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

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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@xxxxxxxxxxxxx>
Reviewed-by: Benjamin Block <bblock@xxxxxxxxxxxxx>
---
  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@xxxxxxxx>

Cheers,

Hannes
--
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@xxxxxxx			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)



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