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From: Jeff King <peff@peff.net>
To: Taylor Blau <me@ttaylorr.com>
Cc: git@vger.kernel.org, dstolee@microsoft.com
Subject: Re: [PATCH 1/1] commit-graph.c: avoid unnecessary tag dereference when merging
Date: Tue, 24 Mar 2020 02:06:37 -0400	[thread overview]
Message-ID: <20200324060637.GB610977@coredump.intra.peff.net> (raw)
In-Reply-To: <20200322164531.GA55067@syl.local>

On Sun, Mar 22, 2020 at 10:45:31AM -0600, Taylor Blau wrote:

> So, I'm not sure what was going on with my original measurements, other
> than that I took them around midnight, so the chance for error was
> probably high. I'll go with your measurements, since they are both
> closer to what we'd see in the real world, and actually representative
> of the change here.

I wondered if perhaps you had stray commit-graph files sitting around. I
don't think we'd look at them if they aren't mentioned in the
commit-graphs index, though. And anyway, feeding all of the packed
objects would mean those would all be parsed in the earlier stage, so
even if we _did_ have a bunch of stuff to merge, it would have been fast
even with the old code.

So...I dunno.

One other thing that's bitten me in the past is accidentally compiling
with the wrong optimization settings. I have my config.mak set up to
compile with -O0 by default (because it's faster and because I'm
frequently debugging anyway), and then I do a -O2 build for my daily
driver. But when performance testing, I sometimes accidentally compare
-O0 and -O2 builds to each other. That's all very specific to my
config.mak setup, but I know you've picked up some of it, so it's
possible you inherited that subtlety. :)

-Peff

  reply	other threads:[~2020-03-24  6:06 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-21  3:44 [PATCH 0/1] commit-graph: avoid unnecessary tag deference when merging Taylor Blau
2020-03-21  3:44 ` [PATCH 1/1] commit-graph.c: avoid unnecessary tag dereference " Taylor Blau
2020-03-21  5:00   ` Jeff King
2020-03-21  6:11     ` Taylor Blau
2020-03-21  6:24       ` Taylor Blau
2020-03-21  7:03       ` Jeff King
2020-03-21 17:27         ` Taylor Blau
2020-03-22  5:36           ` Jeff King
2020-03-22 11:04             ` SZEDER Gábor
2020-03-22 18:45               ` looking up object types quickly, was " Jeff King
2020-03-22 19:18                 ` Jeff King
2020-03-23 20:15               ` Taylor Blau
2020-03-22 16:45             ` Taylor Blau
2020-03-24  6:06               ` Jeff King [this message]
2020-03-21 18:50         ` Junio C Hamano
2020-03-22  0:03           ` Derrick Stolee
2020-03-22  0:20             ` Taylor Blau
2020-03-22  0:23               ` Derrick Stolee
2020-03-22  5:49                 ` Jeff King
2020-03-22  6:04                   ` Jeff King
2020-03-22 15:47                     ` Taylor Blau
2020-03-24  6:11                       ` Jeff King
2020-03-24 23:08                         ` Taylor Blau
2020-03-27  8:42                           ` Jeff King
2020-03-27 15:03                             ` Taylor Blau
2020-03-22 15:44                   ` Taylor Blau
2020-03-24  6:14                     ` Jeff King
2020-03-21  5:01   ` Junio C Hamano
2020-03-21  4:56 ` [PATCH 0/1] commit-graph: avoid unnecessary tag deference " Junio C Hamano
2020-03-21  5:04   ` Jeff King
2020-03-21  6:12     ` Taylor Blau

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