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[Libvir] CPU pinning of domains at creation time
by Daniel Veillard 18 Oct '07

18 Oct '07

There are a few things I gathered on this issue. This affects NUMA setups, where basically if a domain must be placed on a given cell it is not good to let the hypervisor place it first with its own heuristics and then later migrate it to a different set of CPU, but better to instruct the hypervisor to start said domain on the given set. - For Xen it is possible to instruct the hypervisor by passing (cpus '2,3') in the SExpr where the argument is a list of the physical processors allowed - For KVM I think the standard way would be to select the cpuset using sched_setaffinity() between the fork of the current process and the exec of the qemu process - there is no need (from a NUMA perspective) to do fine grained allocation at that point, as long as the domain can be restricted to a given cell at startup, then if needed virDomainPinVcpu() can be used later to do more precise pinning in order to try to optimize placement - to be able to instruct the hypervisor at creation time adding the information in the domain XML description looks the more natural way (another option would be to force to use virDomainDefineXML, add a call using the resulting virDomainPtr to define the set, and then virDomainCreate would be used to do the actual start) + the good point of having this embedded in the XML is that we still have all informations about the domain settings in the XML, if we want to restart it later + the bad point is that we need to fetch and carry this extra information when doing XML dumps to not loose it for example when manipulating the domain to add or remove devices - extracting a cpuset can still be an heavy operation, for example if using xend on need one RPC per vcpu in the domain, the cpuset being constructed by OR'ing logically all cpumaps used by the vcpus of the domain (though in most case this will be the full map after the first CPU and can be stopped immediately) - for the mapping at the XML level I suggest to use a simple extension to the <vcpu>n</vcpu> and extend it to <vcpu cpuset='2,3'>n</vcpu> with a limited syntax which is just the comma separated list of allowed CPU numbers (if the code actually detects such a cpuset is in effect i.e. in general this won't be added). Internally implementing this should not be too hard, I would probably refactor some of the existing parsing code, provide functions to get the cpuset and the number of physical processors. Does this sounds okay ? Daniel -- Red Hat Virtualization group http://redhat.com/virtualization/ Daniel Veillard | virtualization library http://libvirt.org/ veillard(a)redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/ http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/

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[Libvir] Problem to compile virt-manager in debian etch
by Marco Sinhoreli 18 Oct '07

18 Oct '07

Hello all, I have a problem to compile the virt-manager in a Debian etch (64 bit version). I got the virt-manager source from mercurial repository. Bellow the output autogen.sh command: ./autogen.sh libtoolize: `config.guess' exists: use `--force' to overwrite libtoolize: `config.sub' exists: use `--force' to overwrite libtoolize: `ltmain.sh' exists: use `--force' to overwrite configure.ac:7: required file `./config.rpath' not found man/Makefile.am:6: `%'-style pattern rules are a GNU make extension pixmaps/Makefile.am:3: wildcard $(srcdir: non-POSIX variable name pixmaps/Makefile.am:3: (probably a GNU make extension) src/Makefile.am:15: wildcard $(srcdir: non-POSIX variable name src/Makefile.am:15: (probably a GNU make extension) src/Makefile.am:35: `%'-style pattern rules are a GNU make extension src/Makefile.am:38: `%'-style pattern rules are a GNU make extension src/Makefile.am:41: `%'-style pattern rules are a GNU make extension src/Makefile.am:44: `%'-style pattern rules are a GNU make extension src/Makefile.am:26: variable `schema_SOURCES' is defined but no program or src/Makefile.am:26: library has `schema' as canonic name (possible typo) src/Makefile.am:11: variable `libexec_SOURCES' is defined but no program or src/Makefile.am:11: library has `libexec' as canonic name (possible typo) src/Makefile.am:4: variable `bin_SOURCES' is defined but no program or src/Makefile.am:4: library has `bin' as canonic name (possible typo) src/Makefile.am:18: variable `desktop_SOURCES' is defined but no program or src/Makefile.am:18: library has `desktop' as canonic name (possible typo) src/Makefile.am:8: variable `python_SOURCES' is defined but no program or src/Makefile.am:8: library has `python' as canonic name (possible typo) src/Makefile.am:22: variable `dbus_SOURCES' is defined but no program or src/Makefile.am:22: library has `dbus' as canonic name (possible typo) src/graphWidgets/Makefile.am:5: `:='-style assignments are not portable src/graphWidgets/Makefile.am:5: shell pkg-config --variable=codegendir pygtk-2.0: non-POSIX variable name src/graphWidgets/Makefile.am:5: (probably a GNU make extension) src/graphWidgets/Makefile.am:6: `:='-style assignments are not portable src/graphWidgets/Makefile.am:6: shell pkg-config --variable=defsdir pygtk-2.0: non-POSIX variable name src/graphWidgets/Makefile.am:6: (probably a GNU make extension) src/virtManager/Makefile.am:3: wildcard $(srcdir: non-POSIX variable name src/virtManager/Makefile.am:3: (probably a GNU make extension) src/virtManager/Makefile.am:7: python_DATA:$(srcdir: non-POSIX variable name src/virtManager/Makefile.am:15: `%'-style pattern rules are a GNU make extension Any idea? regards. -- Marco Sinhoreli

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[Libvir] PATCH: Remote protocol receive+dispatch cleanup
by Daniel P. Berrange 18 Oct '07

18 Oct '07

Dating the from time when we had both the QEMU & generic remote protocol there are tiny qemud/protocol.{x,c,h} files basically just containing one struct for the packet header. This is more or less duplicated in the remote protocol & with a few small tweaks can simplify this code. So the attached patch removes the protocol.{x,c,h} files. The qemud.c file in the 'receive header' branch now merely reads a single 4 byte unsigned int to discover the packet length. The rest of the packet is dealt with in the 'receive payload' branch. It immediately dispatches to the remote program. There is no wire format change here - shouuld just be code cleanup a/qemud/protocol.c | 17 -------------- a/qemud/protocol.h | 39 -------------------------------- a/qemud/protocol.x | 40 --------------------------------- qemud/Makefile.am | 5 ---- qemud/internal.h | 1 qemud/qemud.c | 57 +++++++++++++++--------------------------------- qemud/remote.c | 2 - qemud/remote_protocol.h | 1 qemud/remote_protocol.x | 3 ++ src/Makefile.am | 1 10 files changed, 24 insertions(+), 142 deletions(-) Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|

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[Libvir] BuildRequires check
by Jim Meyering 17 Oct '07

17 Oct '07

Hi, I tried to configure libvirt from cvs on a just-built rawhide system and it failed like this, since I hadn't installed the "check" package, which defines PKG_CHECK_EXISTS: checking for init script flavor... redhat checking for iptables... /sbin/iptables ./configure: line 12187: syntax error near unexpected token `libxml-2.0,LIBXML_FOUND=yes' ./configure: line 12187: ` PKG_CHECK_EXISTS(libxml-2.0,LIBXML_FOUND=yes)' Here's a fix: 2007-10-17 Jim Meyering <meyering(a)redhat.com> * libvirt.spec.in (BuildRequires): Add "check". Index: libvirt.spec.in =================================================================== RCS file: /data/cvs/libvirt/libvirt.spec.in,v retrieving revision 1.65 diff -u -p -r1.65 libvirt.spec.in --- libvirt.spec.in 12 Oct 2007 19:54:15 -0000 1.65 +++ libvirt.spec.in 17 Oct 2007 10:03:22 -0000 @@ -16,6 +16,7 @@ Requires: ncurses Requires: dnsmasq Requires: bridge-utils Requires: iptables +BuildRequires: check BuildRequires: xen-devel BuildRequires: libxml2-devel BuildRequires: readline-devel

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[Libvir] "make check" requires qemu
by Jim Meyering 17 Oct '07

17 Oct '07

So perhaps libvirt should BuildRequire qemu, too? When I ran "make check" on a system without qemu, I got lots of failures: ... QEMU XML-2-ARGV Misc ACPI ... FAILED libvir: QEMU error : Cannot find QEMU binary /usr/bin/qemu: No such file or directory QEMU XML-2-ARGV Misc No Reboot ... FAILED libvir: QEMU error : Cannot find QEMU binary /usr/bin/qemu: No such file or directory QEMU XML-2-ARGV Net User ... FAILED FAIL: qemuxml2argvtest Here's a patch: 2007-10-17 Jim Meyering <meyering(a)redhat.com> * libvirt.spec.in (BuildRequires): Add "qemu". Index: libvirt.spec.in =================================================================== RCS file: /data/cvs/libvirt/libvirt.spec.in,v retrieving revision 1.65 diff -u -p -r1.65 libvirt.spec.in --- libvirt.spec.in 12 Oct 2007 19:54:15 -0000 1.65 +++ libvirt.spec.in 17 Oct 2007 10:11:33 -0000 @@ -25,6 +25,7 @@ BuildRequires: gnutls-devel BuildRequires: avahi-devel BuildRequires: dnsmasq BuildRequires: bridge-utils +BuildRequires: qemu Obsoletes: libvir ExclusiveArch: i386 x86_64 ia64

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[Libvir] sexpr_get: add __printf__ attribute
by Jim Meyering 17 Oct '07

17 Oct '07

I noticed sexpr_get takes a printf-style format, yet it is declared with no printf attribute. Here's the fix: 2007-10-17 Jim Meyering <meyering(a)redhat.com> * src/xend_internal.c (sexpr_get): Declare with gcc's printf attribute. Index: src/xend_internal.c =================================================================== RCS file: /data/cvs/libvirt/src/xend_internal.c,v retrieving revision 1.148 diff -u -p -r1.148 xend_internal.c --- src/xend_internal.c 15 Oct 2007 21:38:56 -0000 1.148 +++ src/xend_internal.c 17 Oct 2007 08:29:26 -0000 @@ -692,6 +692,10 @@ xend_op(virConnectPtr xend, const char * */ static struct sexpr * sexpr_get(virConnectPtr xend, const char *fmt, ...) + __attribute__ ((__format__ (__printf__, 2, 3))); + +static struct sexpr * +sexpr_get(virConnectPtr xend, const char *fmt, ...) { char buffer[4096]; char path[1024];

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[Libvir] FYI: bug in remote code
by Mark Johnson 16 Oct '07

16 Oct '07

I ran into a bug in the remote code... I was doing # virsh -c xen_tcp://<ip_addr>/ It you don't have qemu compiled in, you will hang in in libvirtd in do_open() res = virNetworkDriverTab[i]->open (ret, name, flags); when trying to open the remote network driver. Usually qemu returns success and you fall out of the loop before you call this (which is why you won't see it with qemu support built in). You hang in libvirtd trying to read from the libvirtd PF_UNIX socket. You read from the socket because you hit this code path in doRemoteOpen() if (!uri->server && !transport_str) { if (flags & VIR_DRV_OPEN_REMOTE_UNIX) { transport = trans_unix; No idea what it should be doing? :-) I reproduced it on todays CVS bits on FC7 by commenting out qemu's network register.. int qemudRegister(void) { virRegisterDriver(&qemuDriver); /* virRegisterNetworkDriver(&qemuNetworkDriver); */ virRegisterStateDriver(&qemuStateDriver); return 0; } MRJ

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[Libvir] [for discussion only] virDomainBlockPeek preliminary implementation
by Richard W.M. Jones 16 Oct '07

16 Oct '07

The attached patch (for discussion only) adds a virDomainBlockPeek call, allowing callers to peek into the block devices of domains. +/** + * virDomainBlockPeek: + * @dom: pointer to the domain object + * @path: path to the block device + * @offset: offset within block device + * @size: size to read + * @buffer: return buffer (must be at least size bytes) + * + * This function allows you to read the contents of a domain's + * disk device. + * + * Typical uses for this are to determine if the domain has + * written a Master Boot Record (indicating that the domain + * has completed installation), or to try to work out the state + * of the domain's filesystems. + * + * (Note that in the local case you might try to open the + * block device or file directly, but that won't work in the + * remote case, nor if you don't have sufficient permission. + * Hence the need for this call). + * + * 'path' must be a device or file corresponding to the domain. + * In other words it must be the precise string returned in + * a <disk><source dev='...'/></disk> from + * virDomainGetXMLDesc. + * + * 'offset' and 'size' represent an area which must lie entirely + * within the device or file. 'size' may be 0 to test if the + * call would succeed. + * + * 'buffer' is the return buffer and must be at least 'size' bytes. + * + * Returns: 0 in case of success or -1 in case of failure. + */ +int +virDomainBlockPeek (virDomainPtr dom, + const char *path, + long long offset /* really 64 bits */, + size_t size, + void *buffer) The patch doesn't include: - remote - qemu - Xen < 3.0.3 inactive domains I will add these if I get favourable feedback. Rich. -- Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/ Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903

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[Libvir] PATCH: Implement CDROM media change for QEMU/KVM driver
by Daniel P. Berrange 16 Oct '07

16 Oct '07

Hugh recently added support for CDROM media change to the Xen driver, so I thought it was time I did the same for the QEMU/KVM driver. The attached patch implements the virDomainAttachDevice API to support changing the media of the CDROM device. To re-use the existing QEMU code for parsing I had to re-factor a couple of the internal QEMU device parsing apis so that they get supplied with a pre-allocated struct for the device info, rather than allocating it themselves. Although this isn't strictly needed for CDROM media change, I have prepared the virDomainAttachDevice method so that I can easily add USB device hotplut in the near future. It will also be useful when KVM gets paravirt driver support sooon... The actual implementation just runs the 'change cdrom path' command over the QEMU monitor console. diffstat libvirt-qemu-cdrom-change.patch qemu_conf.c | 135 +++++++++++++++++++++++++++++++++++++++------------------- qemu_conf.h | 21 +++++++++ qemu_driver.c | 132 ++++++++++++++++++++++++++++++++++++++++++++++++++------ 3 files changed, 230 insertions(+), 58 deletions(-) Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|

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[Libvir] Thoughts on remote storage support
by Tóth István 16 Oct '07

16 Oct '07

Hello! I had a hobby project where I needed to manipulate xen disk images on remote systems, that used a model similar to libirt's remote support. Based on what I learnt from it, I came up with a possible model for libvirt's remote storage support. I present it here for discussion. We typically store the images in volumes on LVM, or in dedicated file system folders. The folders and volume groups usable by libvirt can be limited in a config file. It is probably not neccessary to differentiate between defined and created files, as you can not stop and start a file like a domain, you either have it on disk, or not. Libvirt should not store information on these files, everything should be checked/listed on the fly, so that if you just copy an image to a directory, libvirt can deduct all information (well, all it can) on it, and handle it just as if the file was created by it. The handle for the file is its path, plus its virConnect object (i.e. the host it is on). For consistency, it may be possible to create an object for it, but as disk images have no persistent properties apart from what is on the disk, and it can always be checked from there, it provides no extra functionality. I think there is no need to support remote files explicitly, as the domains mount local files/volumes. The file/volume may actually be mounted from a NAS or SAN, of course, but it does not matter because we use the local path names, and AFAIK all virtualization tools use local files or local devices as blockdevs. I have added compression to the mix because it is immensely useful. I have used lzop in my project, and a full backup and restore was much faster when using a compressed backup file, than with and uncrompessed one. It conserves disk space, as well as cpu/bus capacity. Zeroing out newly allocated files, helps with compressed backups, as well as security. It also means that no holey files can be used. The objects we are dealing with are disk images. They have the following properties: -Path: The unix path of the file ( /mnt/images/fc7.img or /dev/VG/fc7) -Compression: Mountable/compressed -Type: Plain file/LVM volume/ What else? -Size -Filesystem: swap/ext3/xfs/.... -Is it mounted? We can do the following operations on the images: Create -connection -filepath -size Allocates a new image of the given type, size, and name. Libvirt should parse the filepath, and determine the base path, check if it's a directory or a VG, check if libvirt is allowed to operate on the path/VG, then create the file/volume. For security reasons zeroing out the allocated space should be a non-optional step of the allocation. DirectoryList -connection -directorypath Plain ls functionality, that returns the list of files, and any subdirectories. If called on a VG, it returns the volumes in it. Info -connection -filepath Returns information on the given file/volume, including size, type, filesystem (if available), whether it is a snapshot (if a volume), and whether it is mounted or not. size can be determined by ls or lvinfo, filesystem by 'file' command. Delete -connection -filepath Delete the file/volume. Find out if it's a file or volume, and rm or lvremove it. Grow -connection -path -filename -newsize Grows the specified image to the given size. The newly added space is zeroed out. Shrink? -connection -path -filename -newsize Shrinks the specified image the the given size. It's very tricky, because to avoid data loss, we need to analyze the file system size. Of course, we can just say that it's the reponsibility of the user, after all, we allow him to outright delete the file as well. We may combine it with Grow, and call it Resize. Growfs -connection -path -filename -newsize? Grows the filesystem on the image to fill the size of the image, or the given newsize. Can only be used on umounted images. It is neccesary because some filesystems may not be grown while mounted, so the guest can not do it on its own. Shrinkfs -connection -path -filname -newsize Shrinks the filesystem to the given size. Same coniderations apply as with growfs, may be combined to Resizefs? Snapshot -connection -filepath -filesize Creates a snapshot of the given image. It is only possible with images on LVM. Should return the snapshot image name. The snapshot can later be deleted with Delete. CopyTo -connection -source filepath -target connection -target filepath -snapshot flag -archive flag -overwrite flag Copy the source image to the target image. If connection is on another machine, then it's a network copy. If the snapshot flag is true, then first create a snapshot of the source image, copy that, then delete the snapshot. If the archive flag is active, then the target file will be archive file (compressed). If the overwite flag is active, then the target file is overwitten, if it exists. Otherwise existing files are not changed. Even if the source file is compressed, the target file is uncompressed, unless the archive flag is set. CopyContents -connection -source filepath -target connection -target filepath -snapshot flag Copies the contents of the source file to the target file. The target file must already exist, and be no smaller than the source file. The contents of the target file are overwitten, and any extra space is zeroed out. Archive -connection -filepath compresses the given file. Makes sense only on files, not volumes. Unarchive -connection -filepath uncompresses the given file. Makes sense only on archved(compressed) files. StorageInfo - connection Returns information on the node's storage configuration. What kind of filesystems it can handle, What are the accessible file / VG paths, what's the free space on them, etc. A typical usage scenario could be something like this: Aconn=getVirconn("ssh:Ahost"); //Open the connection to host A Bconn=getVirconn("ssh:Bhost"); //Host B will hold our backup image Ainfo=StorageInfo(Aconn); //Get Ainfo AVGPath = <get the first usable VG path from VG info> Newimage = Create(Aconn, concat("AVGPath", "newimage", 100000); //A 100Mb volume is created and zeroed out. CopyContents(Aconn, NewImage, Aconn, "/images/ghost/FC7default.img", no); //Copy our pre-created FC7 image to the new image Growfs(Aconn, NewImage, 0); //Grow the copied filesystem to fill the whole volume. <Here we define a new domain, and use NewImage as the name of the backing image for the guest's block device> <Start the new domain> Copy(Aconn, NewImage, Bconn, "/mnt/backups/backup23image", snapshot=yes, archive=yes, overwrite=no); //Make an LVM snapshot of NewImage, and copy it to Host B on the given filename, compressing it on the fly, then remove the snapshot <Stop the domain> CopyContents(Bconn, "/mnt/backups/backup23image", Aconn, NewImage, snapshot=no); //Restore the backed-up image to NewImage, decompress it on the fly. <Start the domain> <Stop the domain> Grow(Aconn, NewImage, 200000); //Grow the volume to 200MBs Growfs(Aconn, NewImage); //Grow the fs on the volume to fill the volume <Start the domain> ..... Best regards István

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