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Date:      Sun, 2 Jan 2000 03:50:58 +0200 (EET)
From:      Michael Widenius <monty@monty.pp.sci.fi>
To:        Leif Neland <leif@neland.dk>
Cc:        Paul DuBois <paul@snake.net>, mysql@lists.mysql.com, freebsd-current@freebsd.org
Subject:   Re: 2 hours to compile mysql?
Message-ID:  <14446.44802.533912.420861@monty.pp.sci.fi>
In-Reply-To: <Pine.BSF.4.05.10001020005001.55763-100000@arnold.neland.dk>
References:  <14446.19685.932082.417212@monty.pp.sci.fi> <Pine.BSF.4.05.10001020005001.55763-100000@arnold.neland.dk>

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>>>>> "Leif" == Leif Neland <leif@neland.dk> writes:

>> The reason for this is that some gcc optimizations stages takes
>> exponentially more memory when compiling big functions.
>> bison produces one big function for the grammar parsing and its
>> this that takes a long time to compile;  To compile sql_yacc.cc quickly
>> on Intel, you nead at least 160M of free ram.  On a PentiumII 400mz with 256M
>> ram, it takes 11 seconds to compile sql_yacc.o.  Having to use swap
>> can easily make things 1000 times slower
>> 

Leif> Is amount of ram available (portably) to configure?

I don't think thats easy to check for..

Aother problem is also that even if you have only little ram, you
may still want to compile MySQL without --low-memory, because the
final code is much better if you don't have to use --low-memory.

Leif> So configure could decide to use --low-memory by itself? Allowing
Leif> overrides, naturally.

Leif> Leif

Regards,
Monty


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