ZFS and mem management

[Ivan Voras]

On 15/02/2012 13:39, Pavlo wrote:
> 
> 
> 
> Unfortunately we can't afford disabling prefetch. It is too much of an
> overhead.
> 
> Also I made some tests. I have process that maps file using mmap() and
> writes or reads first byte of each page of mapped file with some data.

Note that ZFS is designed so that it interacts somewhat badly with
mmap() and other kernel services which rely on coherency between VM and
IO such as sendfile(). At the very best, you will have two in-kernel
copies of all data buffers used with such interfaces, but there have
been sporadic reports that there are other bugs with it.

If you have a test server, I'd recommend you do the same test on UFS for
comparison.

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