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Re: fc3 and stacks

To: Eric Sandeen <sandeen@xxxxxxx>
Subject: Re: fc3 and stacks
From: Lonni J Friedman <netllama@xxxxxxxxxxxxx>
Date: Mon, 14 Mar 2005 15:20:21 -0500 (EST)
Cc: linux-xfs@xxxxxxxxxxx
In-reply-to: <4235F824.6070303@sgi.com>
References: <20050310232036.GA19295@lemming.cita.utoronto.ca> <4234E903.8010309@thebarn.com> <4235D44F.1020902@tippett.com> <20050314190915.GB9784@lemming.cita.utoronto.ca> <4235F824.6070303@sgi.com>
Sender: linux-xfs-bounce@xxxxxxxxxxx
On Mon, 14 Mar 2005, Eric Sandeen wrote:
> Robin Humble wrote:
>
> > Some ways forward:
> >  - convince RedHat to put 8k stacks (or at least the option for it) and
> >    XFS into AS4.
>
> FWIW, I try to steer the conversation away from "xfs is broken with 4k
> stacks" and towards "4k stacks don't work for some applications."  :)
>
> XFS can chew through stack a bit faster than some of the filesystems, to
> be sure.  But I've always meant to try to put together some diabolical
> "supported" config on RHEL4 and file a bug - say nfs over deeply nested
> volume managers, or something like that.
>
> >  - try to make XFS play nicer with 4k stacks
> >  - run fc3. fc3 and AS4 are very similar (~ 50% of userland rpms are
> >    identical, the rest seem to be fairly minor variations), so if your
> >    vendor supports AS4 then it'll almost certainly run fine on fc3
>
> but both fc3 and RHEL4 have 4k stacksm though...
>
> >  - install AS4 but run a fc3 (recompiled for 8k stacks) kernel
>
> ...ah, yes.
>
> >  - install AS4 but run a stock kernel.org (or XFS cvs) kernel
>
> Seems like with RHEL3, stock kernel.org kernels don't play nicely.  I
> hope this isn't the case with RHEL4, but I have not tested it.

That's not the case across the board.  I'm running a stock kernel.org 2.6
kernel on RHEL3 (for almost a year now) and haven't had any problems.
Perhaps i've not hit whatever issue you've experienced?

> > The first 2 of these are hard, the last 2 are pretty easy but may not
> > help you from a vendor support point of view. We'll probably choose the
> > last option.
> > The middle option (fc3) is what you are doing now, so you can get some
> > idea of XFS stability with 4k stacks for your particular workload.
> >
> > I wonder why RedHat was so keen to remove 8k as an option. Things would
> > be fairly simple if they hadn't done that.
>
> I think there are some applications (java?) that can benefit from
> smaller stacks in terms of overal thread count & memory usage...  but I
> don't know why they went so far as to actually remove the option.

Could be.  The RHEL3 boxes where i'm running a 2.6.x kernel are also
running JBoss.

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Lonni J Friedman                        netllama@xxxxxxxxxxxxx
LlamaLand                               http://netllama.linux-sxs.org


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