Messages in this thread | | | Date | Fri, 07 Dec 2012 23:24:34 +0100 | From | Paolo Bonzini <> | Subject | Re: [PATCH] scsi_ram: a RAM-based SCSI driver |
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Il 07/12/2012 12:20, Kirill A. Shutemov ha scritto: >> > Is this that much faster than scsi-debug? The discarding options surely >> > can be added there. > scsi_ram is about 9% faster (without fake_rw/throw_away_*) on my machine:
There are two main differences in the data path:
- scsi_debug uses locking. Shouldn't be the culprit because otherwise read and write would have different speed, but it's easy to add it to scsi_ram and check.
- scsi_debug uses scsi_sg_copy_to_buffer, i.e. sg_miter_start/next/stop in kernel/scatterlist.c. Again, it should be easy to port the scsi_ram code to scsi_debug or vice versa and verify if this is the culprit.
Having a completely different driver seems useless to me...
Paolo
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