Alexander Motin wrote:
Hi.
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!
regards
Johan
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