Date: Sun, 24 Sep 2006 00:52:13 -0400 From: Kris Kennaway <kris@obsecurity.org> To: Tim Kientzle <tim@kientzle.com> Cc: Tim Kientzle <kientzle@freebsd.org>, Andre Oppermann <andre@freebsd.org>, current@FreeBSD.org, Kris Kennaway <kris@obsecurity.org> Subject: Re: bsdtar vs gtar performance Message-ID: <20060924045213.GA17506@xor.obsecurity.org> In-Reply-To: <45156E4E.6040806@kientzle.com> References: <200609150804.k8F84O1H056038@repoman.freebsd.org> <20060915155912.GA71796@xor.obsecurity.org> <450AD508.10608@freebsd.org> <20060915180315.GB74735@xor.obsecurity.org> <450C30ED.7090901@freebsd.org> <20060916192437.GA15425@xor.obsecurity.org> <45156E4E.6040806@kientzle.com>
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[Moving to current@ where it's on-topic]
On Sat, Sep 23, 2006 at 10:26:38AM -0700, Tim Kientzle wrote:
> Kris and Ruslan were recently discussing the performance of bsdtar
> relative to gtar, which prompted me to do some measurements
> of my own. I used /usr/ports as my test, because it stresses
> file and directory creation over extracting large files.
>
> Here are some initial results, based on ten runs of each test on a
> quiescent system, comparing results with PHK's "ministat":
>
> * Creating uncompressed archives: bsdtar and gtar showed
> no difference in total time.
>
> * Extracting gzip-compressed archives: bsdtar and gtar showed
> no difference in total time.
>
> * Extracting uncompressed archives: gtar is about 13% faster
> than bsdtar in my test. Interestingly (to me), this was the same
> with or without -m. (I've long suspected dir timestamp restores
> as a contributor; this shows otherwise.)
With 10 repetitions of an extraction of the ports tree to a
swap-backed md (newfs'ed in between tests, mounted async), I get a
much bigger difference in favour of gtar:
x gtar-data
+ bsdtar-data
+------------------------------------------------------------+
|x + |
|x + |
|xx + |
|xx ++ |
|xx ++ |
|xx ++++|
|A| A| |
+------------------------------------------------------------+
N Min Max Median Avg Stddev
x 10 34.9 35.2 34.985 35.008 0.095893459
+ 11 48.95 49.68 49.21 49.249091 0.19216943
Difference at 95.0% confidence
14.2411 +/- 0.141059
40.6795% +/- 0.402932%
(Student's t, pooled s = 0.154247)
I suspect you were measuring extraction on real disk hardware, in
which case you're mostly measuring overhead from the disk I/O, which
is going to make up most of the real time in both cases.
Kris
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