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scsi: reduce CONFIG_SCSI_CONSTANTS=y impact by 8k

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On 64 bit, struct error_info has 6 bytes of padding, which amounts to
over 4k of wasted space in the additional[] array. We could easily get
rid of that by instead using separate arrays for the codes and the
pointers. However, we can do even better than that and save an
additional 6 bytes per entry: In the table, just store the sizeof()
the corresponding string literal. The cumulative sum of these is then
the appropriate offset into additional_text, which is built from the
concatenation (with '\0's inbetween) of the strings.

$ scripts/bloat-o-meter /tmp/vmlinux vmlinux
add/remove: 0/0 grow/shrink: 1/1 up/down: 24/-8488 (-8464)
function                                     old     new   delta
scsi_extd_sense_format                       136     160     +24
additional                                 11312    2824   -8488

The Kconfig help text used to say that CONFIG_SCSI_CONSTANTS=y costs
around 75 KB, but that was a little exaggerated. The actual number was
closer to 44K, and 36K with this patch.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Douglas Gilbert <dgilbert@interlog.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Rasmus Villemoes
2016-03-22 20:32:05 +01:00
committed by Martin K. Petersen
parent 9d99a2e33a
commit e1f0bce3a0
2 changed files with 23 additions and 7 deletions
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4
drivers/scsi/Kconfig
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@@ -202,12 +202,12 @@ config SCSI_ENCLOSURE
certain enclosure conditions to be reported and is not required.
config SCSI_CONSTANTS
bool "Verbose SCSI error reporting (kernel size +=75K)"
bool "Verbose SCSI error reporting (kernel size += 36K)"
depends on SCSI
help
The error messages regarding your SCSI hardware will be easier to
understand if you say Y here; it will enlarge your kernel by about
75 KB. If in doubt, say Y.
36 KB. If in doubt, say Y.
config SCSI_LOGGING
bool "SCSI logging facility"