Keith's the expert (who wrote the smart scheduler): I'd take a wild ass
guess that 10ms is good enough.
Maybe people can keep him on the cc list this time...
- Jim
On Tue, 2006-07-25 at 14:18 -0700, H. Peter Anvin wrote:
> Jim Gettys wrote:
> > On Tue, 2006-07-25 at 14:04 -0700, H. Peter Anvin wrote:
> >
> >> That's why I'm suggesting adding a cheap, possibly low-res, gettimeofday
> >> virtual system call in case there is no way for the kernel to provide
> >> userspace with a cheap full-resolution gettimeofday. Obviously, if a
> >> high-quality gettimeofday is available, then they can be linked together
> >> by the kernel.
> >
> > Low res is fine: X Timestamps are 1 millisecond values, and wrap after a
> > few hundred days. What we do care about is monotonically increasing
> > values (until it wraps). On machines of the past, this was very
> > convenient; we'd just store a 32 bit value for clients to read, and not
> > bother with locking. I guess these days, you'd at least have to protect
> > the store with a memory barrier, maybe....
> >
> > It was amusing years ago to find toolkit bugs after applications had
> > been up for that long (32 bits of milliseconds)... Yes, there are
> > applications and machines that stay up that long, really there are....
> >
>
> Do you need 1 ms resolution, or is 10 ms good enough?
>
> -hpa
>
--
Jim Gettys
One Laptop Per Child
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
- Follow-Ups:
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: Thomas Gleixner <[email protected]>
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: Bill Huey (hui) <[email protected]>
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- References:
- [PATCH] RTC: Add mmap method to rtc character driver
- From: Neil Horman <[email protected]>
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: Segher Boessenkool <[email protected]>
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: Neil Horman <[email protected]>
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: "H. Peter Anvin" <[email protected]>
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: Neil Horman <[email protected]>
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: Segher Boessenkool <[email protected]>
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: Neil Horman <[email protected]>
- Re: Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: "Dave Airlie" <[email protected]>
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: "H. Peter Anvin" <[email protected]>
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: Neil Horman <[email protected]>
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: Jim Gettys <[email protected]>
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: "H. Peter Anvin" <[email protected]>
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: Jim Gettys <[email protected]>
- Re: [PATCH] RTC: Add mmap method to rtc character driver
- From: "H. Peter Anvin" <[email protected]>
- [PATCH] RTC: Add mmap method to rtc character driver
- Prev by Date: Re: [PATCH] mm: inactive-clean list
- Next by Date: Re: [PATCH] TIF_NOTSC and SECCOMP prctl
- Previous by thread: Re: [PATCH] RTC: Add mmap method to rtc character driver
- Next by thread: Re: [PATCH] RTC: Add mmap method to rtc character driver
- Index(es):
 |