Re: [Xen-users] xl save and compression

[Cyan <yann.collet.73@xxxxxxxxx>]

Sven KÃhler <sven.koehler <at> gmail.com> writes:

> 
> Hi,
> 
> So what I ended up doing is the following to save the state in 13
> instead of 90 seconds:
> 
> xl save myDomU /dev/stdout \
>       |  buffer -b 64 \
>       | lz4c -1 -f - myDomU.state.lz4
> 
> Then, why do I to need to use the buffer tool? Well, because it's faster
> that way. The problem is that fifos and pipes seem to have a buffer of
> only 64KB. And such a small buffer kills performance, especially if
> either xl save is writing in large chunks or lz4c is reading in large
> chunks. I think lz4c is to blame here, but I'm not quite sure.
> 
> 
> Regards,
>   Sven
> 


Could you try :

xl save myDomU /dev/stdout \
| lz4 -B4 -1 -f - myDomU.state.lz4


It should reduce the internal buffer size of lz4 to 64KB.


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