From: Andi Kleen <ak@muc.de>
To: torvalds@transmeta.com
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] Support worst case cache line sizes as config option
Date: Sun, 27 Apr 2003 04:23:46 +0200 [thread overview]
Message-ID: <20030427022346.GA27933@averell> (raw)
This mirrors a change that has been in the SuSE/aa 2.4 kernel for a long time.
For a generic binary kernel you really want to assume the worst case
cache line size. That's the P4's 128 byte currently.
The overhead of having the cache line size bigger on other CPUs is not
that bad, but if it is too small it will cost you dearly on SMP and
even a bit on UP in device drivers.
This patch adds a new CONFIG_X86_GENERIC option for this. It currently
only forces 128byte cache lines, but could be used for more in the future.
diff -u linux-gencpu/arch/i386/Kconfig-o linux-gencpu/arch/i386/Kconfig
--- linux-gencpu/arch/i386/Kconfig-o 2003-04-27 02:40:32.000000000 +0200
+++ linux-gencpu/arch/i386/Kconfig 2003-04-27 03:50:08.000000000 +0200
@@ -273,6 +273,13 @@
endchoice
+config X86_GENERIC
+ bool "Generic x86 support"
+ help
+ Include some tuning for non selected x86 CPUs too.
+ when it has moderate overhead. This is intended for generic
+ distributions kernels.
+
#
# Define implied options from the CPU selection here
#
@@ -288,10 +295,10 @@
config X86_L1_CACHE_SHIFT
int
+ default "7" if MPENTIUM4 || X86_GENERIC
default "4" if MELAN || M486 || M386
default "5" if MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCRUSOE || MCYRIXIII || MK6 || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || M586 || MVIAC3_2
default "6" if MK7 || MK8
- default "7" if MPENTIUM4
config RWSEM_GENERIC_SPINLOCK
bool
next reply other threads:[~2003-04-27 2:11 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-04-27 2:23 Andi Kleen [this message]
[not found] ` <BKEGKPICNAKILKJKMHCAAEPNCIAA.Riley@Williams.Name>
2003-04-27 12:52 ` [PATCH] Support worst case cache line sizes as config option Andi Kleen
2003-04-28 9:16 ` Adrian Bunk
2003-04-28 11:47 ` Andi Kleen
2003-04-28 12:19 ` Adrian Bunk
2003-04-28 12:48 ` Jamie Lokier
2003-04-28 22:00 ` Andi Kleen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20030427022346.GA27933@averell \
--to=ak@muc.de \
--cc=linux-kernel@vger.kernel.org \
--cc=torvalds@transmeta.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).