From: Andre Przywara <andre.przywara@amd.com>
To: <hpa@zytor.com>, <tglx@linutronix.de>, <mingo@elte.hu>
Cc: <linux-kernel@vger.kernel.org>, <andreas.herrmann3@amd.com>,
Andre Przywara <andre.przywara@amd.com>
Subject: [PATCH] x86/amd: disable way access filter on affected CPUs
Date: Wed, 24 Oct 2012 09:56:17 +0200 [thread overview]
Message-ID: <1351065377-1989-1-git-send-email-andre.przywara@amd.com> (raw)
The WAF may hurt the performance of some workloads, caused by
aliasing issues in the L1 cache.
Disable it on the affected CPUs.
Signed-off-by: Andre Przywara <andre.przywara@amd.com>
---
arch/x86/kernel/cpu/amd.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index f7e98a2..1b7d165 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -631,6 +631,20 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
}
}
+ /*
+ * The way access filter has a performance penalty on some workloads.
+ * Disable it on the affected CPUs.
+ */
+ if ((c->x86 == 0x15) &&
+ (c->x86_model >= 0x02) && (c->x86_model < 0x20)) {
+ u64 val;
+
+ if (!rdmsrl_safe(0xc0011021, &val) && !(val & 0x1E)) {
+ val |= 0x1E;
+ wrmsrl_safe(0xc0011021, val);
+ }
+ }
+
cpu_detect_cache_sizes(c);
/* Multi core CPU? */
--
1.7.12.1
next reply other threads:[~2012-10-24 7:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-24 7:56 Andre Przywara [this message]
2012-10-24 10:46 ` [PATCH] x86/amd: disable way access filter on affected CPUs Ingo Molnar
2012-10-24 15:35 ` Andre Przywara
2012-10-26 14:56 ` Ingo Molnar
2012-10-31 16:20 ` Andre Przywara
2012-11-01 21:33 ` [tip:x86/urgent] x86, amd: Disable way access filter on Piledriver CPUs tip-bot for Andre Przywara
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=1351065377-1989-1-git-send-email-andre.przywara@amd.com \
--to=andre.przywara@amd.com \
--cc=andreas.herrmann3@amd.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=tglx@linutronix.de \
/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).