RFR: 8079315: UseCondCardMark broken in conjunction with CMS precleaning
aph at redhat.com
Mon May 11 16:21:21 UTC 2015
On 05/11/2015 05:06 PM, Vitaly Davidovich wrote:
>> Also the global operation is not purely, but “mostly" locally expensive
>> for the thread performing the global fence. The cost on global CPUs is
>> pretty much simply a normal fence (roughly). Of course there is always
>> gonna be that one guy with 4000 CPUs which might be a bit awkward.
Well yes, but that guy with 4000 CPUs is precisely the target for
>> But even then, with high enough n, shared, timestamped global
>> fences etc, even such ridiculous scalability should be within
> Is it roughly like a normal fence for remote CPUs?
I would not think so. Surely you'd have to interrupt every core in
the process and do a bunch of flushes. A TLB flush is expensive, as
is interrupting the core itself. I'm fairly sure there's no way to
flush a remote core's TLB without interrupting it.
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