On Nov 17, 2011, at 12:55 PM, Juergen Lock wrote: >> >> After a few experiments, bsdtar stopped using lseek() on >> FreeBSD for anything other than regular files and block >> devices. I believe there are other things that do support >> seeking, but I don't believe there is an accurate mechanism >> for determining whether lseek() is correctly supported. > > Ah is that the reason why my patch never made it into FreeBSD 9? > I'm talking about this thread, where I also commented on seeking > on tape: > > http://docs.freebsd.org/cgi/mid.cgi?20100220101724.GA26604 > (Re: "tar tfv /dev/cd0" speedup patch) > > entire thread here: > http://markmail.org/message/nfznipqik3tuhbqp > > Cheers, > Juergen (who would still like to see a faster "tar tfv /dev/cd0"... :)
I would like to see that as well. Take a look at http://libarchive.googlecode.com/svn/trunk/libarchive/archive_read_open_filename.c Especially the comments about detecting "disk-like" devices. I rewrote a bunch of this code to introduce an explicit notion of "strategy" so that we could optimize access to a variety of different devices. This code has a notion of "disk-like" file descriptors and some optimizations for such. There are some comments in there outlining similar optimizations that could be made for "tape-like" or "socket-like" devices. Cheers, Tim _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[email protected]"
