On Sun, Aug 30, 2009 at 3:43 AM, Peter Teoh <htmldeveloper@xxxxxxxxx> wrote:
you dont need to do that everytime ... think hashes...
and only if they match go ahead compare byte-by-byte
cow it is.
Thank you Minchan. You made me curious now...:-).
Have not really pursued deeply other than:
On Sat, Aug 29, 2009 at 9:37 PM, Minchan Kim<minchan.kim@xxxxxxxxx> wrote:
> Hi, Peter.
>
> On Sun, Aug 30, 2009 at 9:20 AM, Peter Teoh<htmldeveloper@xxxxxxxxx> wrote:
>> The papers are located here:
>>
>> http://www.linuxsymposium.org/2009/ls-2009-proceedings.pdf
>>
>> I have not read any papers yet. But given limited amount of time -
>> which papers do u think are the interesting one to read? And perhaps
>
> In my case, I will take a "Increasing memory density by using KSM".
>
http://lkml.org/lkml/2009/4/19/210
But conceptually:
a. what is the criteria of deciding when two piece of memory are
identical? (if it is byte-for-byte comparison then performance will
be seriously disastrous?)
you dont need to do that everytime ... think hashes...
and only if they match go ahead compare byte-by-byte
b. and after memory memory coalescing....due to "identical" memory -
necessarily this is applicable to read-only memory right? (if not
then it may be modified later....and u need to trigger copy-on-write
mechanism to duplicate the memory piece....lots of overheads i
supposed).
cow it is.
c. but isn't it very dangerous - even though it is read-only....one
KVM client can actually modify the memory (just set_memory_rw() to
turn it read-write, and then write to it.....and effectly the entire
chain of KVM effectively is compromised via having a corrupted piece
of memory? but then again i am suspecting i am completely
wrong.....as logically KVM client should not be able to change
memory's PTE attribute just purely using set_memory_rw() as a VM
client. if this is true, then it means that u need duplication of
the pagetables to describes the memory attributes - one for the VM
client, and one for the VM host? Sorry....completely newbie...
d. on the other hand....if it is really permanently set to
readonly....and a KVM client after calling set_memory_rw()...still
will NOT be able to set the memory read-write....then immediately the
KVM client can deduce something about the server....eg....VM
environment...as real x86 hardware does not have memory readonly
setting capability...
Thank you for the sharing....
>> one-liners comment on why?
>
> There is no special reason. If I have to say,
>
> 1. I have a interesting in mm,
> 2, KSM is one of hot topics these days.
> 3. KSM can affect both server and embedded device
> 4. I know authour's many contiribution in linux kernel so that I don't
> doubt paper's quality.
>
> :)
--
Regards,
Peter Teoh
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