
References: <20090728193959.49cc28b6@woof.woof> <4A6F2A38.30500@codemonkey.ws> <4A6F2C59.8020306@redhat.com>
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Cc: kvm@vger.kernel.org, "Justin M. Forbes" <jforbes@redhat.com>,
	Mark McLoughlin <markmc@redhat.com>
To: Izik Eidus <ieidus@redhat.com>
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Izik Eidus wrote:
>
> You mean: when we later call for other madvise calls, if it will 
> remove the MADV_MERGEABLE from that memory?
> if yes, the answer is no, it should be still l left in the 
> vma->vm_flags...

Excellent.

>>
>> I'd suggest doing the following in osdep.h too:
>>
>> #if !defined(MADV_MERGABLE)
>> #define MADV_MERGABLE MADV_NORMAL
>> #endif
>>
>> To avoid #ifdefs in .c files.
>
> I tried to follow the way DONTFORK madvise is working...
>
> So you say, just to throw this thing into osdep.h instead of that c file?

Yes.

I think the DONTFORK thing is a bit odd.  Of course we have 
MADV_DONTFORK if we're running KVM.  I'm not sure why that is there.

I also think that we could get away with getting rid of any checks for 
!sync_mmu() since that was introduced in 2.6.27.

Otherwise, you should technically avoid doing madvise() unless we have 
sync_mmu().

Regards,

Anthony Liguori