Hi, 2016-01-30 0:05 GMT+08:00 Joe Thornber <[email protected]>:
> On Fri, Jan 29, 2016 at 07:01:44PM +0800, Dennis Yang wrote: > > I had tried to define MAX_DECS as 1, 16, and 8192, and here is the > > throughput I got. > > When #define MAX_DECS 1, throughput drops from 3.2GB/s to around 800 ~ > 950 > > MB/s. > > When #define MAX_DECS 16, throughput drops from 3.2GB/s to around 150 ~ > 400 > > MB/s > > When #define MAX_DECS 8192, the I/O blocks until deletion is done. > > > > These throughput is gathered by writing to a newly created thin device > > which means lots of provisioning take place. So it seems that the more > fine > > grained lock we use here results in the higher throughput. Is there any > > concern if I set MAX_DECS to 1 for production? > > Does the time taken to remove the thin device change as you drop it to one? > > - Joe > Not that I am aware of, but I redo the experiment and the results are listed below. #define MAX_DECS 1 Delete a fully-mapped 10TB device without concurrent I/O takes 49 secs. Delete a fully-mapped 10TB device with concurrent I/O to pool takes 44 secs. #define MAX_DECS 16 Delete a fully-mapped 10TB device without concurrent I/O takes 47 secs. Delete a fully-mapped 10TB device with concurrent I/O to pool takes 46 secs. #define MAX_DECS 8192 Delete a fully-mapped 10TB device without concurrent I/O takes 47 secs. Delete a fully-mapped 10TB device with concurrent I/O to pool takes 50 secs. Thanks, Dennis -- Dennis Yang QNAP Systems, Inc. Skype: qnap.dennis.yang Email: [email protected] Tel: (+886)-2-2393-5152 ext. 15018 Address: 13F., No.56, Sec. 1, Xinsheng S. Rd., Zhongzheng Dist., Taipei City, Taiwan
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