From: Steven Rostedt <rostedt@goodmis.org>
To: Christoph Lameter <cl@linux.com>
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 22:51:30 -0500 [thread overview]
Message-ID: <20150115225130.00c0c99a@grimm.local.home> (raw)
In-Reply-To: <alpine.DEB.2.11.1501152126300.13976@gentwo.org>
On Thu, 15 Jan 2015 21:27:14 -0600 (CST)
Christoph Lameter <cl@linux.com> wrote:
>
> 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.
Have you disassembled your code?
Looking at put_cpu_partial() from 3.19-rc3 where it does:
oldpage = this_cpu_read(s->cpu_slab->partial);
I get:
mov %gs:0x18(%rax),%rdx
Looks to me that %gs is used.
I haven't done benchmarks in a while, so perhaps accessing the %gs
segment isn't as expensive as I saw it before. I'll have to profile
function tracing on my i7 and see where things are slow again.
-- Steve
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next prev parent reply other threads:[~2015-01-16 3:51 UTC|newest]
Thread overview: 17+ 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 4:20 ` 答复: " Zhang, Yanfei
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
2015-01-16 3:51 ` Steven Rostedt [this message]
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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