[Lustre-discuss] [zfs-discuss] ZFS/Lustre echo 0 >> max_cached_mb chewing 100% cpu

Lee, Brett brett.lee at intel.com
Tue Oct 22 12:01:47 PDT 2013


Andrew,

If I recall correctly, "FSTYPE=zfs /usr/lib64/lustre/tests/llmount.sh" will create and start a sample ZFS-backed Lustre file system using loopback devices.

Could you please check to see if there are loopback devices mounted as Lustre storage targets?  If so, unmounting these and stopping the Lustre file system should (could?) clean things up.

--
Brett Lee
Sr. Systems Engineer
Intel High Performance Data Division


> -----Original Message-----
> From: lustre-discuss-bounces at lists.lustre.org [mailto:lustre-discuss-
> bounces at lists.lustre.org] On Behalf Of Andrew Holway
> Sent: Tuesday, October 22, 2013 10:44 AM
> To: zfs-discuss at zfsonlinux.org
> Cc: lustre-discuss at lists.lustre.org
> Subject: Re: [Lustre-discuss] [zfs-discuss] ZFS/Lustre echo 0 >> max_cached_mb
> chewing 100% cpu
> 
> On 22 October 2013 16:21, Prakash Surya <surya1 at llnl.gov> wrote:
> > This probably belongs on the Lustre mailing list.
> 
> I cross posted :)
> 
> > Regardless, I don't
> > think you want to do that (do you?). It'll prevent any client side
> > caching, and more importantly, I don't think it's a case that's been
> > tested/optimized. What're you trying to acheive?
> 
> Sorry I was not clear, I didn't action this and I cant kill the process. It seemed to
> start directly after running:
> 
> "FSTYPE=zfs /usr/lib64/lustre/tests/llmount.sh"
> 
> I have tried to kill it first with -2 upto -9 but the process will not budge.
> 
> Here is the top lines from perf top
> 
> 37.39%  [osc]              [k] osc_set_info_async
>  27.14%  [lov]              [k] lov_set_info_async
>   4.13%  [kernel]           [k] kfree
>   3.57%  [ptlrpc]           [k] ptlrpc_set_destroy
>   3.14%  [kernel]           [k] mutex_unlock
>   3.10%  [lustre]           [k] ll_wr_max_cached_mb
>   3.00%  [kernel]           [k] mutex_lock
>   2.82%  [ptlrpc]           [k] ptlrpc_prep_set
>   2.52%  [kernel]           [k] __kmalloc
> 
> Thanks,
> 
> Andrew
> 
> >
> > Also, just curious, where's the CPU time being spent? What process
> > and/or kernel thread? What are the top entries listed when you run "perf
> top"?
> >
> > --
> > Cheers, Prakash
> >
> > On Tue, Oct 22, 2013 at 12:53:44PM +0100, Andrew Holway wrote:
> >> Hello,
> >>
> >> I have just setup a "toy" lustre setup using this guide here:
> >> http://zfsonlinux.org/lustre and have this process chewing 100% cpu.
> >>
> >> sh -c echo 0 >>
> >> /proc/fs/lustre/llite/lustre-ffff88006b0c7c00/max_cached_mb
> >>
> >> Until I get something more beasty I am using my desktop machine with
> >> KVM. Using standard Centos 6.4 with latest kernel. (2.6.32-358.23.2).
> >> my machine has 2GB ram
> >>
> >> Any ideas?
> >>
> >> Thanks,
> >>
> >> Andrew
> >>
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> >
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