joel.bertr...@systella.fr (=?UTF-8?Q?BERTRAND_Jo=c3=abl?=) writes:
>186 MB/s for the first file. 18,7 MB/s for the second one and about 10
>MB/s fort the third one.
When dd gets slow, check with 'top' for what condition the processes
wait. Example for writing with 'dd' to a FFSv2 32kB blocks, 4k frags
backed by an iSCSI disk.
PID LID USERNAME PRI STATE TIME WCPU CPU NAME COMMAND
0 243 root 123 conn/2 0:05 5.96% 5.96% ConnSend [system]
3135 3135 mlelstv 85 pager_/0 0:02 3.28% 3.03% - dd
0 969 root 124 syncer/1 60:47 0.44% 0.44% ioflush [system]
0 9 root 125 vdrain/1 1:48 0.00% 0.00% vdrain [system]
0 17657 root 123 netio/1 0:01 0.00% 0.00% ConnRcv [system]
In this state I get about 680Mbit/s between a wm0 (client) and re0 (server).
The iSCSI server is istgt on an Intel Atom running NetBSD-9. The performance
is mostly limited by the server CPU.
ConnSend is waiting for something to do ("conn"), dd is waiting for I/O buffers
("pager_map"), ioflush waits for the syncer to flush the file cache ("syncer"),
vdrain is waiting for expunging vnodes when memory gets low ("vdrain") and
ConnRecv is waiting for a response from the iSCSI server.
--
--
Michael van Elst
Internet: mlel...@serpens.de
"A potential Snark may lurk in every tree."
