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From: Jeff King <peff@peff.net>
To: Stefan Beller <sbeller@google.com>
Cc: gennady.kupava@gmail.com, git <git@vger.kernel.org>,
	Gennady Kupava <gkupava@bloomberg.net>
Subject: Re: [PATCH] Reduce performance penalty for turned off traces
Date: Fri, 17 Nov 2017 17:16:31 -0500	[thread overview]
Message-ID: <20171117221631.x2xqeeqmf5xob3yv@sigill.intra.peff.net> (raw)
In-Reply-To: <CAGZ79kb4Eo0AC4Z42_ks5_+Pcy4DrDCufNb=5J=g8L6pMnHd7A@mail.gmail.com>

On Wed, Nov 15, 2017 at 11:14:20AM -0800, Stefan Beller wrote:

> > I did manually disable HAVE_VARIADIC_MACROS and confirmed that the
> > result builds and passes the test suite (though I suspect that GIT_TRACE
> > is not well exercised by the suite).
> 
> GIT_TRACE is exercised in the test suite (though I am not sure if it counts
> as well-exercised) in t7406-submodule-update.sh for example, which uses
> GIT_TRACE to obtain information about thread parallelism used by Git, as
> that is not observable otherwise, if we assume that performance tests in the
> standard test suite are not feasible.

Hmm, yeah, that might cover it. What I'm worried about is that we missed
some case where NULL needed to become &trace_default_key. But I did look
for that in my review of the patch and didn't notice any spots. And the
coverage in t7406 should help.

> > After your patch, the GIT_TRACE=1 time remains the same but GIT_TRACE=0
> > drops to 1ms.
> 
> So does that mean we can use a lot more tracing now?

Yep, that's the intent.

-Peff

  reply	other threads:[~2017-11-17 22:16 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-11 19:28 [PATCH] Reduce performance penalty for turned off traces gennady.kupava
2017-11-12 14:17 ` Jeff King
2017-11-12 23:24   ` Gennady Kupava
2017-11-17 22:12     ` Jeff King
2017-11-15 19:14   ` Stefan Beller
2017-11-17 22:16     ` Jeff King [this message]
2017-11-19  0:42       ` [PATCH 1/2] Simplify tracing code by removing trace key normalization concept gennady.kupava
2017-11-19  0:42         ` [PATCH 2/2] Reduce performance cost of the trace if trace category is disabled gennady.kupava
2017-11-19  8:27           ` Johannes Sixt
2017-11-19 13:18             ` Gennady Kupava
2017-11-19  2:19         ` [PATCH 1/2] Simplify tracing code by removing trace key normalization concept Junio C Hamano
2017-11-19 13:16           ` Gennady Kupava
2017-11-20  0:24             ` Junio C Hamano
2017-11-20  4:59               ` Junio C Hamano
2017-11-26 20:11                 ` [PATCH 1/2] trace: remove trace key normalization gennady.kupava
2017-11-26 20:11                   ` [PATCH 2/2] trace: improve performance while category is disabled gennady.kupava
2017-11-27  1:21                     ` Junio C Hamano
2017-11-27  1:32                       ` Junio C Hamano
2017-11-27  3:25                         ` Junio C Hamano
2017-11-27 10:12                           ` Gennady Kupava

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