Date: Mon, 03 Aug 2015 16:10:59 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Scott Long <scott4long@yahoo.com> Cc: src-committers@FreeBSD.org, svn-src-all@FreeBSD.org, svn-src-head@FreeBSD.org Subject: Re: svn commit: r284297 - in head: cddl/contrib/opensolaris/cmd/lockstat sys/kern sys/sys Message-ID: <55BF6863.8000103@FreeBSD.org> In-Reply-To: <FD6800E2-C392-4071-9CC5-D00876600F63@yahoo.com> References: <201506121001.t5CA1PTm089721@svn.freebsd.org> <FD6800E2-C392-4071-9CC5-D00876600F63@yahoo.com>
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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
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