Hello,
On Fri, 16 Mar 2012, Shaohua Li wrote:
The patches add TRIM support for raid linear/0/1/10. I'll add TRIM support for
raid 4/5/6 later. The implementation is pretty straightforward and
self-explained.
v1->v2:
1. fixed a checking issue
2. dropped discard request plug and replace it with no discard merege, because
current SCSI layer can't handle discard request merge.
Have tested TRIM patches on three different systems with the following
hardware/ setup:
1) root mounted on a raid1 over two SAS SSD's (200GB) and /home partition
on a raid0 over a fusionio ioDrive Duo. Is very new and seen very
little usage.
2) root and /home mounted on a raid0 over two Intel X25 Postville
(160GB) connected to a Intel P55 Express chipset. Has seen very
heavy usage for approx. 2 years.
3) root and /home mounted on a raid0 over three OCZ-VERTEX2 (120GB)
connected via ICH7 south bridge. Has seen mild usage for approx.
1.5 years.
Made the following observations when running my own benchmark which
copies around a lot of small files and deletes them. The benchmark on
all systems was always run only on the /home partition ie. on a raid0.
For system 1) there is hardly any measurable differnce whether discard
is enabled or not (~29000 files per second).
On system 2) the performance drops from 6500->3700 files per second,
but under normal usage one does not notice any difference.
System 3) has problems during boot, it is so slow that some operations
receive a timeout during boot:
udevd[474]: timeout '/sbin/blkid -o udev -p /dev/md0'
udevd[474]: timeout: killing '/sbin/blkid -o udev -p /dev/md0' [866]
systemd[1]: dev-md3.swap activation timed out. Stopping.
Even removing discard does not help and the above errors happen during
boot and booting takes a long time.
The performance in the benchmark drops from 4000->600 files per second.
Regards,
Holger
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