From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Christoph Lameter <clameter@engr.sgi.com>
Cc: Ravikiran G Thirumalai <kiran@scalex86.org>,
Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org,
"Shai Fultheim (Shai@scalex86.org)" <shai@scalex86.org>
Subject: Re: [patch] Cache align futex hash buckets
Date: Wed, 22 Feb 2006 11:40:08 +1100 [thread overview]
Message-ID: <43FBB2E8.2020300@yahoo.com.au> (raw)
In-Reply-To: <Pine.LNX.4.64.0602211030240.20166@schroedinger.engr.sgi.com>
Christoph Lameter wrote:
> On Tue, 21 Feb 2006, Nick Piggin wrote:
>
>
>>Ravikiran G Thirumalai wrote:
>>
>>>Following change places each element of the futex_queues hashtable on a
>>>different cacheline. Spinlocks of adjacent hash buckets lie on the same
>>>cacheline otherwise.
>>>
>>
>>It does not make sense to add swaths of unused memory into a hashtable for
>>this purpose, does it?
>
>
> It does if you essentially have a 4k cacheline (because you are doing NUMA
> in software with multiple PCs....) and transferring control of that
> cacheline is comparatively expensive.
>
Instead of 1MB hash with 256 entries in it covering 256 cachelines, you
have a 1MB hash with 65536(ish) entries covering 256 cachelines.
-
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2006-02-22 1:50 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-20 23:32 [patch] Cache align futex hash buckets Ravikiran G Thirumalai
2006-02-20 23:33 ` Andrew Morton
2006-02-20 23:34 ` Andrew Morton
2006-02-21 0:09 ` Ravikiran G Thirumalai
2006-02-21 0:23 ` Andrew Morton
2006-02-21 1:04 ` Ravikiran G Thirumalai
2006-02-21 1:09 ` Andrew Morton
2006-02-21 1:39 ` Ravikiran G Thirumalai
2006-02-21 14:44 ` Andi Kleen
2006-02-21 3:30 ` Nick Piggin
2006-02-21 18:33 ` Christoph Lameter
2006-02-21 23:14 ` Christoph Lameter
2006-02-22 0:40 ` Nick Piggin [this message]
2006-02-22 2:08 ` Andrew Morton
2006-02-22 2:35 ` Ravikiran G Thirumalai
2006-02-22 2:37 ` Nick Piggin
2006-02-22 20:17 ` Ravikiran G Thirumalai
2006-02-22 20:50 ` Andrew Morton
[not found] ` <20060223015144.GC3663@localhost.localdomain>
2006-02-23 2:08 ` Ravikiran G Thirumalai
2006-02-21 20:20 ` Ravikiran G Thirumalai
2006-02-22 0:45 ` Nick Piggin
2006-02-22 2:09 ` Andrew Morton
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