Date: Fri, 19 Feb 2010 19:39:01 +0100 From: Joerg Sonnenberger <joerg@britannica.bec.de> To: freebsd-hackers@freebsd.org Subject: Re: "tar tfv /dev/cd0" speedup patch Message-ID: <20100219183901.GA11388@britannica.bec.de> In-Reply-To: <4B7E1BA5.7050209@freebsd.org> References: <20100217215940.GA19713@triton8.kn-bremen.de> <4B7CE066.4030403@freebsd.org> <20100218183459.GA65508@triton8.kn-bremen.de> <20100218191347.GA4040@britannica.bec.de> <4B7E1BA5.7050209@freebsd.org>
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On Thu, Feb 18, 2010 at 09:03:33PM -0800, Tim Kientzle wrote: > Joerg Sonnenberger wrote: > >On Thu, Feb 18, 2010 at 07:34:59PM +0100, Juergen Lock wrote: > >> Ok here is a new version of the patch with these things fixed and the > >>Linux case added: (Linux case not tested yet, and yes I did this on > >>stable/8.) > > > >Why the check at all? Shouldn't devices that don't allow seek fail that? > >E.g. for devices, just try to seek ahead and fallback to normal reading? > > That was the initial implementation in libarchive, but > I had a number of reports of that not working for > tape drives. I recently dug out and connected an > old DDS drive I had in the closet, so I should > probably try again and see if I misunderstood > something along the way. I can think of some complications that for block devices the seek is to be a multiple of the block size (just like reads), but that's all I can think of in terms of portable problems. Joerg
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