From: Mike Galbraith <umgwanakikbuti@gmail.com>
To: Christoph Lameter <cl@linux.com>, Michal Hocko <mhocko@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable again and shut down on idle)
Date: Tue, 26 Jan 2016 19:31:18 +0100 [thread overview]
Message-ID: <1453833078.3534.59.camel@gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1601261022140.27957@east.gentwo.org>
On Tue, 2016-01-26 at 10:25 -0600, Christoph Lameter wrote:
> On Mon, 25 Jan 2016, Michal Hocko wrote:
>
> > > Why would the deferring cause this overhead?
> >
> > I guess the profile speaks for itself, doesn't it?
>
> But the system is going idle? Why would this impact performance?
We enter/exit idle a lot.
Your reluctance to move it seem to suggest that 99.99% of CPUs on the
planet chewing up cycles (measured) doing what for most is useless work
on every micro-idle is a perfectly fine price to pay to ensure that
.01% (or whatever tiny minority) get what they want.
I disagree. You're burning electrons for no benefit at all to me on my
box. You want to do high speed trading, that's fine, but I expect my
box to be able to pop in and out of idle without having to pay a toll
to the high speed trading bandits of the world, thank you very much.
This specialty thing does not belong in the generic fast path.
-Mike
next prev parent reply other threads:[~2016-01-26 18:32 UTC|newest]
Thread overview: 114+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-19 0:33 mm, vmstat: kernel BUG at mm/vmstat.c:1408! Sasha Levin
2015-12-19 0:33 ` Sasha Levin
2015-12-21 13:08 ` Christoph Lameter
2015-12-21 13:08 ` Christoph Lameter
2015-12-21 20:28 ` Sasha Levin
2015-12-21 20:28 ` Sasha Levin
2015-12-21 21:07 ` Sasha Levin
2015-12-21 21:07 ` Sasha Levin
2015-12-21 21:14 ` Christoph Lameter
2015-12-21 21:14 ` Christoph Lameter
2015-12-22 17:21 ` Christoph Lameter
2015-12-22 17:21 ` Christoph Lameter
2015-12-24 20:14 ` Sasha Levin
2015-12-29 17:01 ` Christoph Lameter
2015-12-29 17:01 ` Christoph Lameter
2015-12-29 17:18 ` Christoph Lameter
2015-12-29 17:18 ` Christoph Lameter
2016-01-04 18:05 ` Christoph Lameter
2016-01-04 18:05 ` Christoph Lameter
2016-01-04 18:46 ` Sasha Levin
2016-01-04 18:46 ` Sasha Levin
2016-01-12 11:31 ` Shiraz Hashim
2016-01-12 11:31 ` Shiraz Hashim
2016-01-12 12:23 ` Christoph Lameter
2016-01-12 12:23 ` Christoph Lameter
2016-01-12 12:27 ` Shiraz Hashim
2016-01-12 12:27 ` Shiraz Hashim
2016-01-13 11:36 ` Shiraz Hashim
2016-01-13 11:36 ` Shiraz Hashim
2016-01-13 12:32 ` Shiraz Hashim
2016-01-13 12:32 ` Shiraz Hashim
2016-01-14 21:06 ` Sasha Levin
2016-01-14 21:06 ` Sasha Levin
2016-01-20 14:37 ` Michal Hocko
2016-01-20 14:37 ` Michal Hocko
2016-01-20 14:56 ` Sasha Levin
2016-01-20 14:56 ` Sasha Levin
2016-01-20 15:10 ` Michal Hocko
2016-01-20 15:10 ` Michal Hocko
2016-01-20 15:20 ` Christoph Lameter
2016-01-20 15:20 ` Christoph Lameter
2016-01-20 15:49 ` Sasha Levin
2016-01-20 15:49 ` Sasha Levin
2016-01-20 15:55 ` Christoph Lameter
2016-01-20 15:55 ` Christoph Lameter
2016-01-20 21:28 ` Michal Hocko
2016-01-20 21:28 ` Michal Hocko
2016-01-20 21:57 ` Christoph Lameter
2016-01-20 21:57 ` Christoph Lameter
2016-01-21 8:24 ` Michal Hocko
2016-01-21 8:24 ` Michal Hocko
2016-01-21 15:45 ` Christoph Lameter
2016-01-21 15:45 ` Christoph Lameter
2016-01-21 16:51 ` Michal Hocko
2016-01-21 16:51 ` Michal Hocko
2016-01-21 17:38 ` Christoph Lameter
2016-01-21 17:38 ` Christoph Lameter
2016-01-22 11:00 ` Shiraz Hashim
2016-01-22 11:00 ` Shiraz Hashim
2016-01-22 14:04 ` Michal Hocko
2016-01-22 14:04 ` Michal Hocko
2016-01-22 16:07 ` Christoph Lameter
2016-01-22 16:07 ` Christoph Lameter
2016-01-22 16:12 ` Michal Hocko
2016-01-22 16:12 ` Michal Hocko
2016-01-22 16:46 ` Christoph Lameter
2016-01-22 16:46 ` Christoph Lameter
2016-01-22 17:12 ` Michal Hocko
2016-01-22 17:12 ` Michal Hocko
2016-01-23 16:21 ` fast path cycle muncher (vmstat: make vmstat_updater deferrable again and shut down on idle) Mike Galbraith
2016-01-24 0:33 ` Christoph Lameter
2016-01-24 2:46 ` Mike Galbraith
2016-01-24 3:46 ` Christoph Lameter
2016-01-24 5:36 ` Mike Galbraith
2016-01-25 17:42 ` Michal Hocko
2016-01-25 18:02 ` Christoph Lameter
2016-01-25 20:13 ` Michal Hocko
2016-01-26 16:25 ` Christoph Lameter
2016-01-26 18:31 ` Mike Galbraith [this message]
2016-01-26 18:34 ` Christoph Lameter
2016-01-26 18:45 ` Mike Galbraith
2016-01-26 19:20 ` Christoph Lameter
2016-01-27 3:12 ` Mike Galbraith
2016-01-27 4:15 ` Mike Galbraith
2016-01-27 16:28 ` Christoph Lameter
2016-01-28 15:36 ` Frederic Weisbecker
2016-01-28 16:42 ` Christoph Lameter
2016-01-26 2:14 ` Mike Galbraith
2016-01-26 2:25 ` Mike Galbraith
2016-01-26 16:26 ` Christoph Lameter
2016-01-26 17:39 ` Mike Galbraith
2016-01-26 18:19 ` Christoph Lameter
2016-01-26 16:26 ` Christoph Lameter
2016-01-26 17:08 ` Mike Galbraith
2016-01-26 18:22 ` Christoph Lameter
2016-01-26 19:09 ` Mike Galbraith
2016-01-26 19:22 ` Christoph Lameter
2016-01-27 16:48 ` [PATCH] mm, vmstat: make quiet_vmstat lighter (was: Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable) " Michal Hocko
2016-01-27 17:03 ` Mike Galbraith
2016-01-27 18:26 ` Christoph Lameter
2016-01-28 15:21 ` Michal Hocko
2016-01-28 16:40 ` Christoph Lameter
2016-01-28 16:53 ` Michal Hocko
2016-01-28 17:05 ` Christoph Lameter
2016-01-28 15:31 ` Michal Hocko
2016-01-28 15:37 ` [PATCH] vmstat: make vmstat_update deferrable (was: Re: [PATCH] mm, vmstat: make quiet_vmstat lighter) " Michal Hocko
2016-01-28 16:48 ` Christoph Lameter
2016-01-28 16:42 ` [PATCH] mm, vmstat: make quiet_vmstat lighter (was: Re: fast " Christoph Lameter
2016-01-24 16:57 ` mm, vmstat: kernel BUG at mm/vmstat.c:1408! Linus Torvalds
2016-01-24 16:57 ` Linus Torvalds
2016-01-20 15:14 ` Christoph Lameter
2016-01-20 15:14 ` Christoph Lameter
2016-01-20 15:20 ` Michal Hocko
2016-01-20 15:20 ` Michal Hocko
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