Christoph Hellwig wrote:
On Sat, Nov 21, 2009 at 03:16:05PM -0500, Martin K. Petersen wrote:
I was trying to help Eric figure out why his drive pooped on big Trim
requests. For WRITE SAME the limit is inherent in the arguments,
whereas our SATL implementation is limited by the 512-byte WRITE SAME
payload. So I needed a way to convey this up the stack.
Since you already return a B0 VPD page I thought it would be a
convenient place to communicate the max without having to tweak the
queue limits directly from within libata.
You are right that I'm relying on fuzziness in SBC which requires both
the max LBA count and the descriptor count to be specified for UNMAP.
I think the better way is to make sure we can support any TRIM that
can be sent down. Given that TRIM is not NCQ-capable we can just
allocate one buffer for the TRIM ranges per TRIM capable device.
..
Good approach.
I suppose that buffer would be only 512 bytes long, per device?
That might be a bit restrictive, as TRIM can handle much larger
requests, and some drives (Indinlinx-based at least) prefer large
TRIM lists at present.
On the other hand, the Marvell chipsets cannot handle more than a
single sector of data without first fixing the driver to work around
chipset bugs. That's probably unique to sata_mv, though.
Cheers
Mark Lord
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