[BLOCK] mark some block/ variables cons

the patch below marks various read-only variables in block/* as const,
so that gcc can optimize the use of them; eg gcc will replace the use by
the value directly now and will even remove the memory usage of these.

Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Jens Axboe <axboe@suse.de>

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index ee0bb41..74fae2d 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -25,15 +25,15 @@
 /*
  * tunables
  */
-static int cfq_quantum = 4;            /* max queue in one round of service */
-static int cfq_queued = 8;             /* minimum rq allocate limit per-queue*/
-static int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
-static int cfq_back_max = 16 * 1024;   /* maximum backwards seek, in KiB */
-static int cfq_back_penalty = 2;       /* penalty of a backwards seek */
+static const int cfq_quantum = 4;              /* max queue in one round of service */
+static const int cfq_queued = 8;               /* minimum rq allocate limit per-queue*/
+static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
+static const int cfq_back_max = 16 * 1024;     /* maximum backwards seek, in KiB */
+static const int cfq_back_penalty = 2;         /* penalty of a backwards seek */
 
-static int cfq_slice_sync = HZ / 10;
+static const int cfq_slice_sync = HZ / 10;
 static int cfq_slice_async = HZ / 25;
-static int cfq_slice_async_rq = 2;
+static const int cfq_slice_async_rq = 2;
 static int cfq_slice_idle = HZ / 100;
 
 #define CFQ_IDLE_GRACE         (HZ / 10)
@@ -45,7 +45,7 @@ static int cfq_slice_idle = HZ / 100;
 /*
  * disable queueing at the driver/hardware level
  */
-static int cfq_max_depth = 2;
+static const int cfq_max_depth = 2;
 
 /*
  * for the hash of cfqq inside the cfqd

diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index 9cbec09..27e494b 100644 (file)
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -19,10 +19,10 @@
 /*
  * See Documentation/block/deadline-iosched.txt
  */
-static int read_expire = HZ / 2;  /* max time before a read is submitted. */
-static int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
-static int writes_starved = 2;    /* max times reads can starve a write */
-static int fifo_batch = 16;       /* # of sequential requests treated as one
+static const int read_expire = HZ / 2;  /* max time before a read is submitted. */
+static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
+static const int writes_starved = 2;    /* max times reads can starve a write */
+static const int fifo_batch = 16;       /* # of sequential requests treated as one
                                     by the above parameters. For throughput. */
 
 static const int deadline_hash_shift = 5;

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 97f4e7e..e02c88c 100644 (file)
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -1039,7 +1039,7 @@ void blk_queue_invalidate_tags(request_queue_t *q)
 
 EXPORT_SYMBOL(blk_queue_invalidate_tags);
 
-static char *rq_flags[] = {
+static const char * const rq_flags[] = {
        "REQ_RW",
        "REQ_FAILFAST",
        "REQ_SORTED",

diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index 1d8852f..c2ac36d 100644 (file)
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -46,7 +46,7 @@ EXPORT_SYMBOL(scsi_command_size);
 
 static int sg_get_version(int __user *p)
 {
-       static int sg_version_num = 30527;
+       static const int sg_version_num = 30527;
        return put_user(sg_version_num, p);
 }