On 1/19/06, Juergen Pfennig <[EMAIL PROTECTED]> wrote: > What I found is that qcow has poor performance. I wrote my own driver > (which is intended only for -snapshot) and see signifcant improvements. > A 300 MByte file copy (win2003 xcopy /e between two real drives) takes > 90 instead of 135 seconds. I will send the patch to the list after it > has matured for a while. The thing is linux only for mmap() is used.
Hi, While you are at it, have you considered using the LZO libraries instead of zlib for compression/decompression speed? Sure, it won't compress as much as zlib, but speed improvements should be noticeable. I was thinking about doing this myself, but no doubt you now understand the relevant source code on a level I'll still take a few weeks to. The source code for LZO is GPL'd, though. If I understand it correctly, Mr. Oberhumer wouldn't mind doing an exception for QEMU and licensing it as LGPL in this particular case; anyway, he must be contacted to clarify this issue. Link: http://www.oberhumer.com/opensource/lzo/ > The thing is linux only for mmap() is used. On the link below you'll find some practical source code showing the differences between **nix mmap() and Windows' equivalents: http://www-128.ibm.com/developerworks/eserver/library/es-MigratingWin32toLinux.html Please consider using those so everyone can benefit ;) Thank you! -- "I decry the current tendency to seek patents on algorithms. There are better ways to earn a living than to prevent other people from making use of one's contributions to computer science." Donald Knuth _______________________________________________ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
