No problem. I'll give it some more time here and then follow-up with the devel
list.
Thank you,
Adrian
Todd Deshane wrote:
>
>
> On Tue, Jul 8, 2008 at 10:47 AM, Adrian Turcu <adriant@xxxxxxxxxx
> <mailto:adriant@xxxxxxxxxx>> wrote:
>
> Thanks for the quick reply Todd, but I guess my problem is not to
> exclude certain CPUs to be used by the guests,
> but to pin down VCPUs to specific CPUs when using a list.
> Take this one for example on my config:
>
> ### shared-smq6
> cpus = "1,2"
> vcpus = 2
>
> That means, I use a circular list of CPU 1 and CPU 2, and 2 VCPUs
> which can pick any from the list.
> This is true as per output of "xm vcpu-list shared-smq6" command:
>
> Name ID VCPU CPU State Time(s) CPU
> Affinity
> shared-smq6 5 0 1 -b- 21713.0 1-2
> shared-smq6 5 1 1 -b- 31214.3 1-2
>
> What I would like is to be able to say in the config file directly,
> i.e. "use CPU 1 for VCPU 0 and CPU 2 for VCPU 1"
> At the moment I can do that only by using "xm vcpu-pin" command.
>
> If that is already in those threads, I cannot see it to be honest.
> Could you just sent the kind of config you envisage by using ^ ?
>
>
> I actually don't have a lot of personal experience with vcpu pinning.
>
> That thread I gave you was the first time I saw the syntax for it.
>
> Any thoughts or experiences from others?
>
> If after a day or two on the users list and no response/no solutions.
> Feel free to post a fresh post to xen-devel with all the details of what
> you have tried, what works etc.
>
> If it was me, I would try to read through the source code to find the
> answer. I can't commit to helping you with that today due to time
> constraints.
>
> Good luck.
>
> Best Regards,
> Todd
>
>
>
> Thank you,
> Adrian
>
>
> Todd Deshane wrote:
> >
> >
> > On Tue, Jul 8, 2008 at 6:54 AM, Adrian Turcu <adriant@xxxxxxxxxx
> <mailto:adriant@xxxxxxxxxx>
> > <mailto:adriant@xxxxxxxxxx <mailto:adriant@xxxxxxxxxx>>> wrote:
> >
> > Hi all
> >
> > I was browsing the archives to find a solution to my "problem" but
> > with no luck.
> > Here is the scenario:
> >
> > Host:
> > Hardware: Dell PE 1950, 4 x dual core CPU, 16GB RAM
> > OS: FC8, kernel 2.6.21-2950.fc8xen
> > Xen version: 3.1.0-rc7-2950.fc8
> >
> > Guests:
> > OS: FC8, kernel 2.6.21-2950.fc8xen
> >
> > I want to be able during guest instance creation to pin down
> each of
> > the VCPUs to specific CPU cores.
> > I can do that after the instance is up by using "xm vcpu-pin"
> > command, but I would love to be able to do it straight from the
> > config file.
> >
> >
> >
> > I would suggest this thread:
> >
>
> http://markmail.org/search/?q=xen-devel+ian+pratt+cpu+pin+syntax#query:xen-devel%20ian%20pratt%20cpu%20pin%20syntax+page:1+mid:2vlhnty3zemednba+state:results
> >
> > Take a look at the syntax with the ^
> >
> > Hope that helps,
> > Todd
> >
> >
> >
> >
> > two config files:
> >
> > ### shared-db4
> > kernel = "/boot/vmlinuz-2.6.21-2950.fc8xen"
> > ramdisk = "/boot/initrd-2.6.21-2950.fc8xen-domU.img"
> > name = "shared-db4"
> > memory = 8192
> > cpus = "4,5"
> > vcpus = 2
> > vif = [ 'mac=00:16:3E:13:02:01, bridge=br162',
> > 'mac=00:16:3E:13:04:01, bridge=br164' ]
> > disk = [
> >
>
> 'phy:disk/by-path/ip-nas01-681:3260-iscsi-iqn.2008-02.com.newbay.celerra.domu-root-lun-0-part1,hda1,r'
> > ,
> >
>
> 'phy:disk/by-path/ip-nas01-681:3260-iscsi-iqn.2008-02.com.newbay.celerra.domu-00163e130001-lun-0-part1,hdb1,w'
> > ,
> >
>
> 'phy:disk/by-path/ip-nas01-681:3260-iscsi-iqn.2008-02.com.newbay.celerra.domu-00163e130001-lun-1-part1,hdc1,w'
> > ,
> >
>
> 'phy:disk/by-path/ip-nas01-681:3260-iscsi-iqn.2008-02.com.newbay.celerra.domu-00163e130001-lun-2-part1,hdd1,w'
> > ]
> > root = "/dev/hda1 ro"
> > extra = "3 selinux=0 enforcing=0"
> > on_poweroff = 'destroy'
> > on_reboot = 'restart'
> > on_crash = 'restart'
> >
> >
> >
> > ### shared-smq6
> > kernel = "/boot/vmlinuz-2.6.21-2950.fc8xen"
> > ramdisk = "/boot/initrd-2.6.21-2950.fc8xen-domU.img"
> > name = "shared-smq6"
> > memory = 2560
> > cpus = "1,2"
> > vcpus = 2
> > vif = [ 'mac=00:16:3E:13:03:03, bridge=br163' ]
> > disk = [
> >
>
> 'phy:disk/by-path/ip-nas01-681:3260-iscsi-iqn.2008-02.com.newbay.celerra.domu-root-lun-0-part1,hda1,r'
> > ,
> >
>
> 'phy:disk/by-path/ip-nas01-681:3260-iscsi-iqn.2008-02.com.newbay.celerra.domu-00163e130003-lun-0-part1,hdb1,w'
> > ,
> >
>
> 'phy:disk/by-path/ip-nas01-681:3260-iscsi-iqn.2008-02.com.newbay.celerra.domu-00163e130003-lun-1-part1,hdc1,w'
> > ,
> >
>
> 'phy:disk/by-path/ip-nas01-681:3260-iscsi-iqn.2008-02.com.newbay.celerra.domu-00163e130003-lun-2-part1,hdd1,w'
> > ]
> > root = "/dev/hda1 ro"
> > extra = "3 selinux=0 enforcing=0"
> > on_poweroff = 'destroy'
> > on_reboot = 'restart'
> > on_crash = 'restart'
> >
> >
> > "xm vcpu-list" output:
> > Name ID VCPU CPU State
> Time(s) CPU
> > Affinity
> > Domain-0 0 0 0 r--
> 118567.5 any cpu
> > Domain-0 0 1 - --p
> 2.9 any cpu
> > Domain-0 0 2 - --p
> 30.4 any cpu
> > Domain-0 0 3 - --p
> 2.2 any cpu
> > Domain-0 0 4 - --p
> 3.2 any cpu
> > Domain-0 0 5 - --p
> 2.0 any cpu
> > Domain-0 0 6 - --p
> 2.0 any cpu
> > Domain-0 0 7 - --p
> 3.8 any cpu
> > shared-db4 6 0 4 r-- 446383.3 4
> > shared-db4 6 1 5 -b- 89830.3 5
> > shared-smq4 2 0 6 -b-
> 53710.6 6-7
> > shared-smq4 2 1 6 -b-
> 87263.8 6-7
> > shared-smq6 5 0 1 -b-
> 21681.7 1-2
> > shared-smq6 5 1 1 -b-
> 31198.6 1-2
> >
> > shared-db4 was altered after instance creation by using "xm
> vcpu-pin
> > shared-db4 0 4 ; xm vcpu-pin shared-db4 1 5",
> > the rest of the guests are as they were created using "xm create
> > <config file>" command or automatically started at host reboot
> > (/etc/xen/auto folder).
> >
> > Don't know if this has an impact or not, but I am using sedf
> > scheduler and I have a cron job which sets weight=1 for all newly
> > created instances:
> > #!/bin/bash
> >
> > # change weigth to 1
> > /usr/sbin/xm sched-sedf | grep -v Name | tr -s ' ' | cut -d\
> -f7,1
> > | while read a b ; do if [ $b -eq 0 ] ; then /usr/sbin/xm
> sched-sedf
> > $a -w1 ; fi ; done
> >
> >
> > The reason:
> >
> > I can see in the guest domains a lot of percentage spent in "CPU
> > Steal" column
> > when the systems are under heavy CPU pressure.
> > Changing the CPU affinity on each VCPU seem to keep "CPU steal" in
> > the guests to almost 0 during similar system loads.
> >
> > I also came across this old article (maybe still valid):
> >
> > http://virt.kernelnewbies.org/ParavirtBenefits
> >
> > which in particular states:
> >
> > "The time spent waiting for a physical CPU is never billed
> against a
> > process,
> > allowing for accurate performance measurement even when there
> is CPU
> > time contention between *multiple virtual machines*.
> >
> > The amount of time the virtual machine slowed down due to such CPU
> > time contention is split out as so-called "steal time"
> > in /proc/stat and properly displayed in tools like vmstat(1),
> top(1)
> > and sar(1)."
> >
> > Is this because the CPU affinity is shared with Domain-0?
> > Maybe I am mixing stuff here, nevertheless, I'd like to be able to
> > pin each VCPU to a physical CPU core (if that makes sense).
> >
> >
> > Thank you in advance,
> > Adrian
> >
> >
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@xxxxxxxxxxxxxxxxxxx
> <mailto:Xen-users@xxxxxxxxxxxxxxxxxxx>
> <mailto:Xen-users@xxxxxxxxxxxxxxxxxxx
> <mailto:Xen-users@xxxxxxxxxxxxxxxxxxx>>
> > http://lists.xensource.com/xen-users
> >
> >
> >
> >
> > --
> > Todd Deshane
> > http://todddeshane.net
> > check out our book: http://runningxen.com
>
>
>
>
>
> --
> Todd Deshane
> http://todddeshane.net
> check out our book: http://runningxen.com
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