From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tao Ma <tm@tao.ma>
Date: Wed, 25 May 2011 06:19:12 +0000
Subject: Re: Seg fault in blkparse.
Message-Id: <4DDC9F60.9000507@tao.ma>
List-Id: <linux-btrace.vger.kernel.org>
References: <4DDC418E.4080407@broadley.org>
In-Reply-To: <4DDC418E.4080407@broadley.org>
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To: linux-btrace@vger.kernel.org

On 05/25/2011 07:38 AM, Bill Broadley wrote:
> 
> I recorded a 3 minutes of heavy IO (generated with fio) with:
> blktrace -w 240 -a read -a write -a fs -I devs -o btrfs-12-blk.log
> 
> (I used 240 seconds to make sure I didn't miss any of the 180 seconds of
> I/O).
> 
> As a small aside I wasn't sure what the default filter mask was, it
> seems more correct to use:
> blktrace -w 240 -A read -a write -a fs -I devs -o btrfs-12-blk.log
> 
> So set the mask to exactly (and only) read, then add write, and fs.  But
> that dies with:
>    Invalid set action mask read/0x0
> 
> The above mentioned file "devs" contains /etc/sdc1 ... /dev/sdn1 (12
> devices, one per line).
> 
> It generated 16 log files (it's a dual socket x quad core/8 thread intel
> CPUs).  The logs total 15M (using du --total -h *blktrace*).
> 
> blkparse reliably seg faults at around 102 seconds into the log:
>   8,209  1     5749   102.246254903  4825  U   N [(null)] 2
>   8,113  4    10445   102.255427790     0  C   R 14356151 + 8 [10445]
> Segmentation fault
> 
> Stderror does have some strange output:
> 
> # blkparse btrfs-12-blk.log > /dev/null
> Bad magic 0
> Bad magic 0
> Bad magic 0
> Bad magic 8
> Bad magic 0
> Bad magic 0
> Bad magic 0
> Bad magic c2d3ccfa
> Segmentation fault
> 
> It generated 61,758 lines of output when it dies.
> 
> Additional information about this machine, it's an ubuntu 11.04 x86-64
> machine with:
> # uname -a
> Linux fb 2.6.38-8-server #42-Ubuntu SMP Mon Apr 11 03:49:04 UTC 2011
> x86_64 x86_64 x86_64 GNU/Linux
> # blkparse --version
> blkparse version 1.0.1
> # blktrace --version
> blktrace version 2.0.0
> 
> This doesn't seem like a particularly challenging log to handle.
> 
> I looked for a way to tell blkparse to use a larger buffer but I didn't
> see a way to do that with blkparse --help or the blkparse man page.
> 
> Stupid user error?  Suggestions?  I'm sending it to this list as
> directed by the man page.
would you mind providing a tar.gz for the btrfs-12-blk.log?

Regards,
Tao