On 07/27/2011 09:33 PM, Andrew Lutomirski wrote:
> On Sandy Bridge, a null vsyscall takes 373 ns. Without
> VCGF_in_syscall, it's 457 ns. The change causes my little test app to
> get cs == __USER_CS.
Hm, 20% is more noticable than I would hope. What about a regular syscall?
> I suspect that Sandy Bridge is just about the worst case. syscall and
> sysret are amazingly fast on Sandy Bridge.
>
Yes, and one presumes it would only get worse.
J
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|