On Tue, Jun 07 2005, Tony Battersby wrote: > > > My company (Cybernetics) sells several products that run embedded > Linux > > > which use the userspace scatter-gather capability of the SG driver. > > > They are still running the 2.4 kernel series, but we will probably > > > switch to 2.6 at some point. > > > > What do they actually use it for? As in why is the data scattered > even > > in the virtual address space? > > One of our products is a RAID-like controller for SCSI tape drives. > Parallel SCSI or iSCSI in via a target-mode SCSI driver and parallel > SCSI, iSCSI, or FC out via the SG driver, with various functions in > between for data buffering, emulation, striping, mirroring, etc. The > program that controls everything has a complex internal buffering scheme > that uses userspace scatter-gather for the main read/write I/O path to > the tape drives. That sounds like a valid use. Either way, I don't think we should remove such a feature. It's a sane feature, and people might be using it - there's no excuse for removing it. Should we kill readv next? :) -- Jens Axboe
