Re: Memory Migration in Realtime Linux Kernels

--===============8259327214554660769==
Content-Type: multipart/alternative; boundary=00151747b8446b15ba04932571e9

--00151747b8446b15ba04932571e9
Content-Type: text/plain; charset=ISO-8859-1

Hi,

Sounds like you are talking about the feature to reduce memory latency on
NUMA which, if I'm not wrong, operates at lower level than shared memory
segments.  We have or will have the feature when OpenSSI is ported to a base
kernel with this feature.

Also the main feature of real-time Linux is reduced schedule latencies by
pre-empting more aggressively, not memory migration...

-Roger

On Thu, Oct 21, 2010 at 10:39 AM, Vincent Diepeveen <[email protected]> wrote:

> hi all,
>
> Maybe one of you knows as memory migration is hot of course for
> Single Image clusters; though it's off topic for SSIC,
> maybe i should subscribe again for linux-smp list.
>
> Apologies in advance for posting it here.
>
> Default linux kernel supports memory migration since 2.6.16 kernel,
> but i wonder whether it supports it automatically as independant feature.
>
> I wonder whether at my 4 socket AMD 8356 2.3Ghz (barcelona core),
> by default linux can have a memory migration.
>
> So we had allocated 'shared' memory and written memory at socket 3 by core
> 15, now socket 0 core 1 writes at that same memory, does it get migrated
> now to socket 0 dimms?
>
> Does the realtime linux kernel have memory migration of such type by
> default, if so when does it get triggered and when not?
>
> So i'm speaking about general memory migration, not migration of memory
> when also the proces/thread migrates to another core.
>
> If it does have it by default, does it also migrate when using
> shared memory (shmget + shmat), which is what i use in my chessprogram.
>
> Thanks in advance for answerring,
> Vincent
>
>
>
>
> ------------------------------------------------------------------------------
> Nokia and AT&T present the 2010 Calling All Innovators-North America
> contest
> Create new apps & games for the Nokia N8 for consumers in  U.S. and Canada
> $10 million total in prizes - $4M cash, 500 devices, nearly $6M in
> marketing
> Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store
> http://p.sf.net/sfu/nokia-dev2dev
> _______________________________________________
> Ssic-linux-users mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/ssic-linux-users
>

--00151747b8446b15ba04932571e9
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

Hi,<br><br>Sounds like you are talking about the feature to reduce memory l=
atency on NUMA which, if I&#39;m not wrong, operates at lower level than sh=
ared memory segments.=A0 We have or will have the feature when OpenSSI is p=
orted to a base kernel with this feature.<br>
<br>Also the main feature of real-time Linux is reduced schedule latencies =
by pre-empting more aggressively, not memory migration...<br><br>-Roger<br>=
<br><div class=3D"gmail_quote">On Thu, Oct 21, 2010 at 10:39 AM, Vincent Di=
epeveen <span dir=3D"ltr">&lt;<a href=3D"mailto:[email protected]">diep@xs4all=
.nl</a>&gt;</span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin: 0pt 0pt 0pt 0.8ex; borde=
r-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">hi all,<br>
<br>
Maybe one of you knows as memory migration is hot of course for<br>
Single Image clusters; though it&#39;s off topic for SSIC,<br>
maybe i should subscribe again for linux-smp list.<br>
<br>
Apologies in advance for posting it here.<br>
<br>
Default linux kernel supports memory migration since 2.6.16 kernel,<br>
but i wonder whether it supports it automatically as independant feature.<b=
r>
<br>
I wonder whether at my 4 socket AMD 8356 2.3Ghz (barcelona core),<br>
by default linux can have a memory migration.<br>
<br>
So we had allocated &#39;shared&#39; memory and written memory at socket 3 =
by core<br>
15, now socket 0 core 1 writes at that same memory, does it get migrated<br=
>
now to socket 0 dimms?<br>
<br>
Does the realtime linux kernel have memory migration of such type by<br>
default, if so when does it get triggered and when not?<br>
<br>
So i&#39;m speaking about general memory migration, not migration of memory=
<br>
when also the proces/thread migrates to another core.<br>
<br>
If it does have it by default, does it also migrate when using<br>
shared memory (shmget + shmat), which is what i use in my chessprogram.<br>
<br>
Thanks in advance for answerring,<br>
Vincent<br>
<br>
<br>
<br>
---------------------------------------------------------------------------=
---<br>
Nokia and AT&amp;T present the 2010 Calling All Innovators-North America co=
ntest<br>
Create new apps &amp; games for the Nokia N8 for consumers in =A0U.S. and C=
anada<br>
$10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketin=
g<br>
Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store<br=
>
<a href=3D"http://p.sf.net/sfu/nokia-dev2dev" target=3D"_blank">http://p.sf=
.net/sfu/nokia-dev2dev</a><br>
_______________________________________________<br>
Ssic-linux-users mailing list<br>
<a href=3D"mailto:[email protected]">Ssic-linux-users@=
lists.sourceforge.net</a><br>
<a href=3D"https://lists.sourceforge.net/lists/listinfo/ssic-linux-users" t=
arget=3D"_blank">https://lists.sourceforge.net/lists/listinfo/ssic-linux-us=
ers</a><br>
</blockquote></div><br>

--00151747b8446b15ba04932571e9--


--===============8259327214554660769==
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

------------------------------------------------------------------------------
Nokia and AT&T present the 2010 Calling All Innovators-North America contest
Create new apps & games for the Nokia N8 for consumers in  U.S. and Canada
$10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing
Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store 
http://p.sf.net/sfu/nokia-dev2dev
--===============8259327214554660769==
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

_______________________________________________
Ssic-linux-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/ssic-linux-users

--===============8259327214554660769==--