Date: Tue, 2 Oct 2012 08:36:34 +0200 From: Yamagi Burmeister <lists@yamagi.org> To: tim@kientzle.com Cc: freebsd-hackers@freebsd.org, bfalk_bsd@brandonfa.lk Subject: Re: SMP Version of tar Message-ID: <20121002083634.3103fe958508a4026384ac96@yamagi.org> In-Reply-To: <87549776-9051-4B4B-8D53-DAE6D51C2A94@kientzle.com> References: <5069C9FC.6020400@brandonfa.lk> <87549776-9051-4B4B-8D53-DAE6D51C2A94@kientzle.com>
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--Signature=_Tue__2_Oct_2012_08_36_34_+0200_EDLuBl3TxLr/FPZX Content-Type: text/plain; charset=US-ASCII Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, 1 Oct 2012 22:16:53 -0700 Tim Kientzle <tim@kientzle.com> wrote: > There are a few different parallel command-line compressors and decompres= sors in ports; experiment a lot (with large files being read from and/or wr= itten to disk) and see what the real effect is. In particular, some decomp= ression algorithms are actually faster than memcpy() when run on a single p= rocessor. Parallelizing such algorithms is not likely to help much in the = real world. >=20 > The two popular algorithms I would expect to benefit most are bzip2 compr= ession and lzma compression (targeting xz or lzip format). For decompressi= on, bzip2 is block-oriented so fits SMP pretty naturally. Other popular al= gorithms are stream-oriented and less amenable to parallelization. >=20 > Take a careful look at pbzip2, which is a parallelized bzip2/bunzip2 impl= ementation that's already under a BSD license. You should be able to get a= lot of ideas about how to implement a parallel compression algorithm. Bet= ter yet, you might be able to reuse a lot of the existing pbzip2 code. >=20 > Mark Adler's pigz is also worth studying. It's also license-friendly, an= d is built on top of regular zlib, which is a nice technique when it's feas= ible. Just a small note: There's a parallel implementation of xz called "pixz". It's build atop of liblzma and libarchiv and stands under a=20 BSD style license. See: https://github.com/vasi/pixz Maybe it's possible to reuse most of the code. --=20 Homepage: www.yamagi.org XMPP: yamagi@yamagi.org GnuPG/GPG: 0xEFBCCBCB --Signature=_Tue__2_Oct_2012_08_36_34_+0200_EDLuBl3TxLr/FPZX Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (FreeBSD) iEYEARECAAYFAlBqi3cACgkQWTjlg++8y8u5uwCfWMSoOYdxB2ZDV+qDbfEX3z76 6kcAn0bJRHV47a4i2po55UTQKnrXBulb =fMmx -----END PGP SIGNATURE----- --Signature=_Tue__2_Oct_2012_08_36_34_+0200_EDLuBl3TxLr/FPZX--
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