Tomorrow. Reviewing the qlogic net ones then have this on my todo.

On Aug 12, 2013, at 5:00 PM, Or Gerlitz <[email protected]> wrote:

> On Thu, Aug 8, 2013 at 4:25 PM, Or Gerlitz <[email protected]> wrote:
>> 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.
>> 
>> 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.
>> 
>> Using this patch in an accelerated version of the iser initiator we were
>> able to gain large improvements in IOPS rate in a situation where the burning
>> bottle-neck was the session lock.
> 
> Hi Mike and Co.
> 
> Any feedback on this patch?
> 
> Or.
> 
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