From: Christoph Lameter <cl@linux.com>
To: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Joonsoo Kim <js1304@gmail.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Linux Memory Management List <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linux-Netdev <netdev@vger.kernel.org>,
Alexander Duyck <alexander.duyck@gmail.com>
Subject: Re: [PATCH 7/7] slub: initial bulk free implementation
Date: Tue, 16 Jun 2015 11:04:45 -0500 (CDT) [thread overview]
Message-ID: <alpine.DEB.2.11.1506161104060.5683@east.gentwo.org> (raw)
In-Reply-To: <20150616175231.427499ae@redhat.com>
On Tue, 16 Jun 2015, Jesper Dangaard Brouer wrote:
> It is very important that everybody realizes that the save+restore
> variant is very expensive, this is key:
>
> CPU: i7-4790K CPU @ 4.00GHz
> * local_irq_{disable,enable}: 7 cycles(tsc) - 1.821 ns
> * local_irq_{save,restore} : 37 cycles(tsc) - 9.443 ns
>
> Even if EVERY object need to call slowpath/__slab_free() it will be
> faster than calling the fallback. Because I've demonstrated the call
> this_cpu_cmpxchg_double() costs 9 cycles.
But the cmpxchg also stores a value. You need to add the cost of the store
to the cycles.
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prev parent reply other threads:[~2015-06-16 16:04 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-15 15:51 [PATCH 0/7] slub: bulk alloc and free for slub allocator Jesper Dangaard Brouer
2015-06-15 15:51 ` [PATCH 1/7] slab: infrastructure for bulk object allocation and freeing Jesper Dangaard Brouer
2015-06-15 16:45 ` Alexander Duyck
2015-06-15 16:50 ` Christoph Lameter
2015-06-16 21:44 ` Andrew Morton
2015-06-15 15:52 ` [PATCH 2/7] slub bulk alloc: extract objects from the per cpu slab Jesper Dangaard Brouer
2015-06-16 7:21 ` Joonsoo Kim
2015-06-16 15:05 ` Christoph Lameter
2015-06-16 21:48 ` Andrew Morton
2015-06-17 6:24 ` Jesper Dangaard Brouer
2015-06-15 15:52 ` [PATCH 3/7] slub: reduce indention level in kmem_cache_alloc_bulk() Jesper Dangaard Brouer
2015-06-15 15:52 ` [PATCH 4/7] slub: fix error path bug in kmem_cache_alloc_bulk Jesper Dangaard Brouer
2015-06-16 21:51 ` Andrew Morton
2015-06-17 6:25 ` Jesper Dangaard Brouer
2015-06-15 15:52 ` [PATCH 5/7] slub: kmem_cache_alloc_bulk() move clearing outside IRQ disabled section Jesper Dangaard Brouer
2015-06-15 15:52 ` [PATCH 6/7] slub: improve bulk alloc strategy Jesper Dangaard Brouer
2015-06-15 16:36 ` Christoph Lameter
2015-06-16 21:53 ` Andrew Morton
2015-06-17 6:29 ` Jesper Dangaard Brouer
2015-06-15 15:52 ` [PATCH 7/7] slub: initial bulk free implementation Jesper Dangaard Brouer
2015-06-15 16:34 ` Christoph Lameter
2015-06-16 8:04 ` Jesper Dangaard Brouer
2015-06-15 17:04 ` Alexander Duyck
2015-06-16 7:23 ` Joonsoo Kim
2015-06-16 9:20 ` Jesper Dangaard Brouer
2015-06-16 12:00 ` Joonsoo Kim
2015-06-16 13:58 ` Jesper Dangaard Brouer
2015-06-16 15:06 ` Christoph Lameter
2015-06-16 7:28 ` Joonsoo Kim
2015-06-16 8:21 ` Jesper Dangaard Brouer
2015-06-16 8:57 ` Jesper Dangaard Brouer
2015-06-16 12:05 ` Joonsoo Kim
2015-06-16 15:10 ` Christoph Lameter
2015-06-16 15:52 ` Jesper Dangaard Brouer
2015-06-16 16:04 ` Christoph Lameter [this message]
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