On 10/27/13 8:23 AM, Or Gerlitz wrote:
Hi James,
This series is about reducing locking contention in the IO submission/response processing
fast path of libiscsi and the various iscsi transports usage of libiscsi code.
We replace the session lock with two locks, a forward lock and a backwards lock
named frwd_lock and back_lock respectively.
The forward lock protects resources that change while sending a request to the
target, such as cmdsn, queued_cmdsn, and allocating task from the commands'
pool with kfifo_out.
The backward lock protects resources that change while processing a response or
in error path, such as cmdsn_exp, cmdsn_max, and returning tasks to the commands'
pool with kfifo_in.
The 1st patch in the series is a restructuring patch for iscsi_tcp r2t response
logic, the 2nd is the main patch and the 3rd is cleanup asked by Mike who reviewed
the whole series when we posted in over the open-iscsi mailing list.
Under a "steady state" fast-path situation, that is when one or more processes/threads
submit IO to an iscsi device and a single kernel upcall (e.g softirq) is dealing
with processing of responses without errors, this patch eliminates the contention
between the queuecommand()/request response/scsi_done() associated with iscsi sessions.
Or and Shlomo.
Shlomo Pongratz (3):
SCSI/libiscsi: Restructure iscsi_tcp r2t response logic
SCSI/libiscsi: Reduce locking contention in fast path
SCSI/libiscsi: Remove unneeded code
Hi James,
I saw your git pull mail said it was the first round of patches. If you
are going to do a second round could you take the patches in this thread?
I had replied to the first mail in the thread with a signed-off line:
http://marc.info/?l=linux-scsi&m=138309757219394&w=2
It should have been a reviewed-by, so here is the proper tag.
Reviewed-by: Mike Christie <michaelc@xxxxxxxxxxx>
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