Re: unionfs makes -CURRENT very sluggish

From: Daichi GOTO <daichi_at_freebsd.org>
Date: Wed, 23 Apr 2008 14:14:13 +0900
Jeremie Le Hen wrote:
> Hi,
> 
> On Tue, Apr 22, 2008 at 10:34:35PM +0200, Jeremie Le Hen wrote:
>> I tried to compile lib/ncurses through unionfs.  It is utterly slow, no
>> matter I mount with noatime or not.
>>
>> Relevant mounts:
>> % /usr/src on /space/chroot/usr/src (nullfs, local, read-only)
>> % <above>:/space/chroot/usr/src.union on /space/chroot/usr/src (unionfs, local)
>>
>> % root:~# chroot /space/chroot
>> % root:/# cd /usr/src/
>> % root:/# make buildenv
>> % # cd lib/ncurses
>> % # time make
>>
>> Compile time without noatime:
>>      5089.47 real      1670.72 user      3364.89 sys
>>
>> Compile time with noatime:
>>      5083.22 real      1664.10 user      3369.22 sys
>>
>> Now if I remove the unionfs mount and just use nullfs:
>>       255.47 real       150.51 user        83.82 sys
>>
>>
>> As you can see, most of the time is spent in kernel.  I'm recompiling my
>> kernel with hwpmc right now in order to profile it.  Any other debug
>> hint would be welcome.
>>
>> FWIW, "while sleep 1 ; do date ; done" runs jerkily when unionfs is run:
>> Tue Apr 22 21:20:06 CEST 2008
>> Tue Apr 22 21:20:13 CEST 2008
>> Tue Apr 22 21:20:17 CEST 2008
>> Tue Apr 22 21:20:22 CEST 2008
>> Tue Apr 22 21:20:29 CEST 2008
>>
>> Whereas it runs smoothly without unionfs.
>>
>> I'll give the result of hwpmc ASAP.
> 
> I've upgraded to the latest -CURRENT and the problem went away.  Sorry
> for the noise.
> 
> Regards,

No problem :)  Thanks for your report!

-- 
   Daichi GOTO, http://people.freebsd.org/~daichi
Received on Wed Apr 23 2008 - 03:14:15 UTC

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