On Tue, 2006-02-28 at 11:25 +1100, Nick Piggin wrote:
> Chandra Seetharaman wrote:
>
> >On Mon, 2006-02-27 at 20:17 +1100, Nick Piggin wrote:
> >
> >>> #ifdef CONFIG_SCHEDSTATS
> >>>+
> >>>+int schedstats_sysctl = 0; /* schedstats turned off by default */
> >>>
> >>Should be read mostly.
> >>
> >>
> >>>+static DEFINE_PER_CPU(int, schedstats) = 0;
> >>>+
> >>>
> >>When the above is in the read mostly section, you won't need this at all.
> >>
> >>You don't intend to switch the sysctl with great frequency, do you?
> >>
> >
> >No, it is not expected to switch often.
> >
> >We originally coded it as __read_mostly, but thought the variable
> >bouncing between CPUs would be costly. Is it cheaper with
> >__read_mostly ? or it doesn't matter ?
> >
> >
>
> Well it will only "bounce" when the cacheline it is in is written to by
> a different CPU. Considering this happens with your per-cpu implementation
> _anyway_, they don't buy you anything much.
>
> Putting it in __read_mostly means that you won't happen to share a cacheline
> with a variable that is being written to frequently.
>
Thanks for the clarification Nick.
> Nick
>
> --
>
> Send instant messages to your online friends http://au.messenger.yahoo.com
>
>
>
> -------------------------------------------------------
> This SF.Net email is sponsored by xPML, a groundbreaking scripting language
> that extends applications into web and mobile media. Attend the live webcast
> and join the prime developer group breaking into this new coding territory!
> http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642
> _______________________________________________
> Lse-tech mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/lse-tech
-
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/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
