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Date: Fri, 28 Dec 2001 16:55:59 -0800
From: Larry McVoy <lm@bitmover.com>
To: Keith Owens <kaos@ocs.com.au>
Cc: Larry McVoy <lm@bitmover.com>, linux-kernel@vger.kernel.org,
        kbuild-devel@lists.sourceforge.net
Subject: Re: State of the new config & build system
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> I also want updates from the dependency back end code, to remove the
> phase 5 processing.  The "extract dependency" code runs after each
> compile step so there can be multiple updates running in parallel.  My
> gut feeling is that it will be faster to have one database server and
> all the back ends talk to that server.  Otherwise each compile will
> have overhead for lock, open, mmap, update, close, write back, unlock.
> A single threading server removes the need for lock/unlock and can sync
> the data to disk after n compiles instead of being forced to do it
> after every compile.
> 
> If your experience says that doing updates from each compile step
> without a server process would not be too slow, let me know.

You certainly don't need a server process.   And as was pointed out
earlier, it's nice not to have them, then you don't have to worry 
about them still being there.

I can write you up a multi writer version using in file locks (which
work over NFS, we had do that for BK and I'm pretty sure it is platform
independent, I can't break it).  We have to do this sort of multi
reader/writer crud in BK all the time and have lots of experience with
locking, breaking locks, waiting, NFS, etc.  Much more experience than
we ever wanted :-)

You don't need to sync to disk at all, let the data sit in memory, that's
why mmap is cool.

Give me a spec for what you want, I'll crank out some code.  Maybe I'll 
finally actually be useful to the kernel after all these years...
-- 
---
Larry McVoy            	 lm at bitmover.com           http://www.bitmover.com/lm 
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