linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Thomas Gleixner <tglx@linutronix.de>
To: Davidlohr Bueso <dave@stgolabs.net>
Cc: LKML <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org, Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Michal Hocko <mhocko@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [patch V2 2/2] mm/memory-hotplug: Switch locking to a percpu rwsem
Date: Tue, 4 Jul 2017 17:32:37 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.20.1707041732030.9000@nanos> (raw)
In-Reply-To: <20170704152206.GB11168@linux-80c1.suse>

On Tue, 4 Jul 2017, Davidlohr Bueso wrote:
> On Tue, 04 Jul 2017, Davidlohr Bueso wrote:
> 
> > As a side effect you end up optimizing get/put_online_mems() at the cost
> > of more overhead for the actual hotplug operation, which is rare and of less
> > performance importance.
> 
> So nm this, the reader side actually gets _more_ expensive with pcpu-rwsems
> due to at least two full barriers for each get/put operation.

Compared to a mutex_lock/unlock() pair on a global mutex ....

  reply	other threads:[~2017-07-04 15:32 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-04  9:32 [patch V2 0/2] mm/memory_hotplug: Cure potential deadlocks vs. cpu hotplug lock Thomas Gleixner
2017-07-04  9:32 ` [patch V2 1/2] mm: swap: Provide lru_add_drain_all_cpuslocked() Thomas Gleixner
2017-07-04 10:58   ` Michal Hocko
2017-07-04 12:48     ` Thomas Gleixner
2017-07-04 12:52       ` Michal Hocko
2017-07-04 12:07   ` Vlastimil Babka
2017-07-04 12:35     ` Thomas Gleixner
2017-07-04  9:32 ` [patch V2 2/2] mm/memory-hotplug: Switch locking to a percpu rwsem Thomas Gleixner
2017-07-04 10:59   ` Michal Hocko
2017-07-04 12:10   ` Vlastimil Babka
2017-07-04 12:49     ` Thomas Gleixner
2017-07-04 15:01   ` Davidlohr Bueso
2017-07-04 15:22     ` Davidlohr Bueso
2017-07-04 15:32       ` Thomas Gleixner [this message]
2017-07-04 15:42         ` Davidlohr Bueso
2017-07-05 21:53 ` [patch V2 0/2] mm/memory_hotplug: Cure potential deadlocks vs. cpu hotplug lock Andrew Morton
2017-07-06  6:34   ` Thomas Gleixner

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=alpine.DEB.2.20.1707041732030.9000@nanos \
    --to=tglx@linutronix.de \
    --cc=akpm@linux-foundation.org \
    --cc=aryabinin@virtuozzo.com \
    --cc=dave@stgolabs.net \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@kernel.org \
    --cc=peterz@infradead.org \
    --cc=vbabka@suse.cz \
    --cc=vdavydov.dev@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).