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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--wac7ysb48OaltWcw Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable [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. >=20 > Here are some initial results, based on ten runs of each test on a > quiescent system, comparing results with PHK's "ministat": >=20 > * Creating uncompressed archives: bsdtar and gtar showed > no difference in total time. >=20 > * Extracting gzip-compressed archives: bsdtar and gtar showed > no difference in total time. >=20 > * 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 =3D 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 --wac7ysb48OaltWcw Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (FreeBSD) iD8DBQFFFg79Wry0BWjoQKURAvwCAJ0RZWyFmN7fD5GIVMi4WegoQM+u6QCfXKbP f1drVqPi6Nz2sBaWJqMfcFE= =+Ir/ -----END PGP SIGNATURE----- --wac7ysb48OaltWcw--
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