From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Wed, 07 Nov 2007 17:34:19 -0800 (PST)
Message-Id: <20071107.173419.22426986.davem@davemloft.net>
Subject: Re: [patch] radix-tree: avoid atomic allocations for preloaded
 insertions
From: David Miller <davem@davemloft.net>
In-Reply-To: <20071107170923.6cf3c389.akpm@linux-foundation.org>
References: <20071108004304.GD3227@wotan.suse.de>
	<20071107170923.6cf3c389.akpm@linux-foundation.org>
Mime-Version: 1.0
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Sender: owner-linux-mm@kvack.org
From: Andrew Morton <akpm@linux-foundation.org>
Date: Wed, 7 Nov 2007 17:09:23 -0800
Return-Path: <owner-linux-mm@kvack.org>
To: akpm@linux-foundation.org
Cc: npiggin@suse.de, linux-mm@kvack.org
List-ID: <linux-mm.kvack.org>

> Why not just stomp the warning with __GFP_NOWARN?
> 
> Did you consider turning off __GFP_HIGH?  (Dunno why)
> 
> This change will slow things down - has this been quantified?  Probably
> it's unmeasurable, but it's still there.
> 
> I'd have thought that a superior approach would be to just set
> __GFP_NOWARN?

I've rerun my test case which triggers this on Niagara 2
and I no longer get the messages.

For reference I first create N 16GB sparse files with
a script such as:

#!/bin/sh
#
# Usage: create_sparse NUM_FILES

for i in $(seq $1)
do
   dd if=/dev/zero of=sparse_file_$i bs=1MB count=1 seek=$((16 * 1024))
done

And then I fork off N threads, each running dd over one of
those sparse files with a script like:

#!/bin/sh
#
# Usage: thread_sparse NUM_THREADS

for i in $(seq $1)
do
    dd bs=1M if=sparse_file_$i of=/dev/null &
done

wait

On my Niagara 2 box I use '64' for 'N', so I go:

create_sparse 64
thread_sparse 64

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>