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From Phillip Susi <ps...@cfl.rr.com>
Subject Re: Deleting the async-dev branch
Date Sun, 20 Nov 2005 21:34:27 GMT
Actually you have to use a peg revision, not -r.  If you try -r to look 
at the deleted branch, svn tries to find the named directory in the HEAD 
revision, then look up it's state as it existed in rev x.  This will 
fail since it does not exist in the head revision, so instead you have 
to do something like:

svn list http://repos/svn/deleted@x

svn list -r x http://repos/svn/deleted fails because deleted does not 
exist anymore.

By the way, what exactly is the async-dev branch and what are the future 
plans for it?  I actually have spent this entire weekend doing research 
on the current state of support of async IO in linux and modified the dd 
program to use overlapped async IO when you pass it the iflag=direct 
option.  It turned out that glibc's posix aio library simply performs 
sync IO in a background thread, so I ended up hacking together a basic 
aio implementation that directly uses the kernel's aio support.  I'm 
still testing it but it looks like it yielded substantial cpu savings 
and throughput increases by keeping the drive directly reading into the 
userspace buffers.  DMA transfers sure beat memcpy()s.

I have been a big proponent of zero copy async IO for several years now 
so I am very interested in projects to further it's support and use.

Max Bowsher wrote:
> 
> Definitely not!
> 
> You can always look at any deleted thing by looking back into the
> history with an appropriate svn --revision (-r) argument.
> 
> The only significant effect of deleting a branch is to unequivocally
> indicate to everyone that a branch's sole reason for existence is now
> historical record, rather than active development.
> 
> Max.
> 
> 
> 


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