From: Eric Biggers <ebiggers3@gmail.com>
To: Theodore Ts'o <tytso@mit.edu>
Cc: fstests@vger.kernel.org, Amir Goldstein <amir73il@gmail.com>,
Eric Biggers <ebiggers@google.com>
Subject: Re: [PATCH] kvm-xfstests, gce-xfstests: improve recommended kernel config
Date: Mon, 22 May 2017 19:54:37 -0700 [thread overview]
Message-ID: <20170523025437.GA606@zzz> (raw)
In-Reply-To: <20170523021938.biqavccr6bdyy5sc@thunk.org>
Hi Ted,
On Mon, May 22, 2017 at 10:19:38PM -0400, Theodore Ts'o wrote:
> On Mon, May 22, 2017 at 10:24:20AM -0700, Eric Biggers wrote:
> > -CONFIG_LOCK_STAT=y
> > -CONFIG_DEBUG_LOCKDEP=y
>
> Lockdep has *definitely* found bugs for us, and so I don't think we
> want to turn it off. lockstat is a interesting case. It definitely
> can cause performance degredations, but it also can very find
> performance problems.
>
> I can definitely see us potentially looking for locking hotspots by
> using a DAX configuration (or a /dev/ram configuration) using a
> n1-highcpu-64 GCE VM. (Indeed, since Eric Whitney retired from HP,
> we've lost our only "big iron" system for doing scalability testing.)
>
> The test appliance does currently export /proc/lock_stat via the www
> interface, although we're currently not saving it in the results
> tar.gz file. (That's an oversight.)
>
> So I have a slight preferene for leaving LOCK_STAT enabled, even if
> we're not using most of the time. We're certainly not doing
> performance benchmarks using this config, at any rate!
>
DEBUG_LOCKDEP is for debugging lockdep itself, not for turning on lockdep
(that's CONFIG_PROVE_LOCKING). So I don't think it's needed.
I'm fine with leaving on LOCK_STAT; I didn't know there was interest in it.
Eric
next prev parent reply other threads:[~2017-05-23 2:54 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-22 17:24 [PATCH] kvm-xfstests, gce-xfstests: improve recommended kernel config Eric Biggers
2017-05-23 2:19 ` Theodore Ts'o
2017-05-23 2:54 ` Eric Biggers [this message]
2017-05-23 14:41 ` Theodore Ts'o
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