[gpfsug-discuss] LROC nvme small IO size 4 k
Matt Weil
mweil at wustl.edu
Thu Jan 26 20:20:00 GMT 2017
I still see small 4k IO's going to the nvme device after changing the
max_sectors_kb. Writes did increase from 64 to 512. Is that a nvme
limitation.
> [root at ces1 system]# cat /sys/block/nvme0n1/queue/read_ahead_kb
> 8192
> [root at ces1 system]# cat /sys/block/nvme0n1/queue/nr_requests
> 512
> [root at ces1 system]# cat /sys/block/nvme0n1/queue/max_sectors_kb
> 8192
> [root at ces1 system]# collectl -sD --dskfilt=nvme0n1
> waiting for 1 second sample...
>
> # DISK STATISTICS (/sec)
> #
> <---------reads---------><---------writes---------><--------averages-------->
> Pct
> #Name KBytes Merged IOs Size KBytes Merged IOs Size RWSize
> QLen Wait SvcTim Util
> nvme0n1 47187 0 11K 4 30238 0 59 512
> 6 8 0 0 34
> nvme0n1 61730 0 15K 4 14321 0 28 512
> 4 9 0 0 45
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