On Mon, Dec 11, 2006 at 08:52:22PM -0700, Matthew Wilcox wrote:
> On Tue, Dec 12, 2006 at 01:17:18AM -0200, Arnaldo Carvalho de Melo wrote:
> > }; /* size: 368, cachelines: 12 */
> > }; /* size: 364, cachelines: 12 */
>
> Saving space is always good ;-)
>
> > - unsigned int create:1; /* signal that it needs to be added */
> > + char scsi_level;
> > + unsigned char create:1; /* signal that it needs to be added */
> > unsigned int pdt_1f_for_no_lun; /* PDT = 0x1f */
> > /* means no lun present */
> >
> > - char scsi_level;
>
> However, pdt_1f_for_no_lun is really only one bit, saving another 4 bytes.
>
> > struct execute_work ew;
> > enum scsi_target_state state;
>
> enums are a bit of a pain. Even though scsi_target_state uses only two
> values, it's represented as an int. Unless you're on arm-eabi, when
> it'll use less. And even then, it won't use less than a byte, as it has
> to be addressable. I wonder if we can turn scsi_target_state into a
> bit. That'll save another 8 bytes total.
I guess we could use:
enum scsi_target_state state:1;
And make the enum entries start with 0 and not 1 as is today, no? With
that we get down to:
}; /* size: 356, cachelines: 12 */
/* last cacheline: 4 bytes */
Anything else to save these 4 bytes and get down to 11 cachelines per
scsi_target instance? Following patch is on top of the previous one.
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxx>
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index ab245fc..772f834 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -157,7 +157,7 @@ #define scmd_printk(prefix, scmd, fmt, a
dev_printk(prefix, &(scmd)->device->sdev_gendev, fmt, ##a)
enum scsi_target_state {
- STARGET_RUNNING = 1,
+ STARGET_RUNNING = 0,
STARGET_DEL,
};
@@ -176,12 +176,12 @@ struct scsi_target {
unsigned int id; /* target id ... replace
* scsi_device.id eventually */
char scsi_level;
+ enum scsi_target_state state:1;
unsigned char create:1; /* signal that it needs to be added */
- unsigned int pdt_1f_for_no_lun; /* PDT = 0x1f */
+ unsigned char pdt_1f_for_no_lun:1; /* PDT = 0x1f */
/* means no lun present */
struct execute_work ew;
- enum scsi_target_state state;
void *hostdata; /* available to low-level driver */
unsigned long starget_data[0]; /* for the transport */
/* starget_data must be the last element!!!! */
-
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