From: Mike Galbraith <efault@gmx.de>
To: Steven Sistare <steven.sistare@oracle.com>,
Rohit Jain <rohit.k.jain@oracle.com>,
linux-kernel@vger.kernel.org
Cc: peterz@infradead.org, mingo@redhat.com, joelaf@google.com,
jbacik@fb.com, riel@redhat.com, juri.lelli@redhat.com,
dhaval.giani@oracle.com
Subject: Re: [RFC 2/2] Introduce sysctl(s) for the migration costs
Date: Fri, 09 Feb 2018 18:50:09 +0100 [thread overview]
Message-ID: <1518198609.26824.43.camel@gmx.de> (raw)
In-Reply-To: <88efe20e-75a9-6805-3ae4-dc67742f9057@oracle.com>
On Fri, 2018-02-09 at 12:33 -0500, Steven Sistare wrote:
> On 2/9/2018 12:08 PM, Mike Galbraith wrote:
>
> > Shrug. It's bogus no mater what we do. Once Upon A Time, a cost
> > number was generated via measurement, but the end result was just as
> > bogus as a number pulled out of the ether. How much bandwidth you have
> > when blasting data to/from wherever says nothing about misses you avoid
> > vs those you generate.
>
> Yes, yes and yes. I cannot make the original tunable less bogus. Using a smaller
> cost for closer caches still makes logical sense and is supported by the data.
You forgot to write "microscopic" before "data" :) I'm mostly agnostic
about this, but don't like the yet more knobs that 99.99% won't touch.
-Mike
next prev parent reply other threads:[~2018-02-09 17:50 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-08 22:19 [RFC 0/2] sched: Make idle_balance smarter about topology Rohit Jain
2018-02-08 22:19 ` [RFC 1/2] sched: reduce migration cost between faster caches for idle_balance Rohit Jain
2018-02-09 3:42 ` Mike Galbraith
2018-02-09 16:08 ` Steven Sistare
2018-02-10 6:37 ` Mike Galbraith
2018-02-15 16:35 ` Steven Sistare
2018-02-15 18:07 ` Mike Galbraith
2018-02-15 18:21 ` Steven Sistare
2018-02-15 18:39 ` Mike Galbraith
2018-02-15 18:07 ` Rohit Jain
2018-02-16 4:53 ` Mike Galbraith
2018-02-08 22:19 ` [RFC 2/2] Introduce sysctl(s) for the migration costs Rohit Jain
2018-02-09 3:54 ` Mike Galbraith
2018-02-09 16:10 ` Steven Sistare
2018-02-09 17:08 ` Mike Galbraith
2018-02-09 17:33 ` Steven Sistare
2018-02-09 17:50 ` Mike Galbraith [this message]
2018-02-12 15:28 ` Peter Zijlstra
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