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Date: Fri, 21 Dec 2001 23:19:51 +0100
From: Jens Axboe <axboe@kernel.org>
To: rwhron@earthlink.net
Cc: linux-kernel@vger.kernel.org
Subject: Re: 2.5.2-pre1 dbench 32 hangs in vmstat "b" state
Message-ID: <20011221231951.F2929@suse.de>
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On Fri, Dec 21 2001, rwhron@earthlink.net wrote:
> On Fri, Dec 21, 2001 at 06:01:56PM +0100, Jens Axboe wrote:
> > Thanks -- could you also try and do sysrq-t back traces when it seems
> > stuck?
> > 
> > Does a non-highmem kernel run ok?
> > 
> > -- 
> > Jens Axboe
> 
> I recompiled with highmem turned off.  
> # CONFIG_HIGHMEM4G is not set
> # CONFIG_HIGHMEM64G is not set
> 
> I run a scripty that executes dbench 32, then dbench 128.

Ok, please try something for me. In drivers/block/elevator.c, comment
out this block:

	if (q->last_merge) {
		__rq = list_entry_rq(q->last_merge);
		BUG_ON(__rq->flags & REQ_STARTED);

		if ((ret = elv_try_merge(__rq, bio))) {
			*req = __rq;
			return ret;
		}
	}

(just #if 0 the entire thing) -- the one inside elevator_linus_merge()

Loop back highmem issue is different, I'll take a look at that later.
I'll be pretty unresponsive over christmas, though.

-- 
Jens Axboe

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