From: "Michael S. Tsirkin" <mst@redhat.com>
To: linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>,
Arnd Bergmann <arnd@arndb.de>, Davidlohr Bueso <dbueso@suse.de>,
Peter Zijlstra <peterz@infradead.org>,
Andrey Konovalov <andreyknvl@google.com>,
the arch/x86 maintainers <x86@kernel.org>,
virtualization <virtualization@lists.linux-foundation.org>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Borislav Petkov <bp@suse.de>, Andy Lutomirski <luto@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>
Subject: [PATCH v3 3/4] x86: tweak the comment about use of wmb for IO
Date: Wed, 13 Jan 2016 22:12:39 +0200 [thread overview]
Message-ID: <1452715911-12067-4-git-send-email-mst__37477.235045708$1452715990$gmane$org@redhat.com> (raw)
In-Reply-To: <1452715911-12067-1-git-send-email-mst@redhat.com>
On x86, we *do* still use the non-nop rmb/wmb for IO barriers, but even
that is generally questionable.
Leave them around as historial unless somebody can point to a case where
they care about the performance, but tweak the comment so people
don't think they are strictly required in all cases.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
arch/x86/include/asm/barrier.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
index a291745..bfb28ca 100644
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -6,7 +6,7 @@
/*
* Force strict CPU ordering.
- * And yes, this is required on UP too when we're talking
+ * And yes, this might be required on UP too when we're talking
* to devices.
*/
--
MST
next prev parent reply other threads:[~2016-01-13 20:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1452715911-12067-1-git-send-email-mst@redhat.com>
2016-01-13 20:12 ` [PATCH v3 1/4] x86: add cc clobber for addl Michael S. Tsirkin
2016-01-13 20:12 ` [PATCH v3 2/4] x86: drop a comment left over from X86_OOSTORE Michael S. Tsirkin
2016-01-13 20:12 ` Michael S. Tsirkin [this message]
2016-01-13 20:12 ` [PATCH v3 4/4] x86: drop mfence in favor of lock+addl Michael S. Tsirkin
2016-01-14 11:39 ` [PATCH v3 0/4] x86: faster mb()+documentation tweaks Borislav Petkov
2016-01-26 8:23 ` Michael S. Tsirkin
2016-01-26 8:26 ` Boris Petkov
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