Date: Mon, 1 Mar 2004 14:31:39 -0800
From: Andrew Morton <akpm@osdl.org>
To: kenneth.w.chen@intel.com, linux-kernel@vger.kernel.org
Subject: Re: per-cpu blk_plug_list
Message-Id: <20040301143139.474fe56e.akpm@osdl.org>
In-Reply-To: <20040301141728.71e49546.akpm@osdl.org>
References: <B05667366EE6204181EABE9C1B1C0EB501F2AB4C@scsmsx401.sc.intel.com>
	<20040301141728.71e49546.akpm@osdl.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1002
Lines: 27

Andrew Morton <akpm@osdl.org> wrote:
>
> @@ -1251,6 +1251,9 @@ void blk_run_queues(void)
>  {
>  	LIST_HEAD(local_plug_list);
>  
> +	if (list_empty(&blk_plug_list))
> +		return;
> +

hmm, no, that won't help.  There will always be at least one plugged disk.

Perhaps what we need here is a per-task container of "queues which I have
plugged".  Or, more accurately, "queues which need to be unplugged so that
I can complete".  It'll get tricky because in some situations a task can
need unplugging of a queue which it did not plug, and even a queue to which
it did not submit any I/O.

You should try just nuking the whole plugging scheme, btw.  Stick a bunch
of `return' statements at the top of all the plugging functions.  I bet
that would run nicely...

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/