linux-kernel - Re: [PATCH 1/4] reduce kvm stack usage in kvm_arch_vm

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Message-ID: <48A18958.8060307@qumranet.com>
Date:	Tue, 12 Aug 2008 16:00:08 +0300
From:	Avi Kivity <avi@...ranet.com>
To:	Dave Hansen <dave@...ux.vnet.ibm.com>
CC:	Avi Kivity <avi@...o.co.il>, kvm-devel <kvm@...r.kernel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] reduce kvm stack usage in kvm_arch_vm_ioctl()

Dave Hansen wrote:
> On my machine with gcc 3.4, kvm uses ~2k of stack in a few
> select functions.  This is mostly because gcc fails to
> notice that the different case: statements could have their
> stack usage combined.  It overflows very nicely if interrupts
> happen during one of these large uses.
>
> This patch uses two methods for reducing stack usage.
> 1. dynamically allocate large objects instead of putting
>    on the stack.
> 2. Use a union{} member for all of the case variables. This
>    tricks gcc into combining them all into a single stack
>    allocation. (There's also a comment on this)
>
>   

Applied all, thanks.

-- 
error compiling committee.c: too many arguments to function

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