[PATCH] libata: reorder ata_queued_cmd to remove alignment paddingon 64 bit builds

From: Richard Kennedy
Date: Fri Sep 10 2010 - 07:20:25 EST


Reorder structure ata_queued_cmd to remove 8 bytes of alignment padding
on 64 bit builds & therefore reduce the size of structure ata_port by
256 bytes.

Overall this will have little impact, other than reducing the amount of
memory that is cleared when allocating ata_ports.

Signed-off-by: Richard Kennedy <richard@xxxxxxxxxxxxxxx>
----
patch against 2.6.36-rc3
compiled & tested on x86_64

I've been running this patch for a couple of weeks with no apparent
issues.

regards
Richard



diff --git a/include/linux/libata.h b/include/linux/libata.h
index f010f18..e115380 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -559,13 +559,13 @@ struct ata_queued_cmd {
unsigned int extrabytes;
unsigned int curbytes;

- struct scatterlist *cursg;
- unsigned int cursg_ofs;
-
struct scatterlist sgent;

struct scatterlist *sg;

+ struct scatterlist *cursg;
+ unsigned int cursg_ofs;
+
unsigned int err_mask;
struct ata_taskfile result_tf;
ata_qc_cb_t complete_fn;


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