From: Peter Zijlstra <peterz@infradead.org>
To: Babu Moger <babu.moger@oracle.com>
Cc: mingo@redhat.com, akpm@linux-foundation.org,
keescook@chromium.org, dan.j.williams@intel.com,
aryabinin@virtuozzo.com, tj@kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/2] Ajust lockdep static allocations
Date: Fri, 23 Sep 2016 16:34:13 +0200 [thread overview]
Message-ID: <20160923143413.GM5008@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <df54eb77-2aad-7801-9ddc-bc085f03d246@oracle.com>
On Fri, Sep 23, 2016 at 09:04:42AM -0500, Babu Moger wrote:
> On 9/23/2016 2:12 AM, Peter Zijlstra wrote:
> >On Thu, Sep 22, 2016 at 11:43:34AM -0700, Babu Moger wrote:
> >>These patches adjust the static allocations for lockdep
> >>data structures used for debugging locking correctness. The current
> >>code reserves about 4MB extra space for these data structures. Most
> >>of the configurations do not need these many data structures. While
> >>testing, I have not seen it go beyond 20% of already reserved entries.
> >>
> >>$grep "lock-classes" /proc/lockdep_stats
> >> lock-classes: 1560 [max: 8191]
> >>
> >>Reserving even more space seems unreasonable. So, keeping the default
> >>entries small as before the Commit 1413c0389333 ("lockdep: Increase static
> >>allocations"). Added new CONFIG_PROVE_LOCKING_PLUS in case someone
> >>needs more entries to debug their large configuration.
> >Why make this more complicated? There's absolutely no upside to this
> >change as far as I can see.
> Peter, What do you mean?
I mean I see no point to the patches you send.
> Revert the commit 1413c038933?
Nah, why would I?
> Right now, I cannot boot my setup after enabling lockdep. How do you
> think we can handle this?
Why can't you boot? You have that little memories? 4MB doesn't seem like
a worthwhile amount of memory.
Also, you didn't say. This seems a somewhat crucial point.
In any case, maybe invert this, add make it depend on CONFIG_BASE_SMALL,
since this really only matters for really dinky systems.
next prev parent reply other threads:[~2016-09-23 14:34 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-22 18:43 Babu Moger
2016-09-22 18:43 ` [PATCH 1/2] lockdep: Keep the default static allocations small Babu Moger
2016-09-22 18:43 ` [PATCH 2/2] config: Add new CONFIG_PROVE_LOCKING_PLUS Babu Moger
2016-09-23 7:12 ` [PATCH 0/2] Ajust lockdep static allocations Peter Zijlstra
2016-09-23 14:04 ` Babu Moger
2016-09-23 14:34 ` Peter Zijlstra [this message]
2016-09-23 14:50 ` Babu Moger
2016-09-23 15:04 ` Peter Zijlstra
2016-09-23 15:15 ` Babu Moger
2016-09-23 15:40 ` Peter Zijlstra
2016-09-23 19:57 ` Babu Moger
2016-09-23 20:08 ` Rob Gardner
2016-09-23 20:17 ` Peter Zijlstra
2016-09-23 20:30 ` Babu Moger
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