From: Nick Piggin <piggin@cyberone.com.au>
Gets rid of the silly (and undocumented) trinary stateness of
ad->changed_batch.
Kernel style flags field could now save 20 bytes per asd (request queue) and
4 per arq. But I figure that change can wait until I do autotuning...
drivers/block/as-iosched.c | 35 +++++++++++++++++++++++------------
1 files changed, 23 insertions(+), 12 deletions(-)
diff -puN drivers/block/as-iosched.c~as-no-trinary-states drivers/block/as-iosched.c
--- 25/drivers/block/as-iosched.c~as-no-trinary-states 2003-08-05 21:47:52.000000000 -0700
+++ 25-akpm/drivers/block/as-iosched.c 2003-08-05 21:47:52.000000000 -0700
@@ -101,7 +101,8 @@ struct as_data {
struct list_head *hash; /* request hash */
unsigned long current_batch_expires;
unsigned long last_check_fifo[2];
- int changed_batch;
+ int changed_batch; /* 1: waiting for old batch to end */
+ int new_batch; /* 1: waiting on first read complete */
int batch_data_dir; /* current batch REQ_SYNC / REQ_ASYNC */
int write_batch_count; /* max # of reqs in a write batch */
int current_write_count; /* how many requests left this batch */
@@ -910,8 +911,13 @@ static void as_completed_request(request
return;
if (ad->changed_batch && ad->nr_dispatched == 1) {
+ WARN_ON(ad->batch_data_dir == arq->is_sync);
+
kblockd_schedule_work(&ad->antic_work);
- ad->changed_batch = 2;
+ ad->changed_batch = 0;
+
+ if (ad->batch_data_dir == REQ_SYNC)
+ ad->new_batch = 1;
}
ad->nr_dispatched--;
@@ -920,12 +926,12 @@ static void as_completed_request(request
* actually serviced. This should help devices with big TCQ windows
* and writeback caches
*/
- if (ad->batch_data_dir == REQ_SYNC && ad->changed_batch
- && ad->batch_data_dir == arq->is_sync) {
+ if (ad->new_batch && ad->batch_data_dir == arq->is_sync) {
+ WARN_ON(ad->batch_data_dir != REQ_SYNC);
update_write_batch(ad);
ad->current_batch_expires = jiffies +
ad->batch_expire[REQ_SYNC];
- ad->changed_batch = 0;
+ ad->new_batch = 0;
}
if (!arq->io_context)
@@ -1070,7 +1076,7 @@ static int as_fifo_expired(struct as_dat
*/
static inline int as_batch_expired(struct as_data *ad)
{
- if (ad->changed_batch)
+ if (ad->changed_batch || ad->new_batch)
return 0;
if (ad->batch_data_dir == REQ_SYNC)
@@ -1150,7 +1156,7 @@ static int as_dispatch_request(struct as
if (!(reads || writes)
|| ad->antic_status == ANTIC_WAIT_REQ
|| ad->antic_status == ANTIC_WAIT_NEXT
- || ad->changed_batch == 1)
+ || ad->changed_batch)
return 0;
if (!(reads && writes && as_batch_expired(ad)) ) {
@@ -1232,14 +1238,19 @@ fifo_expired:
}
if (ad->changed_batch) {
- if (ad->changed_batch == 1 && ad->nr_dispatched)
+ WARN_ON(ad->new_batch);
+
+ if (ad->nr_dispatched)
return 0;
- if (ad->batch_data_dir == REQ_ASYNC) {
+
+ if (ad->batch_data_dir == REQ_ASYNC)
ad->current_batch_expires = jiffies +
ad->batch_expire[REQ_ASYNC];
- ad->changed_batch = 0;
- } else
- ad->changed_batch = 2;
+ else
+ ad->new_batch = 1;
+
+ ad->changed_batch = 0;
+
arq->request->flags |= REQ_SOFTBARRIER;
}
_