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From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <CADiFPYJSjeXf_zO756vUcn6UMELQHYeW9kmCZ+ynDJstSuFHyQ@mail.gmail.com>
	(Peter Feiner's message of "Fri, 25 Nov 2011 14:02:39 -0500")
References: <CADiFPYJSjeXf_zO756vUcn6UMELQHYeW9kmCZ+ynDJstSuFHyQ@mail.gmail.com>
Date: Sun, 27 Nov 2011 23:43:42 +0100
Message-ID: <87ipm5uqxt.fsf@trasno.mitica>
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Subject: Re: [Qemu-devel] [PATCH] pc: map pc ram from user-specified file
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To: Peter Feiner <peter@gridcentric.ca>
Cc: aliguori@us.ibm.com, qemu-devel@nongnu.org

Peter Feiner <peter@gridcentric.ca> wrote:
> Enables providing a backing file for the PC's ram. The file is specified by the
> new -pcram-file option. The file is mmap'd shared, so the RAMBlock that it backs
> doesn't need to be saved by vm_save / migration.
>
> Signed-off-by: Peter Feiner <peter@gridcentric.com>

Hi

Do you have any performance number for this?  And examples on how your
are using it?

> +#ifdef __linux__
> +    new_block->host = mem_file_ram_alloc(new_block, size);
> +    if (new_block->host) {
> +        assert(!host);
> +    } else
> +#endif
>      if (host) {

This test is (at least suspicious).  Shouldn't we check first if host
is not NULL? (Not that I fully understand that part)

Thanks, Juan.