Re: [Bloat] Hardware upticks

[David Collier-Brown <davec-b@rogers.com>]

The SPARC T5 is surprisingly good here, with a very short path to cache 
and a moderate number of threads with hot cache lines.  Cache 
performance was one of the surprises when the slowish early T-machines 
came out, and surprised a smarter colleague and I who had apps 
bottlenecking on cold cache lines on what were nominally much faster 
processors.

I'd love to have a T5-1 on an experimenter board, or perhaps even in my 
laptop (I used to own a SPARC laptop), but that's not where Snoracle is 
going.

--dave

On 05/01/16 02:37 PM, Dave Täht wrote:
>
> On 1/5/16 11:29 AM, Steinar H. Gunderson wrote:
>> On Tue, Jan 05, 2016 at 10:57:13AM -0800, Dave Täht wrote:
>>> Context switch time is probably one of the biggest hidden nightmares in
>>> modern OOO cpu architectures - they only go fast in a straight line. I'd
>>> love to see a 1ghz processor that could context switch in 5 cycles.
>> It's called hyperthreading? ;-)
>>
>> Anyway, the biggest cost of a context switch isn't necessarily the time used
>> to set up registers and such. It's increased L1 pressure; your CPU is now
>> running different code and looking at (largely) different data.
> +10.
>
> A L1/L2 Icache dedicated to interrupt processing code could make a great
> deal of difference, if only cpu makers and benchmarkers would make
> CS time something we valued.
>
> Dcache, not so much, except for the intel architectures which are now
> doing DMA direct to cache. (any arms doing that?)
>
>> /* Steinar */
>>
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-- 
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
davecb@spamcop.net           |                      -- Mark Twain