Date: Thu, 11 Apr 2013 12:02:50 -0500 From: Chuck Burns <break19@gmail.com> To: freebsd-fs@freebsd.org Subject: Re: ZFS slow reads for unallocated blocks Message-ID: <5166ECBA.1090005@gmail.com> In-Reply-To: <5166EA43.7050700@platinum.linux.pl> References: <5166EA43.7050700@platinum.linux.pl>
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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@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@gmail.com>
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