From: Nick Piggin <piggin@cyberone.com.au>
This patch removes ant_stats. Adds some comments where some
stats are incremented because they served as nice comments...
drivers/block/as-iosched.c | 102 ++++-----------------------------------------
1 files changed, 10 insertions(+), 92 deletions(-)
diff -puN drivers/block/as-iosched.c~as-remove-stats drivers/block/as-iosched.c
--- 25/drivers/block/as-iosched.c~as-remove-stats 2003-03-24 21:28:33.000000000 -0800
+++ 25-akpm/drivers/block/as-iosched.c 2003-03-24 21:34:05.000000000 -0800
@@ -22,35 +22,6 @@
#include <linux/rbtree.h>
#include <linux/interrupt.h>
-struct ant_stats {
- int reads; /* total read requests */
- int writes; /* total write requests */
- int anticipate_starts;
- int expired_read_batches;
- int expired_write_batches;
- int timeouts;
- int kblockd_calls;
- int anticipate_hits;
- int expired_fifo_reads;
- int expired_fifo_writes;
- int close_requests;
- int matching_ids;
- int broken_by_write;
- int exitted_tasks;
- int queued_request;
- int dispatched_request;
- int big_thinktime;
- int bad_ddir;
-
- int ant_delay_hist[100]; /* milliseconds */
-
- /*
- * This is a logarithmic (base 2) histogram
- */
- int lba_forward_offsets[BITS_PER_LONG];
- int lba_backward_offsets[BITS_PER_LONG];
-} ant_stats;
-
/*
* See Documentation/as-iosched.txt
*/
@@ -649,8 +620,6 @@ static void as_antic_waitreq(struct as_d
{
BUG_ON(ad->antic_status == ANTIC_FINISHED);
if (ad->antic_status == ANTIC_OFF) {
- ant_stats.anticipate_starts++;
-
if (!ad->as_io_context || ad->aic_finished)
as_antic_waitnext(ad);
else
@@ -684,7 +653,6 @@ static void as_antic_timeout(unsigned lo
struct as_data *ad = q->elevator.elevator_data;
int status = ad->antic_status;
- ant_stats.timeouts++;
if (status == ANTIC_WAIT_REQ || status == ANTIC_WAIT_NEXT) {
ad->antic_status = ANTIC_FINISHED;
kblockd_schedule_work(&ad->antic_work);
@@ -735,7 +703,7 @@ static int as_can_break_anticipation(str
struct as_io_context *aic;
if (rq_data_dir(arq->request) == READ && as_close_req(ad, arq)) {
- ant_stats.close_requests++;
+ /* close request */
return 1;
}
@@ -744,39 +712,36 @@ static int as_can_break_anticipation(str
* In this situation status should really be FINISHED,
* however the timer hasn't had the chance to run yet.
*/
- ant_stats.timeouts++;
return 1;
}
aic = ad->as_io_context;
if (aic == arq->as_io_context) {
- ant_stats.matching_ids++;
- if (rq_data_dir(arq->request) == WRITE)
- ant_stats.broken_by_write++;
+ /* request from same process */
return 1;
}
if (aic && !test_bit(AS_TASK_RUNNING, &aic->state)) {
- ant_stats.exitted_tasks++;
+ /* process anticipated on has exitted */
return 1;
}
if (aic && atomic_read(&aic->nr_queued) > 0) {
- ant_stats.queued_request++;
+ /* process has more requests queued */
return 1;
}
if (aic && atomic_read(&aic->nr_dispatched) > 0) {
- ant_stats.dispatched_request++;
+ /* process has more requests dispatched */
return 1;
}
if (aic && aic->ttime_mean > ad->antic_expire) {
- ant_stats.big_thinktime++;
+ /* the process thinks too much between requests */
return 1;
}
if (aic && aic->mean_dir_after_read != READ) {
- ant_stats.bad_ddir++;
+ /* next request from this process will probably be a write */
return 1;
}
@@ -876,11 +841,6 @@ static void as_update_arq(struct as_data
{
const int data_dir = rq_data_dir(arq->request);
- if (data_dir == READ)
- ant_stats.reads++;
- else
- ant_stats.writes++;
-
/* keep the next_arq cache up to date */
ad->next_arq[data_dir] = as_choose_req(ad, arq, ad->next_arq[data_dir]);
@@ -889,41 +849,10 @@ static void as_update_arq(struct as_data
* or does it come from the same process as the one we are anticipating
* for?
*/
- if (ad->batch_data_dir == READ && ad->antic_status != ANTIC_FINISHED
- && as_can_break_anticipation(ad, arq)) {
- sector_t last = ad->last_sector[data_dir];
- sector_t this = arq->request->sector;
- unsigned long delay;
- long lba_offset;
- int neg;
- int log2;
-
- if (ad->antic_status == ANTIC_WAIT_REQ)
- delay = 0;
- else
- delay = jiffies - ad->antic_start;
-
- if (data_dir == READ) {
- if (delay >= ARRAY_SIZE(ant_stats.ant_delay_hist))
- delay = ARRAY_SIZE(ant_stats.ant_delay_hist)-1;
- ant_stats.ant_delay_hist[delay]++;
- ant_stats.anticipate_hits++;
-
- lba_offset = this - last;
- neg = 0;
- if (lba_offset < 0) {
- lba_offset = -lba_offset;
- neg = 1;
- }
- log2 = ffs(lba_offset);
- if (neg)
- ant_stats.lba_backward_offsets[log2]++;
- else
- ant_stats.lba_forward_offsets[log2]++;
- }
-
+ if (ad->batch_data_dir == READ
+ && ad->antic_status != ANTIC_FINISHED
+ && as_can_break_anticipation(ad, arq))
as_antic_stop(ad);
- }
}
/*
@@ -1139,13 +1068,6 @@ static int as_dispatch_request(struct as
if (!(reads || writes))
return 0;
- if (as_batch_expired(ad)) {
- if (ad->batch_data_dir == READ)
- ant_stats.expired_read_batches++;
- else
- ant_stats.expired_write_batches++;
- }
-
if (!(reads && writes && as_batch_expired(ad)) ) {
/*
* batch is still running or no reads or no writes
@@ -1217,10 +1139,6 @@ dispatch_request:
if (as_fifo_expired(ad, ad->batch_data_dir)) {
fifo_expired:
- if (ad->batch_data_dir == WRITE)
- ant_stats.expired_fifo_writes++;
- else
- ant_stats.expired_fifo_reads++;
arq = list_entry_fifo(ad->fifo_list[ad->batch_data_dir].next);
BUG_ON(arq == NULL);
}
_