Re: [BENCHMARK] I/O regression after 2.6.0-test5

[Nick Piggin <piggin@cyberone.com.au>]

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rwhron@earthlink.net wrote:

>>If you have time, would you please try testing as-iosched.c from
>>test5 in a later kernel (it won't go into test8-mm1 though).
>>
>
>copying drivers/block/as-iosched.c from 2.6.0-test5 to test8
>looks like it fixes the regression.  Here are the results so far.
>

Could you please try the following patch against 2.6.0-test8.
Thanks. I'll have to come up with something more comprehensive
because this destroys find | xargs grep during other IO. It
looks like this might be the cause of a lot of AS's database
problems though.

I'm working on something...


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 linux-2.6-npiggin/drivers/block/as-iosched.c |   23 +++--------------------
 1 files changed, 3 insertions(+), 20 deletions(-)

diff -puN drivers/block/as-iosched.c~as-fix drivers/block/as-iosched.c
--- linux-2.6/drivers/block/as-iosched.c~as-fix	2003-10-22 19:47:48.000000000 +1000
+++ linux-2.6-npiggin/drivers/block/as-iosched.c	2003-10-22 19:49:41.000000000 +1000
@@ -99,7 +99,6 @@ struct as_data {
 	sector_t last_sector[2];	/* last REQ_SYNC & REQ_ASYNC sectors */
 	struct list_head *dispatch;	/* driver dispatch queue */
 	struct list_head *hash;		/* request hash */
-	unsigned long new_success; /* anticipation success on new proc */
 	unsigned long current_batch_expires;
 	unsigned long last_check_fifo[2];
 	int changed_batch;		/* 1: waiting for old batch to end */
@@ -585,18 +584,11 @@ static void as_antic_stop(struct as_data
 	int status = ad->antic_status;
 
 	if (status == ANTIC_WAIT_REQ || status == ANTIC_WAIT_NEXT) {
-		struct as_io_context *aic;
-
 		if (status == ANTIC_WAIT_NEXT)
 			del_timer(&ad->antic_timer);
 		ad->antic_status = ANTIC_FINISHED;
 		/* see as_work_handler */
 		kblockd_schedule_work(&ad->antic_work);
-
-		aic = ad->io_context->aic;
-		if (aic->seek_samples == 0)
-			/* new process */
-			ad->new_success = (ad->new_success * 3) / 4 + 256;
 	}
 }
 
@@ -612,14 +604,8 @@ static void as_antic_timeout(unsigned lo
 	spin_lock_irqsave(q->queue_lock, flags);
 	if (ad->antic_status == ANTIC_WAIT_REQ
 			|| ad->antic_status == ANTIC_WAIT_NEXT) {
-		struct as_io_context *aic;
 		ad->antic_status = ANTIC_FINISHED;
 		kblockd_schedule_work(&ad->antic_work);
-
-		aic = ad->io_context->aic;
-		if (aic->seek_samples == 0)
-			/* new process */
-			ad->new_success = (ad->new_success * 3) / 4;
 	}
 	spin_unlock_irqrestore(q->queue_lock, flags);
 }
@@ -708,11 +694,10 @@ static int as_can_break_anticipation(str
 		return 1;
 	}
 
-	if (ad->new_success < 256 &&
-			(aic->seek_samples == 0 || aic->ttime_samples == 0)) {
+	if (aic->seek_samples == 0 && aic->ttime_samples == 0) {
 		/*
-		 * Process has just started IO and we have a bad history of
-		 * success anticipating on new processes!
+		 * Process has just started IO. Don't anticipate.
+		 * TODO! Must fix this up.
 		 */
 		return 1;
 	}
@@ -1822,8 +1807,6 @@ static int as_init(request_queue_t *q, e
 	if (ad->write_batch_count < 2)
 		ad->write_batch_count = 2;
 
-	ad->new_success = 512;
-
 	return 0;
 }
 

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