From: Stephen Hemminger <stephen@networkplumber.org>
To: "Dave Täht" <dave@taht.net>
Cc: bloat@lists.bufferbloat.net
Subject: Re: [Bloat] Hardware upticks
Date: Tue, 5 Jan 2016 12:27:03 -0800 [thread overview]
Message-ID: <20160105122703.516b54be@xeon-e3> (raw)
In-Reply-To: <568C1B5E.1070008@taht.net>
On Tue, 5 Jan 2016 11:37:02 -0800
Dave Täht <dave@taht.net> 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 */
> >
> _______________________________________________
> Bloat mailing list
> Bloat@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/bloat
Intel has some new Cache QoS stuff that allows configuring how much
cache is allowed per context. But of course it is only on the newest/latest/unoptinium
next prev parent reply other threads:[~2016-01-05 20:26 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-05 6:37 Jonathan Morton
2016-01-05 17:42 ` Aaron Wood
2016-01-05 18:27 ` Jonathan Morton
2016-01-05 18:57 ` Dave Täht
2016-01-05 19:29 ` Steinar H. Gunderson
2016-01-05 19:37 ` Dave Täht
2016-01-05 20:13 ` David Collier-Brown
2016-01-05 20:27 ` Stephen Hemminger [this message]
2016-01-05 21:10 ` Jonathan Morton
2016-01-05 23:20 ` Steinar H. Gunderson
2016-01-05 23:17 ` Steinar H. Gunderson
2016-01-05 21:36 ` Benjamin Cronce
2016-01-06 0:01 ` Steinar H. Gunderson
2016-01-06 0:06 ` Stephen Hemminger
2016-01-06 0:22 ` Steinar H. Gunderson
2016-01-06 0:53 ` Stephen Hemminger
2016-01-06 0:55 ` Steinar H. Gunderson
2016-01-06 1:22 ` Stephen Hemminger
2016-01-06 6:18 ` Jonathan Morton
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