On Wed, 2014-03-12 at 21:47 -0400, Martin K. Petersen wrote: > I'm no big fan of dropping information. > > My original intent with the discard granularity and alignment was to > allow filesystems to use them to influence block allocation and layout. > Not to affect how we issue commands at runtime. > > Since a storage device is free to ignore all or parts of any discard > request I'd consider it somewhat broken if it actually complained. > Especially so since the relevant knobs in the standard that we key off > of are performance recommendations and not requirements that commands > must adhere to.
Well, in this particular case the driver is filling in the relevant information (alignment and granularity) and then complaining later that that information has been ignored. As I intimated earlier, it seems a little odd to allow the driver to specify the information, only to ignore it completely when it's time to actually use it. Further, in my opinion this is less "dropping information" than it is keeping information that would be dropped by the driver itself; were it not for this adjustment, the driver would get the request, complain, and drop it completely. This way, as much of the request as possible is preserved while still honoring the constraints given by the driver. -- Frank Mayhar 310-460-4042 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
