ZFS and mem management

[George Kontostanos]

2012/2/15 Pavlo <devgs at ukr.net>:
>
>
>
>>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.
>
> Was going to try this... Thanks for reply.
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Why do you think that disabling prefetch is an overhead?


-- 
George Kontostanos
Aicom telecoms ltd
http://www.aisecure.net