From: Christoph Lameter <cl@linux.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Jesper Dangaard Brouer <brouer@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v2 1/2] mm/slub: optimize alloc/free fastpath by removing preemption on/off
Date: Thu, 15 Jan 2015 21:27:14 -0600 (CST) [thread overview]
Message-ID: <alpine.DEB.2.11.1501152126300.13976@gentwo.org> (raw)
In-Reply-To: <20150115203045.00e9fb73@grimm.local.home>
On Thu, 15 Jan 2015, Steven Rostedt wrote:
> profiling function tracing I discovered that accessing preempt_count
> was actually quite expensive, even just to read. But it may not be as
> bad since Peter Zijlstra converted preempt_count to a per_cpu variable.
> Although, IIRC, the perf profiling showed the access to the %gs
> register was where the time consuming was happening, which is what
> I believe per_cpu variables still use.
The %gs register is not used since the address of the per cpu area is
available as one of the first fields in the per cpu areas.
next prev parent reply other threads:[~2015-01-16 3:27 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-15 7:40 Joonsoo Kim
2015-01-15 7:40 ` [PATCH v2 2/2] mm: don't use compound_head() in virt_to_head_page() Joonsoo Kim
2015-01-16 1:16 ` Andrew Morton
2015-01-16 3:30 ` Christoph Lameter
2015-01-19 6:16 ` Joonsoo Kim
2015-01-15 8:10 ` [PATCH v2 1/2] mm/slub: optimize alloc/free fastpath by removing preemption on/off Jesper Dangaard Brouer
2015-01-16 1:16 ` Andrew Morton
2015-01-16 1:30 ` Steven Rostedt
2015-01-16 3:27 ` Christoph Lameter [this message]
2015-01-16 3:51 ` Steven Rostedt
2015-01-16 3:57 ` Christoph Lameter
2015-01-16 4:07 ` Steven Rostedt
2015-01-16 13:40 ` Eric Dumazet
2015-01-16 16:37 ` Steven Rostedt
2015-01-16 4:04 ` Steven Rostedt
2015-01-16 3:28 ` Christoph Lameter
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