From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
To: linux-ia64@vger.kernel.org
Subject: RE: [RFC] 4-level page table directories.
Date: Tue, 08 Nov 2005 20:07:02 +0000 [thread overview]
Message-ID: <200511082007.jA8K72g18882@unix-os.sc.intel.com> (raw)
In-Reply-To: <20051027041709.GA13193@attica.americas.sgi.com>
Magenheimer, Dan wrote on Tuesday, November 08, 2005 10:53 AM
> The cost is of course a global (or cpu) variable access for
> every pud/pgd/pmd/pte macro usage, but one would expect the
> global would always be in cache/TLB so the performance impact
> should be near zero.
That is only true when your entire working set fits into the
cache (both kernel and user data). Here you burn an extra cache
line for global page size variable, it will displace one cache
line for user application. Enterprise workloads all have working
set much bigger than CPU's last level cache. In the end, both
kernel and user side hurt with more cache miss rate.
- Ken
next prev parent reply other threads:[~2005-11-08 20:07 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-27 4:17 [RFC] 4-level page table directories Robin Holt
2005-10-28 5:19 ` Ian Wienand
2005-10-28 11:19 ` Robin Holt
2005-10-28 23:23 ` Luck, Tony
2005-10-28 23:55 ` Chen, Kenneth W
2005-10-29 0:49 ` Grant Grundler
2005-10-29 2:18 ` David Mosberger-Tang
2005-11-01 12:13 ` Robin Holt
2005-11-01 15:41 ` David Mosberger-Tang
2005-11-02 10:35 ` Robin Holt
2005-11-02 13:26 ` Robin Holt
2005-11-02 16:11 ` Luck, Tony
2005-11-02 16:23 ` Robin Holt
2005-11-02 16:30 ` Luck, Tony
2005-11-02 17:16 ` Robin Holt
2005-11-02 18:59 ` David Mosberger-Tang
2005-11-02 22:26 ` Ian Wienand
2005-11-03 1:36 ` Gerald Pfeifer
2005-11-03 1:53 ` Chen, Kenneth W
2005-11-03 3:55 ` Jack Steiner
2005-11-03 16:36 ` Robin Holt
2005-11-03 19:59 ` Chen, Kenneth W
2005-11-04 17:58 ` Luck, Tony
2005-11-04 21:37 ` Robin Holt
2005-11-04 21:42 ` Chen, Kenneth W
2005-11-04 22:50 ` Chen, Kenneth W
2005-11-07 21:18 ` Luck, Tony
2005-11-08 0:22 ` Rohit Seth
2005-11-08 12:43 ` Robin Holt
2005-11-08 18:23 ` Boehm, Hans
2005-11-08 18:52 ` Magenheimer, Dan (HP Labs Fort Collins)
2005-11-08 18:56 ` Rohit Seth
2005-11-08 19:36 ` Robin Holt
2005-11-08 20:07 ` Chen, Kenneth W [this message]
2005-11-08 20:27 ` Chen, Kenneth W
2005-11-08 22:09 ` Ian Wienand
2005-11-08 23:58 ` Gerald Pfeifer
2005-11-09 0:08 ` David Mosberger-Tang
2005-11-09 0:22 ` Rohit Seth
2005-11-09 0:46 ` Magenheimer, Dan (HP Labs Fort Collins)
2005-11-09 1:18 ` Chen, Kenneth W
2005-11-09 12:11 ` Robin Holt
2005-11-09 14:29 ` Robin Holt
2005-11-09 18:22 ` Chen, Kenneth W
2005-11-09 18:39 ` Luck, Tony
2005-11-10 0:03 ` Gerald Pfeifer
2005-11-10 0:23 ` Jack Steiner
2005-11-10 0:27 ` Luck, Tony
2005-11-10 2:54 ` Jack Steiner
2005-11-10 9:13 ` Robin Holt
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