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RE: [Xen-devel] Reducing impact of save/restore/dump on Dom0

To: "John Levon" <levon@xxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Reducing impact of save/restore/dump on Dom0
From: "Graham, Simon" <Simon.Graham@xxxxxxxxxxx>
Date: Tue, 6 Feb 2007 12:25:53 -0500
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Thread-topic: [Xen-devel] Reducing impact of save/restore/dump on Dom0
Thanks for the comments:

> 
> +#ifndef O_DIRECT
> +#define O_DIRECT 040000
> +#endif
> 
> O_DIRECT doesn't exist on Solaris. The closest equivalent is
> directio(fd, DIRECTIO_ON). Either way you shouldn't be defining it
> yourself?
> 

Well, I would agree with you except that it ends up not being defined
when I build on RHEL4/U2! It seems to me that O_DIRECT is something that
folks really don't want me to be able to use! 

Anyone know of a generic mechanism that works everywhere for enabling
this? If not, I guess I'll have to add #ifdef's... yuck! What I can do
is fix the problem on Linux and make it behave the same old way on
everything else (that I can't build/test for)... other people can then
add platform specific implementations as needed...

> And you should expect this to be able to fail, on Solaris at least.
> 
> +    dump_mem_start = mmap(0, PAGE_SIZE*DUMP_INCREMENT,
> +                          PROT_READ|PROT_WRITE,
> +                          MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
> 
> Please use the more portable MAP_ANON.
> 

Will do.

Simon

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