On 04/26/2010 10:42 AM, Martin K. Petersen wrote:
"Mark" == Mark Lord<kernel@xxxxxxxxxxxx> writes:
Mark> So.. again.. in an ideal kernel, I'd like to see use of larger
Mark> ranges (and _multiple_ ranges) per TRIM command. And options for
Mark> the kernel to do it automatically (-o discard), as well as an
Mark> ioctl() interface for userspace to "scrub" (or "wipe") all free
Mark> ranges in a gradual fashion.
Again: Discard splitting, merging, and coalescing is coming. I'm
working on it. It's not exactly trivial.
My objection was purely wrt. nuking realtime discard in favor of
scrubbing. We absolutely need both approaches.
But I'm not going to let crappy SSD firmware implementations set the
direction for what I'm working on. It is much more interesting to
ensure that we work well for the devices that'll be shipping 6-12 months
from now (at the time where this stuff will realistically end up in
distro kernels).
And one thing to keep in mind is that we are likely to need both run time
support for discard as well as occasional resync in bulk since the storage can
choose to ignore the command and still be in spec. Kind of like the unfortunate
"defrag" thing that windows people do,
ric
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