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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-users] How To Pin domU VCPU To Specific CPU During Instance Creation
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 _______________________________________________ Xen-users mailing list Xen-users@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-users
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