Re: [PATCH v3 1/2] block: skip elevator data initialization for flush requests

(off-list ancestor, not in this archive)
[KNOWN BUGGY RFC PATCH 4/3] block: skip elevator initialization for flush requests · Mike Snitzer <hidden> · 2011-01-25
Re: [KNOWN BUGGY RFC PATCH 4/3] block: skip elevator initialization for flush requests · Mike Snitzer <hidden> · 2011-01-25
Re: [RFC PATCH 4/3] block: skip elevator initialization for flush requests -- was never BUGGY relative to upstream · Mike Snitzer <hidden> · 2011-01-26
Re: [KNOWN BUGGY RFC PATCH 4/3] block: skip elevator initialization for flush requests · Tejun Heo <tj@kernel.org> · 2011-01-26
Re: [KNOWN BUGGY RFC PATCH 4/3] block: skip elevator initialization for flush requests · Tejun Heo <tj@kernel.org> · 2011-01-26
Re: [RFC PATCH 4/3] block: skip elevator initialization for flush requests · Mike Snitzer <hidden> · 2011-02-01
Re: [RFC PATCH 4/3] block: skip elevator initialization for flush requests · Tejun Heo <tj@kernel.org> · 2011-02-01
[PATCH v2 2/2] block: share request flush fields with elevator_private · Mike Snitzer <hidden> · 2011-02-01
Re: [PATCH v2 2/2] block: share request flush fields with elevator_private · Vivek Goyal <vgoyal@redhat.com> · 2011-02-02
Re: [PATCH v2 2/2] block: share request flush fields with elevator_private · Tejun Heo <tj@kernel.org> · 2011-02-03
Re: [PATCH v2 2/2] block: share request flush fields with elevator_private · Jens Axboe <hidden> · 2011-02-11
[PATCH v2 1/2] block: skip elevator initialization for flush requests · Mike Snitzer <hidden> · 2011-02-01
Re: [PATCH v2 1/2] block: skip elevator initialization for flush requests · Vivek Goyal <vgoyal@redhat.com> · 2011-02-02
Re: [PATCH v2 1/2] block: skip elevator initialization for flush requests · Mike Snitzer <hidden> · 2011-02-02
[PATCH v3 1/2] block: skip elevator data initialization for flush requests · Mike Snitzer <hidden> · 2011-02-02
Re: [PATCH v3 1/2] block: skip elevator data initialization for flush requests · Tejun Heo <tj@kernel.org> · 2011-02-03
[PATCH v4 1/2] block: skip elevator data initialization for flush requests · Mike Snitzer <hidden> · 2011-02-03
Re: [PATCH v3 1/2] block: skip elevator data initialization for flush requests · Jens Axboe <hidden> · 2011-02-03
Re: [PATCH v3 1/2] block: skip elevator data initialization for flush requests · Tejun Heo <tj@kernel.org> · 2011-02-03
Re: [PATCH v3 1/2] block: skip elevator data initialization for flush requests · Vivek Goyal <vgoyal@redhat.com> · 2011-02-04
Re: [PATCH v3 1/2] block: skip elevator data initialization for flush requests · Tejun Heo <tj@kernel.org> · 2011-02-04
[PATCH v5 1/2] block: skip elevator data initialization for flush requests · Mike Snitzer <hidden> · 2011-02-04
Re: [PATCH v3 1/2] block: skip elevator data initialization for flush requests · Mike Snitzer <hidden> · 2011-02-03

From: Tejun Heo <tj@kernel.org>
Date: 2011-02-03 09:28:30
Also in: lkml

Hello,

On Wed, Feb 02, 2011 at 05:55:49PM -0500, Mike Snitzer wrote:

quoted hunk ↗ jump to hunk

@@ -808,9 +808,14 @@ static struct request *get_request(struc
 	rl->count[is_sync]++;
 	rl->starved[is_sync] = 0;
 
-	priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
-	if (priv)
-		rl->elvpriv++;
+	/*
+	 * Only initialize elevator data if REQ_SORTED is set.
+	 */
+	if (rw_flags & REQ_SORTED) {
+		priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
+		if (priv)
+			rl->elvpriv++;
+	}

This isn't enough.  Now the allocated requests would have REQ_SORTED
set before going into elevator.  You probably want to filter out
REQ_SORTED to elv_may_queue() too.

Also, it would be great if you update the comment on top of
get_request() to explain what @rw_flags does.

Thank you.

-- 
tejun

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