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Re: No documentation of -fsched-pressure-algorithm

From: nick clifton <nickc at redhat dot com>
To: richard dot sandiford at linaro dot org, gcc at gcc dot gnu dot org, rdsandiford at googlemail dot com
Date: Tue, 01 May 2012 09:37:05 +0100
Subject: Re: No documentation of -fsched-pressure-algorithm
References: <87sjfl5gc6.fsf@Gift.fritz.box> <878vhdxgnm.fsf@talisman.home>

Hi Richard,

   I have just noticed that the new -fsched-pressure-algorithm= gcc
   command line option is not documented in gcc/doc/invoke.texi.  Was
   this an oversight ?

No, it was deliberate. It's not supposed to be a user-level option.

Then why is there a user-visible command line option ?

Also - why shouldn't it be a user-level option ? In my experience gcc's instruction scheduling tends to be very sensitive to the algorithm being compiled. For some applications it does a good job, but for others it actually makes the performance worth. Being able to tune the behaviour of the scheduler (via the various -fsched-... options) has been very helpful in getting good benchmark results.

Cheers
  Nick

Follow-Ups:
- Re: No documentation of -fsched-pressure-algorithm
  - From: Richard Sandiford

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