Re: [PATCH v2 5/6] hisi_sas: add hisi_sas_slave_configure()

[Hannes Reinecke]

On 02/25/2016 05:42 PM, John Garry wrote:
> In high-datarate aging tests, it is found that the
> SCSI framework can periodically issue lu resets as
> some commands timeout.
> Response TASK SET FULL and SAS_QUEUE_FULL may be
> returned many times for the same command, causing the
> timeouts.
> The SAS_QUEUE_FULL errors come from
> TRANS_TX_CREDIT_TIMEOUT_ERR, TRANS_TX_CLOSE_NORMAL_ERR,
> and TRANS_TX_ERR_FRAME_TXED errors. They do not mean
> that the queue is full in the host, but rather it is
> equivalent to meaning the queue is full for the sdev.
> To overcome this, the queue depth for the sdev is
> reduced to 64 (from 256, set in sas_slave_configure()).
> Normally error code SAS_QUEUE_FULL will result in the
> sdev queue depth falling, but it falls too slowly during
> high-datarate tests and commands timeout before it
> has fallen to an adequete level from original value.
> 
> Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
> ---
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
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