Hi, I''m trying to figure out if blktap or qemu is the best backend for raw images? Using xen4.2 and kernel 3.2 and 3.5 theres a lot of problems with blktap, hacking blktap, hanging devices, unbootable domUs (block device errors). Performance in the qemu backend actually seems to be quite ok, 5-20% slower than LVM though - but not that much slower than blktap. It seems that a userspace blktap3 is not coming soon (http://lists.xen.org/archives/html/xen-devel/2012-04/msg00583.html) so maybe one should just settle with qemu for now. - Anybody know where the source code for blktap3 is? - xl top does not show VBD stats for qemu devices - is this expected? Thanks. Regards Kristoffer -- View this message in context: http://xen.1045712.n5.nabble.com/blktap-vs-qemu-backend-tp5710961.html Sent from the Xen - User mailing list archive at Nabble.com.
Hi Kristoffer ! Did you get a reply for this ? I am very interested in the future of the block device layer as well. Matthias>________________________________ > From: Kristoffer Harthing Egefelt <k@itoc.dk> >To: xen-users@lists.xensource.com >Sent: Tuesday, September 4, 2012 7:23 AM >Subject: [Xen-users] blktap vs qemu backend > >Hi, > >I''m trying to figure out if blktap or qemu is the best backend for raw >images? > >Using xen4.2 and kernel 3.2 and 3.5 theres a lot of problems with blktap, >hacking blktap, hanging devices, unbootable domUs (block device errors). > >Performance in the qemu backend actually seems to be quite ok, 5-20% slower >than LVM though - but not that much slower than blktap. > >It seems that a userspace blktap3 is not coming soon >(http://lists.xen.org/archives/html/xen-devel/2012-04/msg00583.html) so >maybe one should just settle with qemu for now. > >- Anybody know where the source code for blktap3 is? >- xl top does not show VBD stats for qemu devices - is this expected? > >Thanks. >Regards >Kristoffer > > > > >-- >View this message in context: http://xen.1045712.n5.nabble.com/blktap-vs-qemu-backend-tp5710961.html >Sent from the Xen - User mailing list archive at Nabble.com. > >_______________________________________________ >Xen-users mailing list >Xen-users@lists.xen.org >http://lists.xen.org/xen-users > > >_______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
No, but I found this: blktap-dkms v. 2.0.93 https://github.com/mcclurmc/blktap-dkms which compiles on kernel 3.5.3 and seems to work. Next issue is to get blktap from git://github.com/xen-org/blktap.git to compile and work with libxl. blktap compiles - but does not hook into xl, which makes xen use the "old" blktap. Any ideas on how to merge the new blktap (tap-ctl specifically) into xen 4.2? -- View this message in context: http://xen.1045712.n5.nabble.com/blktap-vs-qemu-backend-tp5710961p5711702.html Sent from the Xen - User mailing list archive at Nabble.com.
I''ve no idea whether blktap2 from github needs to hook into libxl, but I''d check to make sure whether the github blktap2 binaries do overwrite the Xen blktap2 ones. -- Thanos Makatos> -----Original Message----- > From: xen-users-bounces@lists.xen.org [mailto:xen-users- > bounces@lists.xen.org] On Behalf Of Kristoffer Harthing Egefelt > Sent: 03 October 2012 23:10 > To: xen-users@lists.xensource.com > Subject: Re: [Xen-users] blktap vs qemu backend > > No, but I found this: > > blktap-dkms v. 2.0.93 > https://github.com/mcclurmc/blktap-dkms > > which compiles on kernel 3.5.3 and seems to work. > > Next issue is to get blktap from > > git://github.com/xen-org/blktap.git > > to compile and work with libxl. > > blktap compiles - but does not hook into xl, which makes xen use the > "old" > blktap. > > Any ideas on how to merge the new blktap (tap-ctl specifically) into > xen 4.2? > > > > > -- > View this message in context: http://xen.1045712.n5.nabble.com/blktap- > vs-qemu-backend-tp5710961p5711702.html > Sent from the Xen - User mailing list archive at Nabble.com. > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xen.org > http://lists.xen.org/xen-users
I move blktap from github to tools/blktap2 with but I get the following error, which I think indicates that libxl needs something that blktap from github does not have? libxl_blktap2.c: In function ‘libxl__blktap_devpath’: libxl_blktap2.c:36:5: error: implicit declaration of function ‘tap_ctl_find’ [-Werror=implicit-function-declaration] libxl_blktap2.c:44:5: error: too few arguments to function ‘tap_ctl_create’ In file included from libxl_blktap2.c:18:0: /usr/src/xen-unstable.hg/tools/libxl/../../tools/blktap2/include/tap-ctl.h:98:5: note: declared here libxl_blktap2.c: In function ‘libxl__device_destroy_tapdisk’: libxl_blktap2.c:77:30: error: ‘tap_list_t’ has no member named ‘id’ libxl_blktap2.c:77:5: error: too few arguments to function ‘tap_ctl_destroy’ In file included from libxl_blktap2.c:18:0: /usr/src/xen-unstable.hg/tools/libxl/../../tools/blktap2/include/tap-ctl.h:100:5: note: declared here libxl_blktap2.c:79:9: error: ‘tap_list_t’ has no member named ‘id’ If I compile blktap from github separately it does not know about the devices xl creates... Any ideas ? :-) Thanks -- View this message in context: http://xen.1045712.n5.nabble.com/blktap-vs-qemu-backend-tp5710961p5711719.html Sent from the Xen - User mailing list archive at Nabble.com. _______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
On Thu, 2012-10-04 at 12:39 +0100, Kristoffer Harthing Egefelt wrote:> I move blktap from github to tools/blktap2 with but I get the following > error, which I think indicates that libxl needs something that blktap from > github does not have?IIRC there were some changes to the API but equivalent functionality should be present. You probably need to get out your coding gloves though I'm afraid.> > libxl_blktap2.c: In function ‘libxl__blktap_devpath’: > libxl_blktap2.c:36:5: error: implicit declaration of function ‘tap_ctl_find’ > [-Werror=implicit-function-declaration] > libxl_blktap2.c:44:5: error: too few arguments to function ‘tap_ctl_create’ > In file included from libxl_blktap2.c:18:0: > /usr/src/xen-unstable.hg/tools/libxl/../../tools/blktap2/include/tap-ctl.h:98:5: > note: declared here > libxl_blktap2.c: In function ‘libxl__device_destroy_tapdisk’: > libxl_blktap2.c:77:30: error: ‘tap_list_t’ has no member named ‘id’ > libxl_blktap2.c:77:5: error: too few arguments to function ‘tap_ctl_destroy’ > In file included from libxl_blktap2.c:18:0: > /usr/src/xen-unstable.hg/tools/libxl/../../tools/blktap2/include/tap-ctl.h:100:5: > note: declared here > libxl_blktap2.c:79:9: error: ‘tap_list_t’ has no member named ‘id’ > > If I compile blktap from github separately it does not know about the > devices xl creates... > > Any ideas ? :-) > > Thanks > > > > -- > View this message in context: http://xen.1045712.n5.nabble.com/blktap-vs-qemu-backend-tp5710961p5711719.html > Sent from the Xen - User mailing list archive at Nabble.com. > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xen.org > http://lists.xen.org/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
>You probably need to get out your coding gloves though I''m afraid.I will try and let you know ;-) but I''m wondering what the difference is between the two blktaps - why is xen not shipping with the blktap from github if it got more features? Could it be that some functionality will be missing from the github blktap if I just replace xen blktap utils? Thanks -- View this message in context: http://xen.1045712.n5.nabble.com/blktap-vs-qemu-backend-tp5710961p5711721.html Sent from the Xen - User mailing list archive at Nabble.com.
On Thu, 2012-10-04 at 12:54 +0100, Kristoffer Harthing Egefelt wrote:> >You probably need to get out your coding gloves though I''m afraid. > > I will try and let you know ;-) but I''m wondering what the difference is > between the two blktaps - why is xen not shipping with the blktap from > github if it got more features?The github one was a somewhat unintentional fork of the in-tree one by the XCP/XenServer folks and the in tree one has lagged somewhat. Thanos is working on resolving that fork as part of his blktap3 effort, which apart from taking the github stuff also removes the need for the kernel driver.> Could it be that some functionality will be missing from the github blktap > if I just replace xen blktap utils?If anything I would expect github to have more not less features. Ian.
Great - thanks - I''ll talk to Thanos. On 04/10/2012, at 14.07.00, Ian Campbell <Ian.Campbell@citrix.com> wrote:> On Thu, 2012-10-04 at 12:54 +0100, Kristoffer Harthing Egefelt wrote: >>> You probably need to get out your coding gloves though I''m afraid. >> >> I will try and let you know ;-) but I''m wondering what the difference is >> between the two blktaps - why is xen not shipping with the blktap from >> github if it got more features? > > The github one was a somewhat unintentional fork of the in-tree one by > the XCP/XenServer folks and the in tree one has lagged somewhat. > > Thanos is working on resolving that fork as part of his blktap3 effort, > which apart from taking the github stuff also removes the need for the > kernel driver. > >> Could it be that some functionality will be missing from the github blktap >> if I just replace xen blktap utils? > > If anything I would expect github to have more not less features. > > Ian. >