On 04.09.2013 11:20, Johan Hendriks wrote:
Alexander Motin wrote:
I would like to invite more people to review and test my patches for
improving CAM and GEOM scalability, that for last six months you could
see developing in project/camlock SVN branch. Full diff of that branch
against present head (r255131) can be found here:
http://people.freebsd.org/~mav/camlock_patches/camlock_20130902.patch
Heavy CAM changes there were focused on reducing scope of SIM lock to
only protecting SIM internals, but not CAM core. That allows many
times reduce lock congestion, especially on heavily parallel request
submission with GEOM changes below. More detailed description of
changes you could see here earlier:
http://docs.freebsd.org/cgi/mid.cgi?520D4ADB.50209
GEOM changes were focused on avoiding switching to GEOM up/down
threads in relatively simple setups where respective classes don't
require it (and were explicitly marked so). That allows save on
context switches and on systems with several HBAs and disks talk to
them concurrently (that is where CAM locking changes are handy). Such
classes were modified to support it: DEV, DISK, LABEL, MULTIPATH, NOP,
PART, RAID (partially), STRIPE, ZERO, VFS, ZFS::VDEV, ZFS::ZVOL and
some others. Requests to/from other classes will be queued to GEOM
threads same as before.
Together that allows to double block subsystem performance on high (at
least 100-200K) IOPS benchmarks, allowing to reach up to a million
total IOPS, while keeping full compatibility with all major ABIs/KBIs.
Since we are already in 10.0 release process and changes are quite
big, my plan is to wait and commit them to head branch after the
freeze end, and then merge to stable/10. I hope the release process
will go on schedule to not delay this work for another six months.
This work is sponsored by iXsystems, Inc.
Hello i would like to test this patch set.
But how can i stress the machine, do you have a script or something i
can use to make the system do heavy I/O on the disks!
For testing IOPS over RAW disks or different GEOM providers (to exclude
FS influence) I am using such a trivial synthetic test:
#!/bin/sh
for disk in da0 da1 da2 da3 da4 da5 da6 da7 da8 da9 da10 da11 da12 da13
da14 da15
do
for i in `jot 16`
do
dd if=/dev/$disk of=/dev/null bs=512 &
done
done
iostat -zxw3 -c12 | grep total |tail -n 10 |cut -c 6-18
killall dd
For total IOPS measurement in above script I am using dirtily hacked
iostat tool that prints summary values in addition to per-disk ones:
http://people.freebsd.org/~mav/camlock_patches/iostat.patch
BTW I've uploaded new patch with some more minor CAM changes:
http://people.freebsd.org/~mav/camlock_patches/camlock_20130904.patch
--
Alexander Motin
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