Re: [PATCH 11/23] zfcp: drop duplicate seq_no from zfcp_fsf_req which is also in QTCB header

Re: [PATCH 11/23] zfcp: drop duplicate seq_no from zfcp_fsf_req which is also in QTCB header

[Hannes Reinecke]

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On 11/8/18 3:44 PM, Steffen Maier wrote:
> There is no point for double bookkeeping especially just for tracing.
> The trace can take it from the QTCB which always exists for non-SRB
> responses traced with zfcp_dbf_hba_fsf_res().
> 
> As a side effect, this removes an alignment hole and reduces the
> size of struct zfcp_fsf_req, and thus of each pending request, by
> 8 bytes.
> Before:
> $ pahole -C zfcp_fsf_req drivers/s390/scsi/zfcp.ko
> ...
> 	struct fsf_qtcb *          qtcb;                 /*   144     8 */
> 	u32                        seq_no;               /*   152     4 */
> 	/* XXX 4 bytes hole, try to pack */
> 	void *                     data;                 /*   160     8 */
> ...
> 	/* size: 296, cachelines: 2, members: 14 */
> 	/* sum members: 288, holes: 2, sum holes: 8 */
> 	/* last cacheline: 40 bytes */
> After:
> $ pahole -C zfcp_fsf_req drivers/s390/scsi/zfcp.ko
> ...
> 	struct fsf_qtcb *          qtcb;                 /*   144     8 */
> 	void *                     data;                 /*   152     8 */
> ...
> 	/* size: 288, cachelines: 2, members: 13 */
>          /* sum members: 284, holes: 1, sum holes: 4 */
> 
> Signed-off-by: Steffen Maier <maier@linux.ibm.com>
> Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
> ---
>   drivers/s390/scsi/zfcp_dbf.c | 2 +-
>   drivers/s390/scsi/zfcp_def.h | 2 --
>   drivers/s390/scsi/zfcp_fsf.c | 1 -
>   3 files changed, 1 insertion(+), 4 deletions(-)
> 
Makes one wonder what we need the sequence number for ...

Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
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