Re: Badness in as_completed_request warning

Nick Piggin
2003-09-09T03:41:43Z

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Hi Dave,
Can you try 2.6.0-test5 with the following patch please. Thanks

Dave Olien wrote:

>I'm getting a "badness" warning from as_iosched.c, line 917.
>This is on 2.6.0-test4-mm6, running on a 2 cpu x86.
>
>The warning occurs when I run three or more instances of mkfs.ext2, where
>each mkfs is running on its own disk. If I run four or more mkfs's
>on paritions all on the same disk I don't get this warning.
>The more instances of mkfs I run (each on separate disks), the
>more instances of this warning I receive.
>
>The mkfs's all progress at the same rate. The warnings
>occur as all mkfs's are "writing superblocks and filesystem
>accounting information", near the end of the mkfs.
>
># Badness in as_completed_request at drivers/block/as-iosched.c:917
>
>Call Trace:
> [<c0220d0d>] as_completed_request+0x1ad/0x1b0
> [<c021946f>] elv_completed_request+0x1f/0x30
> [<c021b87c>] __blk_put_request+0x3c/0xc0
> [<c021c83f>] end_that_request_last+0x5f/0xf0
> [<c0234d02>] DAC960_V2_ProcessCompletedCommand+0x172/0xf50
> [<c029712a>] ip_rcv+0x39a/0x520
> [<c011ebf4>] recalc_task_prio+0xb4/0x1f0
> [<c011f64b>] load_balance+0x1bb/0x430
> [<c0235bfd>] DAC960_LP_InterruptHandler+0x6d/0xb0
> [<c010e789>] handle_IRQ_event+0x49/0x80
> [<c010eb00>] do_IRQ+0xa0/0x150
> [<c010abd0>] default_idle+0x0/0x40
> [<c02f2f8c>] common_interrupt+0x18/0x20
> [<c010abd0>] default_idle+0x0/0x40
> [<c010abfd>] default_idle+0x2d/0x40
> [<c010ac96>] cpu_idle+0x46/0x50
> [<c0107000>] rest_init+0x0/0x60
> [<c039092d>] start_kernel+0x18d/0x1c0
> [<c03904a0>] unknown_bootoption+0x0/0x120
>
>
>
>
>

[-- Attachment #2: as-warn-fix.patch --]
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linux-2.6-npiggin/drivers/block/as-iosched.c | 23 +++++++++++++++++++++++
1 files changed, 23 insertions(+)

diff -puN drivers/block/as-iosched.c~as-warn-fix drivers/block/as-iosched.c
--- linux-2.6/drivers/block/as-iosched.c~as-warn-fix 2003-09-09 13:01:04.000000000 +1000
+++ linux-2.6-npiggin/drivers/block/as-iosched.c 2003-09-09 13:21:12.000000000 +1000
@@ -381,8 +381,14 @@ static void as_add_arq_rb(struct as_data
arq->rb_key = rq_rb_key(rq);

/* This can be caused by direct IO */
+#if 0
while ((alias = __as_add_arq_rb(ad, arq)))
as_move_to_dispatch(ad, alias);
+#endif
+ if ((alias = __as_add_arq_rb(ad, arq))) {
+ list_add_tail(&arq->request->queuelist,
+ &alias->request->queuelist);
+ }

rb_insert_color(&arq->rb_node, ARQ_RB_ROOT(ad, arq));
}
@@ -1131,7 +1137,24 @@ static void as_move_to_dispatch(struct a
* take it off the sort and fifo list, add to dispatch queue
*/
as_remove_queued_request(ad->q, arq->request);
+
+ for (;;) {
+ struct list_head *alias = &arq->request->queuelist;
+
+ if (!list_empty(alias)) {
+ struct request *rq;
+ rq = list_entry_rq(alias->next);
+ list_del(&rq->queuelist);
+ list_add_tail(&rq->queuelist, ad->dispatch);
+
+ if (arq->io_context && arq->io_context->aic)
+ atomic_inc(&arq->io_context->aic->nr_dispatched);
+ } else
+ break;
+ }
+
list_add_tail(&arq->request->queuelist, ad->dispatch);
+
if (arq->io_context && arq->io_context->aic)
atomic_inc(&arq->io_context->aic->nr_dispatched);

_