On 06/21/2007 12:08 PM, Ingo Molnar wrote:
> yeah - i'm not at all arguing in favor of the BTRL patch i did: i always
> liked the 'nicer' inner loop of spinlocks, which could btw also easily
> use MONITOR/MWAIT.
The "nice" inner loop is necessary or else it would generate huge amounts
of bus traffic while spinning.
> So it seems the problem was that if a core kept _truly_ modifying a
> cacheline via atomics in a high enough frequency, it could artificially
> starve the other core. (which would keep waiting for the cacheline to be
> released one day, and which kept the first core from ever making any
> progress) To me that looks like a real problem on the hardware side -
> shouldnt cacheline ownership be arbitrated a bit better than that?
>
A while ago I showed that spinlocks were a lot more fair when doing
unlock with the xchg instruction on x86. Probably the arbitration is all
screwed up because we use a mov instruction, which while atomic is not
locked.
-
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]
