ZFS slow reads for unallocated blocks

[Chuck Burns]

On 4/11/2013 11:52 AM, Adam Nowacki wrote:
> This one is quite weird - reads from files that were created and resized
> with ftruncate (so no actual data on disk) are considerably slower and
> use more CPU time than files with data. If compression is enabled this
> will also affect files with long runs of zeroes as ZFS won't write any
> data to disk in this case. There is no I/O on the pool during the read
> tests - all fits into 10GB ARC.
>
> FreeBSD storage 9.1-RELEASE FreeBSD 9.1-RELEASE #0: Sat Feb 23 15:51:26
> UTC 2013     root at storage:/usr/obj/usr/src/sys/GENERIC  amd64
<snip>

Sounds like it could be a CPU bottleneck? How about some cpu info?


-- 
Chuck Burns <break19 at gmail.com>