Hi folks, I compiled my dom0 kernel to support SMP on my dual PIII machine. Now I am not sure if it is used/usable. As far as I understood in xen stable a single dom (even dom0) cannot make use of multiple processors, but I can bind a dom to a certain CPU. But how can I check if SMP is successfully activated? dmesg in dom0 states "initializing CPU#0", but that is done on single processor machines also. Do I have to bind a domU to CPU#1 and see if it crashes? By the way, what is the exact syntax for binding to a certain CPU? Any hint or help or pointer to the right docs is welcome. Dirk _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Tuesday 01 November 2005 04:37, Dirk H. Schulz wrote:> But how can I check if SMP is successfully activated? ..."xm list" shows who''s running where> Do I have to bind a domU to CPU#1 and see if it crashes? > By the way, what is the exact syntax for binding to a certain CPU?In the guest config: "cpu=[CPU#]". If cpu=-1, Xen picks.> Any hint or help or pointer to the right docs is welcome.The example1.conf and example2.conf files have useful comments. http://www.cl.cam.ac.uk/Research/SRG/netos/xen/readmes/user/user.html#SECTION03210000000000000000 - -- pea 319E 1969 C476 E38D 6133 D3B4 6314 A6A9 67B6 ABB9 - --------------------------------- I''ll see it when I believe it. -Farberism #345 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.0 (GNU/Linux) iD8DBQFDZ63QYxSmqWe2q7kRAkUNAKCigf2+nNk8ZssbDyR6l1dlciEeXwCcCSir wujbp618WNEkYJywHtfNqQg=Qd8l -----END PGP SIGNATURE----- _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Dirk H. Schulz
2005-Nov-07 07:16 UTC
SMP does not work as expected - was: Re: [Xen-users] Checking for SMP usage in xen stable
Hi folks,
I looked somewhat deeper into the smp issue with Xen 2.0.7. I found that
smp is used even on machines with only one processor.
This is xm list on an IBM x335, a dual processor board with one processor:
Name Id Mem(MB) CPU State Time(s)
Console
Domain-0 0 123 0 r----
59931.7
webdynown01 5 511 1 -b---
193.5 9605
webstatown01 1 255 0 -b---
202.9 9601
I have configured CPU usage in the domU''s config files. So two of one
CPUs are used, it seems.
This is xm list on a single processor machine:
Name Id Mem(MB) CPU State
Time(s) Console
Domain-0 0 123 0
r---- 5567.2
sync01 2 95 0
-b--- 1.8 9602
So it seems that on dual processor boards smp is somehow simulated if
there is just one processor present.
Is this a bug, or does it make sense somehow?
And now my original question comes up again: How can I - reliably -
verify that my xen kernel is running smp code?
Dirk
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Dirk H. Schulz
2005-Nov-07 07:20 UTC
Re: SMP does not work as expected - was: Re: [Xen-users] Checking for SMP usage in xen stable
Seems like thunderbird does not like copying from a terminal window. I try it again: Dirk H. Schulz schrieb:> Hi folks, > > I looked somewhat deeper into the smp issue with Xen 2.0.7. I found > that smp is used even on machines with only one processor. > > This is xm list on an IBM x335, a dual processor board with one > processor: > > Name Id Mem(MB) CPU State Time(s) > Console > Domain-0 0 123 0 r---- > 59931.7> webdynown01 5 511 1 -b--- > 193.5 9605 > webstatown01 1 255 0 -b--- > 202.9 9601 > > I have configured CPU usage in the domU''s config files. So two of one > CPUs are used, it seems. > > This is xm list on a single processor machine: > > Name Id Mem(MB) CPU State > Time(s) Console > Domain-0 0 123 0 > r---- 5567.2> sync01 2 95 0 > -b--- 1.8 9602 > > So it seems that on dual processor boards smp is somehow simulated if > there is just one processor present. > > Is this a bug, or does it make sense somehow? > > And now my original question comes up again: How can I - reliably - > verify that my xen kernel is running smp code? > > Dirk > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Derrik Pates
2005-Nov-13 04:22 UTC
Re: SMP does not work as expected - was: Re: [Xen-users] Checking for SMP usage in xen stable
Dirk H. Schulz wrote:>> Name Id Mem(MB) CPU State Time(s) >> Console >> Domain-0 0 123 0 r---- >> 59931.7 > > >> webdynown01 5 511 1 -b--- >> 193.5 9605 >> webstatown01 1 255 0 -b--- >> 202.9 9601You have a Xeon, which supports hyperthreading, and Xen treats the hyperthreaded CPU as two virtual CPUs. That''s pretty much typical, and pretty much the way most OSes see a hyperthreaded CPU.>> So it seems that on dual processor boards smp is somehow simulated if >> there is just one processor present. >> >> Is this a bug, or does it make sense somehow?It''s not a bug. It does make perfect sense.>> And now my original question comes up again: How can I - reliably - >> verify that my xen kernel is running smp code?Run ''xm info'' and look at the ''cores'' and ''hyperthreads_per_core'' fields? If there are multiple physical CPUs (or in the case of e.g. a dual-core Opteron, you''ll see 2 cores for each CPU), and ''hyperthreads_per_core'' will be 2 on Xeon CPUs and HT-capable P4 CPUs (assuming you haven''t turned off hyperthreading in the BIOS, or passed arguments to Xen itself causing it to ignore the MP tables). -- Derrik Pates demon@devrandom.net _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users