From: "H. Peter Anvin" <hpa@zytor.com>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
Ulrich Drepper <drepper@redhat.com>,
Davide Libenzi <davidel@xmailserver.org>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andi Kleen <ak@suse.de>
Subject: Re: getting processor numbers
Date: Tue, 03 Apr 2007 22:16:37 -0700 [thread overview]
Message-ID: <461334B5.7070607@zytor.com> (raw)
In-Reply-To: <4613330C.1020701@cosmosbay.com>
Eric Dumazet wrote:
>
> There is one thing that always worried me.
>
> Intel & AMD manuals make clear that mixing data and program in the same
> page is bad for performance.
>
> In particular, x86_64 vsyscall put jiffies and other
> vsyscall_gtod_data_t right in the midle of code. That is certainly not
> wise.
>
> A probably sane implementation should use two pages, one for code, one
> for data.
>
Mutable data should be separated from code. I think any current CPU
will do fine as long as they are in separate 128-byte chunks, but they
need at least that much separation.
Readonly data does not need to be separated from code.
-hpa
next prev parent reply other threads:[~2007-04-04 5:18 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-03 16:54 getting processor numbers Ulrich Drepper
2007-04-03 17:30 ` linux-os (Dick Johnson)
2007-04-03 17:37 ` Ulrich Drepper
2007-04-03 17:56 ` Dr. David Alan Gilbert
2007-04-03 18:11 ` Andi Kleen
2007-04-03 17:17 ` Ulrich Drepper
2007-04-03 17:22 ` Alan Cox
2007-04-03 17:30 ` Andi Kleen
2007-04-03 20:24 ` Jeremy Fitzhardinge
2007-04-03 17:27 ` Andi Kleen
2007-04-03 17:30 ` Ulrich Drepper
2007-04-03 17:35 ` Andi Kleen
2007-04-03 17:45 ` Ulrich Drepper
2007-04-03 17:58 ` Andi Kleen
2007-04-03 18:05 ` Ulrich Drepper
2007-04-03 18:11 ` Andi Kleen
2007-04-03 18:21 ` Ulrich Drepper
2007-04-03 17:44 ` Siddha, Suresh B
2007-04-03 17:59 ` Ulrich Drepper
2007-04-03 19:40 ` Jakub Jelinek
2007-04-03 20:13 ` Ingo Oeser
2007-04-03 23:38 ` J.A. Magallón
2007-04-03 19:55 ` Ulrich Drepper
2007-04-03 20:13 ` Siddha, Suresh B
2007-04-03 20:19 ` Ulrich Drepper
2007-04-03 20:32 ` Eric Dumazet
2007-04-03 20:20 ` Nathan Lynch
2007-04-03 19:15 ` Davide Libenzi
2007-04-03 19:32 ` Ulrich Drepper
2007-04-04 0:31 ` H. Peter Anvin
2007-04-04 0:35 ` Jeremy Fitzhardinge
2007-04-04 0:38 ` H. Peter Anvin
2007-04-04 5:09 ` Eric Dumazet
2007-04-04 5:16 ` H. Peter Anvin [this message]
2007-04-04 5:22 ` Jeremy Fitzhardinge
2007-04-04 5:40 ` H. Peter Anvin
2007-04-04 5:46 ` Eric Dumazet
2007-04-04 5:29 ` Eric Dumazet
2007-04-03 20:16 ` Andrew Morton
[not found] ` <4612BB89.8040102@redhat.com>
[not found] ` <20070403141348.9bcdb13e.akpm@linux-foundation.org>
2007-04-03 22:13 ` Ulrich Drepper
2007-04-03 22:48 ` Andrew Morton
2007-04-03 23:00 ` Ulrich Drepper
2007-04-03 23:23 ` Andrew Morton
2007-04-03 23:54 ` Ulrich Drepper
2007-04-04 2:55 ` Paul Jackson
2007-04-04 8:39 ` Oleg Nesterov
2007-04-04 9:39 ` Ingo Molnar
2007-04-04 8:57 ` Oleg Nesterov
2007-04-04 10:01 ` Ingo Molnar
2007-04-04 2:58 ` Paul Jackson
2007-04-04 3:04 ` Paul Jackson
2007-04-04 2:52 ` Paul Jackson
2007-04-04 2:04 ` Paul Jackson
2007-04-04 6:47 ` Jakub Jelinek
2007-04-04 7:02 ` Paul Jackson
2007-04-04 14:51 ` Cliff Wickman
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