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Date: Mon, 03 Aug 2015 16:10:59 +0300
From: Andriy Gapon <avg@FreeBSD.org>
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To: Scott Long <scott4long@yahoo.com>
CC: src-committers@FreeBSD.org, svn-src-all@FreeBSD.org,
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Subject: Re: svn commit: r284297 - in head:
 cddl/contrib/opensolaris/cmd/lockstat sys/kern sys/sys
References: <201506121001.t5CA1PTm089721@svn.freebsd.org>
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On 26/07/2015 23:27, Scott Long wrote:
> 
>> On Jun 12, 2015, at 4:01 AM, Andriy Gapon <avg@FreeBSD.org> wrote:
>>
>> Author: avg
>> Date: Fri Jun 12 10:01:24 2015
>> New Revision: 284297
>> URL: https://svnweb.freebsd.org/changeset/base/284297
>>
>> Log:
>>  several lockstat improvements
>>
>>  0. For spin events report time spent spinning, not a loop count.
>>  While loop count is much easier and cheaper to obtain it is hard
>>  to reason about the reported numbers, espcially for adaptive locks
>>  where both spinning and sleeping can happen.
>>  So, it's better to compare apples and apples.
>>
> 
> This causes spinning to be exceptionally more expensive just by having
> KDTRACE_HOOKS enabled, whether or not Dtrace is actually in use.  It
> makes it undesirable to deploy with Dtrace by default since it impacts
> performance.  Is there a way to make the expensive collection optional,
> or only enable when dtrace is using the lockstat module?  Also have you
> seen the other recent performance complaint related to this commit?

Sorry for the trouble.  Commit https://svnweb.freebsd.org/changeset/base/285704
should have fixed the problem.  Could you please check if that's so?
Thanks.

-- 
Andriy Gapon