On Mon, May 08, 2006 at 12:07:54AM -0700, David S. Miller wrote:
> From: Pavel Machek <[email protected]>
> Date: Mon, 8 May 2006 06:26:05 +0000
>
> > > Then I'll run my test on one of the various arches where HZ=~100 and
> > > we don't have a TSC. Like Sparc?
> > >
> > > /* XXX Maybe do something better at some point... -DaveM */
> > > typedef unsigned long cycles_t;
> > > #define get_cycles() (0)
> >
> > Seems like sparc32 is broken :-(, and probably broken terminally...
> > there are very little randomness sources that can handle 10msec
> > sampling period :-(.
> >
> > Maybe we should disable /dev/random on sparc32?
>
> What do other platforms without a TSC do?
Using get_cycles() for /dev/random is new as of 2.6. Before that, we
were directly calling rdtsc on x86 alone. 10msec resolution is fine
for plenty of sources.
>From a brief glance, the following don't have a useful get_cycles:
v850, sh, sh64, h8300, m32r, arm, arm26, cris, frv, um, m68k, xtensa,
sparc
And several others like mips (and x86) have one on only some hardware.
--
Mathematics is the supreme nostalgia of our time.
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