This is an interesting interview with a VMware executive about Xen. One of his statements is that Xen is "purely for Linux." http://blogs.zdnet.com/BTL/index.php?p=1055 Tim ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
Typical corporate talking head blah. Interesting that he talks about Vmotion as a ''killer technology'' when Xen is already doing it. If you read the interview there''s quite a bit of Xen-bashing. The guy rags on the requirement for modification of the host kernel. He is comparing the two products as if they took the same approach, failing to mention that Xen''s paravirtualisation architecture eliminates all of the costly performance overhead his company''s product is famous for... -----Original Message----- From: xen-devel-admin@lists.sourceforge.net [mailto:xen-devel-admin@lists.sourceforge.net] On Behalf Of Tim Freeman Sent: Thursday, 17 February 2005 4:09 a.m. To: xen-devel@lists.sourceforge.net Subject: [Xen-devel] Xen and VMware This is an interesting interview with a VMware executive about Xen. One of his statements is that Xen is "purely for Linux." http://blogs.zdnet.com/BTL/index.php?p=1055 Tim ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_ide95&alloc_id396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
Tom Hibbert wrote:> Typical corporate talking head blah. Interesting that he talks about > Vmotion as a ''killer technology'' when Xen is already doing it. > If you read the interview there''s quite a bit of Xen-bashing. The guy > rags on the requirement for modification of the host kernel. He is > comparing the two products as if they took the same approach, failing to > mention that Xen''s paravirtualisation architecture eliminates all of the > costly performance overhead his company''s product is famous for...I still think you need to respect VMWare for breathing new life into virtual machine research. And I still think Xen can be improved (as is happening now) with regards to memory footprint etc. VMWare ESX is also likely to have some performance benefits from having the drivers in the kernel, even though that comes at the cost of them having to implement the drivers themselves. And the fact that they can host Windows is a big win with lots of customers. VMWare does some amount of paravirtualization, with all the VMWare tools that you need to install. In fact, Xen seems to be going in VMWare''s direction (shadow page tables, writable page tables, binary rewriting, Vanderpool support) in some areas. The fact that I seem to have prior art for their ''killer technology'' I just find kind of funny ;-) Jacob ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
On Wed, 16 Feb 2005 14:50:23 -0800, Jacob Gorm Hansen <jacobg@diku.dk> wrote:> Tom Hibbert wrote: > > Typical corporate talking head blah. Interesting that he talks about > > Vmotion as a ''killer technology'' when Xen is already doing it. > > If you read the interview there''s quite a bit of Xen-bashing. The guy > > rags on the requirement for modification of the host kernel. He is > > comparing the two products as if they took the same approach, failing to > > mention that Xen''s paravirtualisation architecture eliminates all of the > > costly performance overhead his company''s product is famous for... > > I still think you need to respect VMWare for breathing new life into > virtual machine research. And I still think Xen can be improved (as is > happening now) with regards to memory footprint etc. VMWare ESX is also > likely to have some performance benefits from having the drivers in the > kernel, even though that comes at the cost of them having to implement > the drivers themselves. And the fact that they can host Windows is a big > win with lots of customers. > > VMWare does some amount of paravirtualization, with all the VMWare tools > that you need to install. In fact, Xen seems to be going in VMWare''s > direction (shadow page tables, writable page tables, binary rewriting, > Vanderpool support) in some areas.Jacob, I am surprised here. Which code in Xen that does "binary rewriting"? Thank you, AQ ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
aq wrote:> On Wed, 16 Feb 2005 14:50:23 -0800, Jacob Gorm Hansen <jacobg@diku.dk> wrote: >>>VMWare does some amount of paravirtualization, with all the VMWare tools >>that you need to install. In fact, Xen seems to be going in VMWare''s >>direction (shadow page tables, writable page tables, binary rewriting, >>Vanderpool support) in some areas. > > > Jacob, I am surprised here. Which code in Xen that does "binary rewriting"?I am not sure if it is still there, but one of the approaches to fixing the /lib/tls issue was to use binary rewriting of code within the guest OS. Jacob ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
> Tom Hibbert wrote: > > Typical corporate talking head blah. Interesting that he talks about > > Vmotion as a ''killer technology'' when Xen is already doing it. > > If you read the interview there''s quite a bit of Xen-bashing. The guy > > rags on the requirement for modification of the host kernel. He is > > comparing the two products as if they took the same approach, failing to > > mention that Xen''s paravirtualisation architecture eliminates all of the > > costly performance overhead his company''s product is famous for... > > I still think you need to respect VMWare for breathing new life into > virtual machine research. And I still think Xen can be improved (as is > happening now) with regards to memory footprint etc. VMWare ESX is also > likely to have some performance benefits from having the drivers in the > kernel, even though that comes at the cost of them having to implement > the drivers themselves. And the fact that they can host Windows is a big > win with lots of customers.VMWare deserve respect for doing a /heroic/ engineering job; there are (as we all know) a bunch of really tricky hurdles to get over in order to do full (or almost full) virtualization on regular x86 hardware. I imagine there is some incredibly intricate and hairy code in there to deal with the binary scanning + rewriting, etc. That said, they may be solving the /wrong/ problem. As Xen (and other systems, e.g. exokernel) have demonstrated, most punters don''t give a damn if their OS is bit for bit identical or not providing all of their applications run correctly. Doing all the heavy lifting of full virtualization means that you have lots of complex (and fragile) code, and also pay a hefty performance cost. It only makes sense if you want to play the licensing game... which is kinda up in the air at the moment (e.g. if you experience difficulties w/ windows under vmware you need to reliably reproduce it under a vanilla install too or MS won''t support it).> VMWare does some amount of paravirtualization, with all the VMWare tools > that you need to install. In fact, Xen seems to be going in VMWare''s > direction (shadow page tables, writable page tables, binary rewriting, > Vanderpool support) in some areas.Hmm: - our shadow page tables are quite different to VMware''s (as far as we can tell - there''s no docs on their implementation details) - I don''t think that writable page tables are something VMWare do since it only makes sense for paravirtualized memory systems. - our binary rewriting is a tiny fraction of what they do and, in current default installs of xen 2.x, is not used at all. - we released VT support back in 2004; I don''t believe VMWare ship anything supporting VT at present. Anyway, the game may well change with the advent of VT and Pacifica; there are certainly both technical and legal/economic challenges to be overcome. cheers, S. ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
Steven Hand wrote:>>VMWare does some amount of paravirtualization, with all the VMWare tools >>that you need to install. In fact, Xen seems to be going in VMWare''s >>direction (shadow page tables, writable page tables, binary rewriting, >>Vanderpool support) in some areas. > > Hmm: > > - our shadow page tables are quite different to VMware''s (as far as > we can tell - there''s no docs on their implementation details) > > - I don''t think that writable page tables are something VMWare do > since it only makes sense for paravirtualized memory systems. > > - our binary rewriting is a tiny fraction of what they do and, in > current default installs of xen 2.x, is not used at all. > > - we released VT support back in 2004; I don''t believe VMWare > ship anything supporting VT at present.What I meant by that is that where Xen1 was purely in the paravirt camp, recent versions take more of a middle-of-the road stance, as Xen now sports functionality that does not strictly _have_ to be in the VMM, and does so in order to reduce the porting effort for new guest OSes. Jacob ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
On Thu, 17 Feb 2005, Steven Hand wrote:> That said, they may be solving the /wrong/ problem.I''m not so sure that is correct. I''ve talked to people in the commercial world and learned some interesting things. A big use of vmware and citrix is to run windows under windows. Why? Because nobody trusts windows or windows users. They run citrix (and I guess vmware in other places) 4 or 5 instances at a time under NT server and use KVMs. This one person I talked to ran thousands of desktops this way. I''m guessing based on some of my conversations that the big end use of vmware is windows under windows. But I could be totally wrong. ron ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
Actually, the biggest appeal of vmware is being able to run windows in a vm. Most organizations don''t really care what is underlying, but it''s the ability to snapshot and restore a virtual machine to a known working condition (particularly with windows) that appeals. The faster this restore happens, the better. They want the ability to immediately back out a hotfix or service pack (or any other software upgrade or config. change) that is causing issues and know that "ALL" traces of the offending change have been removed - immediately. No fussing around with regedit or dll version skew. This is especially true with terminal servers. If you have your corporate desktop sitting on a terminal server (say 250-500) users and someone infects the box with a virus or spyware, the faster you can get the box back to a pristine working condition, the more of a hero you look. It''s the same reason large corporations look to ghost for their desktop builds. On Thu, 2005-02-17 at 11:51, Ronald G. Minnich wrote:> On Thu, 17 Feb 2005, Steven Hand wrote: > > > That said, they may be solving the /wrong/ problem. > > I''m not so sure that is correct. I''ve talked to people in the commercial > world and learned some interesting things. A big use of vmware and citrix > is to run windows under windows. Why? Because nobody trusts windows or > windows users. They run citrix (and I guess vmware in other places) 4 or 5 > instances at a time under NT server and use KVMs. This one person I talked > to ran thousands of desktops this way. > > I''m guessing based on some of my conversations that the big end use of > vmware is windows under windows. But I could be totally wrong. > > ron > > > ------------------------------------------------------- > SF email is sponsored by - The IT Product Guide > Read honest & candid reviews on hundreds of IT Products from real users. > Discover which products truly live up to the hype. Start reading now. > http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/xen-devel >------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel