Date: Fri, 14 Mar 2008 23:36:53 +0100 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: Alfred Perlstein <alfred@freebsd.org> Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, Diomidis Spinellis <dds@FreeBSD.org>, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/tools/regression/bin/mv regress.sh Message-ID: <20080314223652.GA20470@garage.freebsd.pl> In-Reply-To: <20071218100355.GR16982@elvis.mu.org> References: <200712180849.lBI8nmEi088947@repoman.freebsd.org> <20071218100355.GR16982@elvis.mu.org>
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[-- Attachment #1 --] On Tue, Dec 18, 2007 at 02:03:55AM -0800, Alfred Perlstein wrote: > * Diomidis Spinellis <dds@FreeBSD.org> [071218 00:48] wrote: > > dds 2007-12-18 08:49:47 UTC > > > > FreeBSD src repository > > > > Modified files: > > tools/regression/bin/mv regress.sh > > Log: > > Add more tests. All rename(2)-based tests now succeed. > > The performance of the cross-device equivalents is under investigation. > > Diomidis, > > Does 'mv' spawn off tar or something to do the copy part? > > You can _usually_ get much better cross device performance > by hooking two processes together like so: > > tar -cf - -C /path/to/source . | tar -xf - -C /path/to/dst > > This will keep the disks a lot busier, but this can make > things worse on cross device moves that happen to be > on the same disk. I was thinking about adding two options to cp(1) (-1 and -2) to give cp(1) a hint if the copy is done inside one disk or between separate disks. In -1 case cp(1) will read as large blocks as possible and then write them, in -2 case it will spawn two threads: one reader and one writer working in parallel. Performance improvements are very visible from what I tested. -- Pawel Jakub Dawidek http://www.wheel.pl pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) iD8DBQFH2v4DForvXbEpPzQRAlOZAKDk2+7pUbFJrOSyT/9LOId4SUkK5ACglNJz 8bjfDo0b4T1TWtph4p8ZzoY= =KLyk -----END PGP SIGNATURE-----
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