linux-kernel - Re: [PATCH] block: trace all devices plug operation.

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Message-ID: <201309020954138877320@gmail.com>
Date:	Mon, 2 Sep 2013 09:54:16 +0800
From:	majianpeng <majianpeng@...il.com>
To:	axboe <axboe@...nel.dk>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] block: trace all devices plug operation.

Hi axboe:
	How about this patch?

Thanks!
Jianpeng Ma
>In func blk_queue_bio, if list of plug is empty,it will call
>blk_trace_plug.
>If process deal with a single device,it't ok.But if process deal with
>multi devices,it only trace the first device.
>Using request_count to judge, it can soleve this problem.
>
>In addition, i modify the comment.
>
>Signed-off-by: Jianpeng Ma <majianpeng@...il.com>
>---
> block/blk-core.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
>diff --git a/block/blk-core.c b/block/blk-core.c
>index 93a18d1..91037f7 100644
>--- a/block/blk-core.c
>+++ b/block/blk-core.c
>@@ -1549,11 +1549,9 @@ get_rq:
> 	if (plug) {
> 		/*
> 		 * If this is the first request added after a plug, fire
>-		 * of a plug trace. If others have been added before, check
>-		 * if we have multiple devices in this plug. If so, make a
>-		 * note to sort the list before dispatch.
>+		 * of a plug trace.
> 		 */
>-		if (list_empty(&plug->list))
>+		if (!request_count)
> 			trace_block_plug(q);
> 		else {
> 			if (request_count >= BLK_MAX_REQUEST_COUNT) {
>-- 
>1.8.3