ZFS and mem management

[Ivan Voras]

On 15/02/2012 17:07, Kai Gallasch wrote:
> 
> Am 15.02.2012 um 15:02 schrieb 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.
> 
> So best practice for running apache2 on FreeBSD ZFS is making sure EnableMMAP and EnableSendfile are disabled in httpd.conf, right?

Yes.

> (both are turned off by default)

No, they are enabled by default:

http://httpd.apache.org/docs/2.2/mod/core.html#enablemmap


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