From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Daniel Phillips <phillips@google.com>
Cc: Mark Fasheh <mark.fasheh@oracle.com>, Andi Kleen <ak@suse.de>,
Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com
Subject: Re: [Ocfs2-devel] Ocfs2 performance bugs of doom
Date: Thu, 09 Mar 2006 18:43:10 +1100 [thread overview]
Message-ID: <440FDC8E.9060907@yahoo.com.au> (raw)
In-Reply-To: <440FCA81.7090608@google.com>
Daniel Phillips wrote:
> A poor distribution as you already noticed[1]. Even if it was a great
> distribution, we would still average a little over two nodes per bucket
> twice as many as we should allow unless you believe that people running
> cluster filesystems have too much time on their hands and need to waste
> some of it waiting for the computer to chew its way through millions
> of cold cache lines.
>
Just interested: do the locks have any sort of locality of lookup?
If so, then have you tried moving hot (ie. the one you've just found,
or newly inserted) hash entries to the head of the hash list?
In applications with really good locality you can sometimes get away
with small hash tables (10s even 100s of collisions on average) without
taking too big a hit this way, because your entries basically get sorted
LRU for you.
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2006-03-09 7:43 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-03 22:27 Ocfs2 performance bugs of doom Daniel Phillips
2006-03-04 0:53 ` Mark Fasheh
2006-03-04 3:42 ` Daniel Phillips
2006-03-04 7:36 ` Andrew Morton
2006-03-05 19:22 ` Mark Fasheh
2006-03-06 1:28 ` Daniel Phillips
2006-03-06 2:58 ` [Ocfs2-devel] " Mark Fasheh
2006-03-06 4:59 ` Daniel Phillips
2006-03-06 19:51 ` Mark Fasheh
2006-03-07 3:34 ` Andi Kleen
2006-03-07 4:58 ` Mark Fasheh
2006-03-07 6:56 ` [Ocfs2-devel] " Daniel Phillips
2006-03-09 6:26 ` Daniel Phillips
2006-03-09 7:26 ` Nick Piggin
2006-03-09 7:43 ` Nick Piggin [this message]
2006-03-09 4:19 ` Andi Kleen
2006-03-09 12:30 ` Nick Piggin
2006-03-10 5:14 ` Nick Piggin
2006-03-10 0:21 ` [Ocfs2-devel] Ocfs2 performance Mark Fasheh
2006-03-10 1:14 ` Bernd Eckenfels
2006-03-10 7:10 ` Joel Becker
2006-03-11 1:09 ` Mark Fasheh
2006-03-11 1:57 ` Bernd Eckenfels
2006-03-10 11:17 ` Daniel Phillips
2006-03-10 18:23 ` Zach Brown
2006-03-10 21:13 ` Daniel Phillips
2006-03-10 21:13 ` Daniel Phillips
2006-03-10 2:33 ` [Ocfs2-devel] Ocfs2 performance bugs of doom J. Bruce Fields
2006-03-10 10:27 ` Daniel Phillips
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