Messages in this thread | | | Subject | Re: [PATCH 0/2] scsi: add support for request batching | From | Douglas Gilbert <> | Date | Wed, 26 Jun 2019 10:14:23 -0400 |
| |
On 2019-06-26 9:51 a.m., Paolo Bonzini wrote: > On 30/05/19 13:28, Paolo Bonzini wrote: >> This allows a list of requests to be issued, with the LLD only writing >> the hardware doorbell when necessary, after the last request was prepared. >> This is more efficient if we have lists of requests to issue, particularly >> on virtualized hardware, where writing the doorbell is more expensive than >> on real hardware. >> >> This applies to any HBA, either singlequeue or multiqueue; the second >> patch implements it for virtio-scsi. >> >> Paolo >> >> Paolo Bonzini (2): >> scsi_host: add support for request batching >> virtio_scsi: implement request batching >> >> drivers/scsi/scsi_lib.c | 37 ++++++++++++++++++++++--- >> drivers/scsi/virtio_scsi.c | 55 +++++++++++++++++++++++++++----------- >> include/scsi/scsi_cmnd.h | 1 + >> include/scsi/scsi_host.h | 16 +++++++++-- >> 4 files changed, 89 insertions(+), 20 deletions(-) >> > > > Ping? Are there any more objections?
I have no objections, just a few questions.
To implement this is the scsi_debug driver, a per device queue would need to be added, correct? Then a 'commit_rqs' call would be expected at some later point and it would drain that queue and submit each command. Or is the queue draining ongoing in the LLD and 'commit_rqs' means: don't return until that queue is empty?
So does that mean in the normal (i.e. non request batching) case there are two calls to the LLD for each submitted command? Or is 'commit_rqs' optional, a sync-ing type command?
Doug Gilbert
| |