Broken autoconf mmap test

Eric Blake eblake@redhat.com
Thu Mar 24 16:24:00 GMT 2011


On 03/24/2011 10:21 AM, Christopher Faylor wrote:
>> - In all three possible solutions above: What if the original file
>>  handle used in the mmap call has been closed and the file permissions
>>  have been changed in the meantime so that the process does not have
>>  write permissions anymore?
> 
> - Isn't it going to be really slow?  I guess if it only happens once
> per page it won't be that bad but still: ouch.

And if I'm understanding correctly, it only needs to happen for the one
page at the end of the file; all earlier 64k chunks of the file can be
mapped normally, if you can guarantee that the normal mappings are
adjacent with the one special mapping.

-- 
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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