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Date: Fri, 3 Jun 2005 16:19:30 -0400
From: Christopher Faylor <cgf-no-personal-reply-please AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: memset & 'VirtualQuery'
Message-ID: <20050603201930.GD32209@trixie.casa.cgf.cx>
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References: <001701c56873$6a20f640$96cefea9 AT none>
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On Fri, Jun 03, 2005 at 09:35:35PM +0200, Christophe Jaillet wrote:
>[sorry for the wrong post in cygwin-patches...]
>
>when looking thrue cygwin code looking for function 'VirtualQuery', we can
>see that it is passed a structure (MEMORY_BASIC_INFORMATION).
>In some cases, this structure is memset'ed to 0 before the call, sometimes,
>not.
>
>My very own opinion about it, is that there is no need to reset the content
>of the structure before the call and in some places a call to memset can be
>avoided.
>
>Here is a list of the call to 'VirtualQuery' which uses memset and could be
>optimised :
>   - cygthread.cc (terminate_thread)
>   - fork.cc (stack_base)
>   - exceptions.cc (interruptible)
>
>All the other calls to 'VirtualQuery' don't use memset.
>
>If you think it is useful, I can provide a patch for this in the next few
>days.

All of the calls to VirtualQuery which first clear the
MEMORY_BASIC_INFORMATION structure do so for a reason -- it simplifies
subsequent inspection of that structure if you are assured that it is
all zero.

cgf

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