2012-08-10 11:45:45

by majianpeng

Subject: [PATCH 2/3] block: Fix not tracing all device plug-operation.

If process handled two or more devices,there will not be trace some
devices plug-operation.

Signed-off-by: Jianpeng Ma <[email protected]>
---
block/blk-core.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 7a3abc6..034f186 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1521,11 +1521,25 @@ get_rq:
struct request *__rq;

__rq = list_entry_rq(plug->list.prev);
- if (__rq->q != q)
+ if (__rq->q != q) {
plug->should_sort = 1;
+ trace_block_plug(q);
+ }
+ } else {
+ struct request *__rq;
+ list_for_each_entry_reverse(__rq, &plug->list,
+ queuelist) {
+ if (__rq->q == q) {
+ list_add_tail(&req->queuelist,
+ &__rq->queuelist);
+ goto stat_acct;
+ }
+ }
+ trace_block_plug(q);
}
}
list_add_tail(&req->queuelist, &plug->list);
+stat_acct:
drive_stat_acct(req, 1);
} else {
spin_lock_irq(q->queue_lock);
--
1.7.9.5
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2012-08-10 13:09:58

by Jens Axboe

Subject: Re: [PATCH 2/3] block: Fix not tracing all device plug-operation.

On 08/10/2012 01:46 PM, Jianpeng Ma wrote:
> If process handled two or more devices,there will not be trace some
> devices plug-operation.
>
> Signed-off-by: Jianpeng Ma <[email protected]>
> ---
> block/blk-core.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 7a3abc6..034f186 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -1521,11 +1521,25 @@ get_rq:
> struct request *__rq;
>
> __rq = list_entry_rq(plug->list.prev);
> - if (__rq->q != q)
> + if (__rq->q != q) {
> plug->should_sort = 1;
> + trace_block_plug(q);
> + }
> + } else {
> + struct request *__rq;
> + list_for_each_entry_reverse(__rq, &plug->list,
> + queuelist) {
> + if (__rq->q == q) {
> + list_add_tail(&req->queuelist,
> + &__rq->queuelist);
> + goto stat_acct;

Did you verify this? It doesn't look right to me. You browse the list in
reverse, which means __rq is the first one that has a matching q. Then
you add the new req IN FRONT of that. You would want list_add() here
instead, adding it as the last member of that q string, not in the
middle.

--
Jens Axboe