Date: Fri, 30 May 2008 12:54:46 +0300 From: Diomidis Spinellis <dds@aueb.gr> To: Maxim Sobolev <sobomax@FreeBSD.org> Cc: Harti Brandt <harti@FreeBSD.org>, Andriy Gapon <avg@icyb.net.ua>, current@FreeBSD.org Subject: Re: cp(1) and mmap Message-ID: <483FCEE6.3030608@aueb.gr> In-Reply-To: <483F3AA2.8000601@FreeBSD.org> References: <20080528110003.Q24259@beagle.kn.op.dlr.de> <483D5DF8.4020504@icyb.net.ua> <483F1559.2020600@aueb.gr> <483F3AA2.8000601@FreeBSD.org>
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Maxim Sobolev wrote: >> I also think we should use mmap for larger files, mmapping and writing >> them out in several chunks. > > I believe that even better way is to extend sendfile(2) to allow both > sockets and file descriptors to be used as the destination and use that > interface instead of mmap/read/write. Linux for example allows that. Sounds like a good idea. Linux's sendfile documents this behavior: "sendfile() copies data between one file descriptor and another.", but then mentions it is not currently implemented: "Presently (Linux 2.6.9): in_fd, must correspond to a file which supports mmap()-like operations (i.e., it cannot be a socket); and out_fd must refer to a socket." Solaris documents it and supports it: "The in_fd argument should be a file descriptor to a regular file opened for reading. See open(2). The out_fd argument should be a file descriptor to a regular file opened for writing or to a connected AF_INET or AF_INET6 socket of SOCK_STREAM type." I will look at it after fixing the more pressing cp(1) bug. Diomidis
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