Re: [Qemu-devel] disk cache question and drawback of cache

[Fam Zheng]

On Wed, 04/16 22:07, longguang.yue wrote:
> hi,all
> libvirt supply  "default", "none", "writethrough", "writeback", "directsync", 
> "unsafe" disk cache options
>  
>  
> 1.
> as for qemu,  how qemu uses those options? and  what are the differences?
> better  tell me where are the codes corresponding to those options?

Please see the explanations in qemu-doc:

http://wiki.qemu.org/download/qemu-doc.html

> 2.
> after a long time of running , it seems that vms will slow down?   do you 
> know why? 

Slow in doing what exactly? Disk? Network? CPU? Or memory access? Could you be
specific how you tested it? Could you show some data?

Thanks,
Fam