Re: [PATCH 3/3] index-pack: adjust default threading cap

From: Eric Sunshine <sunshine@sunshineco.com>
To: Jeff King <peff@peff.net>
Cc: "brian m. carlson" <sandals@crustytoothpaste.net>, git@vger.kernel.org
Subject: Re: [PATCH 3/3] index-pack: adjust default threading cap
Date: Mon, 24 Aug 2020 13:55:47 -0400	[thread overview]
Message-ID: <20200824175547.GA9245@flurp.local> (raw)
In-Reply-To: <20200824173735.GA673908@coredump.intra.peff.net>

On Mon, Aug 24, 2020 at 01:37:35PM -0400, Jeff King wrote:
> So I'd be very happy if people on other platforms (especially non-intel
> ones) wanted to run:
> 
>   cd t/perf
>   GIT_PERF_EXTRA=1 \
>   GIT_PERF_LARGE_REPO=/path/to/clone/of/linux.git \
>   ./p5302-pack-index.sh
> 
> and report the results.
> 
> I do have a slightly-old AMD machine with 4 cores (an A8-7600). Here's
> what it says:
> 
>   5302.3: index-pack 0 threads                   447.67(436.62+6.57)
>   5302.4: index-pack 1 threads                   450.80(441.26+7.20)
>   5302.5: index-pack 2 threads                   265.62(459.56+7.30)
>   5302.6: index-pack 4 threads                   177.06(477.56+8.22)
>   5302.7: index-pack default number of threads   202.60(473.15+7.61)

I tested on my 9.5 year old 4-core iMac with 2.5 GHz Intel Core i5,
spinning platter hard disk, and 12 GB memory (recently upgraded from 4
GB). I used git.git rather than linux.git because I didn't want to
wait several days for the results (plus this is my primary machine
which I'm actively using). Results were similar to what you saw:

  5302.3: index-pack 0 threads                   14.85(14.10+0.66)
  5302.4: index-pack 1 threads                   14.65(13.83+0.63)
  5302.5: index-pack 2 threads                   9.11(14.40+0.80) 
  5302.6: index-pack 4 threads                   6.89(17.03+1.32) 
  5302.7: index-pack default number of threads   7.72(16.15+1.15) 

Thanks for providing exact instructions for running the test; I had
never done it before, thus didn't know how.