Messages in this thread | | | Date | Sun, 16 Aug 2009 11:08:49 -0600 | From | Robert Hancock <> | Subject | Re: Discard support (was Re: [PATCH] swap: send callback when swap slot is freed) |
| |
On 08/15/2009 11:39 AM, jim owens wrote: > ***begin rant*** > > I have not seen any analysis of the benefit and cost to the > end user of the TRIM or array UNMAP. We now see that TRIM > as implemented by some (all?) SSDs will come at high cost. > The cost is all born by the host. Do we get any benefit, or > is it all for the device vendor. And when we subtract the cost > from the benefit, does the user actually benefit and how? > > I'm tired of working around shit storage products and broken > device protocols from the "T" committees. I suggest we just > add a "white list" of devices that handle the discard fast > and without us needing NCQ queue drain. Then only send TRIM > to devices that are on the white list and throw the others > away in the block device layer.
They all will require NCQ queue drain. It's an inherent requirement of the protocol that you can't overlap NCQ and non-NCQ commands, and the trim command is not NCQ.
| |